David Harley's Alt.Comp.Virus FAQ

alt.comp.virus (Frequently Asked Questions) ******************************************* Version 1.01e: Part 1 of 4 Last-modified 16th April 1996 ("`-''-/").___..--''"`-._ `6_ 6 ) `-. ( ).`-.__.`) (_Y_.)' ._ ) `._ `. ``-..-' _..`--'_..-_/ /--'_.' ,' (il),-'' (li),' ((!.-' ADMINISTRIVIA Disclaimer This document is primarily concerned with defending the integrity of computing systems and preventing damage caused by viruses or other malicious and/or other unauthorized software. It attempts to address many of the issues which are frequently discussed on alt.comp.virus, but does not claim to represent all shades of opinion among the users of a.c.v. - in particular, it does not include information which, in my estimation, is likely to be of more help to those interested in the spreading of unauthorized and/or malicious software than to those who wish to be protected from it. This document is an honest attempt to help individuals with computer virus-related problems and queries. It can *not* be regarded as being in any sense authoritative, and has no legal standing. The authors accept no responsibility for errors or omissions, or for any ill effects resulting from the use of any information contained in this document. Not all the views expressed in this document are mine, and those views which *are* mine are not necessarily shared by my employer. David Harley Copyright Notice Copyright on all contributions to this FAQ remains with the authors and all rights are reserved. It may, however, be freely distributed and quoted - accurately, and with due credit. It may not be reproduced for profit or distributed in part or as a whole with any product for which a charge is made, except with the prior permission of the copyright holders. To obtain such permission, please contact the maintainer of the FAQ. Availability The latest version of this document is available from: (1) ftp://ftp.icnet.uk/icrf-public/acv.FAQ (2) harley@icrf.icnet.uk Subject: request a.c.v. FAQ Message: Optional, but unlikely to be read! This request format will get you the FAQ in four parts. It will shortly also be available archived for Mac or PC, mailed in MIME format or uuencoded. (Watch this space) A number of individuals and sites have agreed to make it available via anonymous FTP and/or WWW. There'll be an update on this in due course, but these include: FTP://ftp.gate.net/pub/users/ris1/acvfaq.zip http://www.drsolomon.com/ http://www.innet.net/~ewillems/ http://www.agora.stm.it/N.Ferri/infos.htm It is also available on AOL: America Online: (Virus Information Center: Keyword VIRUS ---------------------------------------------------------------------- PREFACE (i) What is the FAQ, and who is it for? ----------------------------------- This FAQ is intended to make available answers to questions which are repeatedly asked on alt.comp.virus, and tries to gather the most useful information regarding this group and the issues discussed here into a relatively short document. The hope is to produce (eventually) an easily-digested document for newcomers, as a means of saving those who regularly reply to posted questions having to re-invent the wheel each time. I recommend that you read this FAQ in conjunction with the comp.virus (VIRUS-L)FAQ, which gives more detailed information regarding some issues which are, inevitably, covered in both FAQs. The VIRUS-L/comp.virus FAQ is regularly posted to the comp.virus newsgroup. The latest version should be available as: ftp://cert.org/pub/virus-l/FAQ.virus-l You can get the Mk. 2 version at ftp://ftp.datafellows.com/pub/misc/anti-vir/vlfaq200.zip ftp://cs.ucr.edu/pub/virus-l/ which is very long and very thorough. This document is subject to revision, so the file name may change. (ii) Credits/Acknowledgements ------------------------ The following have contributed text and/or ideas and/or proofreading/corrections and/or URLs to the a.c.v. FAQ. Vesselin Bontchev Bruce Burrell Graham Cluley Henri Delger Edward Fenton Nicola Ferri David Harley R. Wallace Hale Norman Hirsch Matthew Holtz Mikko H. Hypponen Douglas A. Kaufman Susan Lesch Mike Ramey Perry Rovers Megan Skinner Fridrik Skulason Alan Solomon Ken Stieers Hector Ugalde George Wenzel Caroline Wilson Acknowledgement is also due to the work of Ken Van Wyk, former moderator of VIRUS-L/comp.virus, and the contributors to the comp.virus FAQ (both versions). Thanks also to ked@intac.com, who mailed me a copy of the FAQ he posted to a.c.v. some months before this one was begun, David J. Loundy for assistance regarding legal issues, and to Nick FitzGerald, the moderator of comp.virus and maintainer of the Mk. II comp.virus FAQ. And especially to George Wenzel and Lucky the Cat. (iii) Guide to posting etiquette -------------------------- Messages asking for help posted to alt.comp.virus are more likely to receive a useful response if they conform to accepted standards of civility. The newsgroup news.announce.newusers includes information on good newsgroup etiquette, or try ftp://rtfm.mit.edu/pub/usenet/news.answers http://www.fau.edu/rinaldi/netiquette.html However, adhering to the following guidelines would be particularly helpful: * Keep your lines short (say 72 characters per line), so that anyone who follows up doesn't have to reformat quoted text to keep it readable). * Don't quote all or most of a message you're following up unless it's either very short, or necessary in order to address each point made. In the latter case, please put the point you're answering close to your answer and try to format it so that it's readable. Remember that some people have to pay for connection/download time. * On the other hand, a message which says something like 'I totally agree' without including enough of the original for us to tell what you're agreeing with is a waste of bandwidth. * Keep it polite. It's unlikely that anyone who replies to your posting is being paid to do so, and it wouldn't excuse bad manners if they were. Of course, the cut and thrust of debate may be a different matter altogether.... * Asking for a reply by direct e-mail may be reasonable if you need an urgent solution or are using a borrowed account. It isn't reasonable if you simply can't be bothered to check newsgroups. At least try to think up a good excuse, and be prepared to offer a summary to the group. * Check that there isn't already a thread on the subject you're asking about before posting yet another 'Has anyone heard of the GOOD TIMES virus?' message. If there is, check it first: the answer to your question may already be there (if it isn't in this document!). Please remember that many people have to pay for connect time, and don't appreciate duplicate postings or uuencoded binaries. * If you want to follow up a message which doesn't seem particularly relevant to alt.comp.virus, check the 'Newsgroups:' header: there have been a lot of responses to spammings recently which have made increased the bandwidth used, often quite unnecessarily. * Please don't post test messages here unless you really need to: use one of the newsgroups intended for the purpose: there is probably one local to your news server - ask your Systems Administrator, provider or local helpdesk. If you must post to the entire Internet, use misc.test - if you do, put the word IGNORE in your Subject: field, or you'll get auto-responder messages in your mail for weeks afterwards. Look through the postings in news.announce.newusers for relevant guidelines before you post. * If you get into an exchange of E-mail, please remember that not everyone can handle all forms of E-mail attachment (uuencoded, MIME format etc. - if it's text, *send* it as text. NB also that (uu)encoding text makes it longer as well as unreadable, so don't! (iv) How to ask on the alt.comp.virus newsgroup for help --------------------------------------------------- The more relevant information you give us, the more we can help you. It helps to tell us the following: * What you think the problem is (you might think it's a virus, but maybe it isn't) * What the symptoms are. If you ran some software that gave you a message, tell us which package, version number, and the exact wording of the message. * Please be as accurate as possible about the order in which events happened. * If just one file is infected, give the filename. * If you're running more than one anti-virus product, please list them (including version number), and say what each one said about the possible virus. * Which version of which operating system you are running. * Any other configuration information which you think may have a bearing. Don't take action, then ask if that was the right action - if it wasn't, it's too late. Don't just ask "I've got xyz virus, can anyone help me". ------------------------------------------------------------------------- Table of Contents -----> Part 1 ------ -----> (1) I have a virus - what do I do? -----> (2) Minimal glossary -----> (3) What is a virus (Trojan, Worm)? -----> (4) How do viruses work? -----> (5) How do viruses spread? -----> (6) How can I avoid infection? -----> (7) How does antivirus software work? Part 2 ------ (8) What's the best anti-virus software (and where do I get it)? (9) Where can I get further information? (10) Does anyone know about * Mac viruses? * UNIX viruses? * macro viruses? * the AOLGold virus? * the xyz PC virus? (11) Is it true that...? (12) Favourite myths * DOS file attributes protect executable files from infection * I'm safe from viruses because I don't use bulletin boards/shareware/Public Domain software * FDISK /MBR fixes boot sector viruses * Write-protecting suspect floppies stops infection * The write-protect tab always stops a disk write * I can infect my system by running DIR on an infected disk Part 3 ------ (13) What are the legal implications of computer viruses? Part 4 ------ (14) Miscellaneous Are there anti-virus packages which check zipped files? What's the genb/genp virus? Where do I get VCL and an assembler, & what's the password? Send me a virus. Is it viruses, virii or what? Where is alt.comp.virus archived? What about firewalls? Viruses on CD-ROM. Removing viruses. Can't viruses sometimes be useful? Do I have a virus, and how do I know? What should be on a (clean) boot disk? How do I know I have a clean boot disk? What other tools might I need? What are rescue disks? Are there CMOS viruses? How do I know I'm FTP-ing 'good' software? What is 386SPART.PAR? Can I get a virus to test my antivirus package with? When I do DIR | MORE I see a couple of files with funny names... Reasons NOT to use FDISK /MBR Why do people write/distribute viruses? Where can I get an anti-virus policy? Placeholders ------------------------------------------------------------------------- (1) I have a virus problem - what do I do? The following guidelines will, one hopes, be of assistance. However, you may get better use out of them if you read the rest of this document before acting rashly... If you think you may have a virus infection, *stay calm*. Once detected, a virus will rarely cause (further) damage, but a panic action might. Bear in mind that not every one who thinks s/he has a virus actually does (and a well-documented, treatable virus might be preferable to some problems!). Reformatting your hard disk is almost certainly unnecessary and very probably won't kill the virus. If you've been told you have something exotic, consider the possibility of a false alarm and check with a different package. If you have a good antivirus package, use it. Better still, use more than one. If there's a problem with the package, use the publisher's tech support and/or try an alternative package. If you don't have a package, get one (see section on sources below). If you're using Microsoft's package (MSAV) get something less out-of-date. Follow the guidelines below as far as is practicable and applicable to your situation. Try to get expert help *before* you do anything else. If the problem is in your office rather than at home there may be someone whose job includes responsibility for dealing with virus incidents. Follow the guidelines below as far as is practicable and applicable. * Do not attempt to continue to work with an infected system, or let other people do so. * Generally, it's considered preferable to switch an infected system off until a competent person can deal with it: don't allow other people to use it in the meantime. If possible, close down applications, Windows etc. properly and allow any caches/buffers to flush, rather than just hit the power switch. * If you have the means of checking other office machines for infection, you should do so and take appropriate steps if an infection is found. * If you are unable to check other machines, assume that all machines are infected and take all possible steps to avoid spreading infection any further. * If there are still uninfected systems in the locality, don't use floppy disks on them [except known clean write-protected DOS boot floppies] * users of infected machines should not *under any circumstances * trade disks with others until their systems and disks are cleaned. * if the infected system is connected to a Novell network, Appleshare etc., it should be logged off all remote machines unless someone knowledgeable says different. If you're not sure how to do this, contact whoever is responsible for the administration of the network. You should in any case ensure that the network administrator or other responsible and knowledgeable individual is fully aware of the situation. * No files should be exchanged between machines by any other means until it's established that this can be done safely. * Ensure that all people in your office and anyone else at risk are aware of the situation. * Get *all* floppy disks together for checking and check every one. This includes write-protected floppies and program master disks. Check all backups too (on tape or file servers as well as on floppy). (2) Minimal Glossary [There is room for improvement and expansion here. Contributions will be gratefully accepted.] * AV - AntiVirus. Sometimes applied as a shorthand term for anti-virus researchers/programmers/publishers - may include those whose work is not AV research, but includes virus-control. (See also Vx.) * BSI - Boot Sector Infector (= BSV - Boot Sector Virus) * BIOS - Basic Input Output System * CMOS - Memory used to store hardware configuration information * DBR - DOS Boot Record * DBS - DOS Boot Sector * False Positive - When an antivirus program incorrectly reports a virus in memory or infecting a file. Scanners in heuristic mode and integrity checkers are, by definition, somewhat more prone to these. * False Negative - Essentially, a virus undetected by an antivirus program. * In-the-wild - describes viruses known to be spreading uncontrolled to real-life systems, as opposed to those which exist only in controlled situations such as anti-virus research labs. Virus code which has been published but not actually found spreading out of control is not usually regarded as being in-the-wild. * MBR - Master Boot Record (Partition Sector) * TSR - A memory-resident DOS program, i.e one which remains in memory while other programs are running. A good TSR should at least detect all known in-the-wild viruses and a good percentage of other known viruses. Generally, TSRs are not so good with polymorphic viruses, and should not be relied on exclusively. * vx - Those who study, exchange and write viruses, not necessarily with malicious intentions (So I'm frequently told here...) B-) * VxD - A Windows program which can run in the background. A scanner implemented as a VxD has all the advantages of a DOS TSR, but can have additional advantages: for instance, a good VxD will scan continuously *and* for all the viruses detected by a command-line scanner. * Zoo - suite of viruses used for testing. See the comp.virus FAQ for fuller definitions of some of these terms and others which aren't addressed here. Here are some commonly referred to anti-virus packages, including acronyms (hence their inclusion in this section). [Suggestions for expansion are, again, welcomed.] * AVP - AntiViral Toolkit Pro * AVTK - Dr. Solomon's AntiVirus ToolKit * CPAV - Central Point AntiVirus * The Doctor (Not Dr. Solomon!) * Disinfectant (Mac) * DSAVTK - Dr. Solomon's AntiVirus ToolKit * F-Prot * FindViru(s) - DSAVTK scanner * Gatekeeper (Mac) * Invircible * MSAV - MicroSoft AntiVirus * McAfee * NAV - Norton AntiVirus * SCAN - ViruScan (McAfee's scanner) * Sweep - Scanner by Sophos * TBAV - Thunderbyte AntiVirus * VET (3) What is a virus (and what are Trojans and Worms)? A (computer) virus is a program (a block of executable code) which attaches itself to, overwrites or otherwise replaces another program in order to reproduce itself without the knowledge of the PC user. Most viruses are comparatively harmless, and may be present for years with no noticeable effect: some, however, may cause random damage to data files (sometimes insidiously, over a long period) or attempt to destroy files and disks. Others cause unintended damage. Even benign viruses (apparently non-destructive viruses) cause significant damage by occupying disk space and/or main memory, by using up CPU processing time, and by the time and expense wasted in detecting and removing them. A Trojan Horse is a program intended to perform some covert and usually malicious act which the victim did not expect or want. It differs from a destructive virus in that it doesn't reproduce, (though this distinction is by no means universally accepted). A dropper is a program which installs a virus or Trojan, often covertly. A worm is a program which spreads (usually) over network connections. Unlike a virus, it does not attach itself to a host program. In practice, worms are not normally associated with personal computer systems. There is an excellent and considerably longer definition in the Mk. 2 version of the Virus-L FAQ. (The following is a slightly academic diversion) A lot of bandwidth is spent on precise definitions of some of the terms above. I have Fridrik Skulason's permission to include the following definition of a virus, which I like because it demonstrates most of the relevant issues. #1 A virus is a program that is able to replicate - that is, create (possibly modified) copies of itself. #2 The replication is intentional, not just a side-effect. #3 At least some of the replicants are also viruses, by this definition. #4 A virus has to attach itself to a host, in the sense that execution of the host implies execution of the virus. -- #1 is the main definition, which distinguishes between viruses and Trojans and other non-replicating malware. #2 is necessary to exclude for example a disk-copying program copying a disk, which contains a copy of itself. #3 is necessary to exclude "intended" not-quite-viruses. #4 is necessary to exclude "worms", but at the same time it has to be broad enough to include companion viruses and .DOC viruses. (4) How do viruses work? A file virus attaches itself to a file (but see the section below or the comp.virus FAQ on the subject of companion viruses), usually an executable application (e.g. a word processing program or a DOS program). In general, file viruses don't infect data files. However, data files can contain embedded executable code such as macros, which may be used by virus or trojan writers. Text files such as batch files, postscript files, and source code which contain commands that can be compiled or interpreted by another program are potential targets for malware (malicious software), though such malware is not at present common. Boot sector viruses alter the program that is in the first sector (boot sector) of every DOS-formatted disk. Generally, a boot sector infector executes its own code (which usually infects the boot sector or partition sector of the hard disk), then continues the PC bootup (start-up) process. In most cases, all write-enabled floppies used on that PC from then on will become infected. Multipartite viruses have some of the features of both the above types of virus. Typically, when an infected *file* is executed, it infects the hard disk boot sector or partition sector, and thus infects subsequent floppies used or formatted on the target system. The following virus types are more fully defined in the comp.virus FAQs (see preamble): * STEALTH VIRUSES - viruses that go to some length to conceal their presence from programs which might notice. * POLYMORPHIC VIRUSES - viruses that cannot be detected by searching for a simple, single sequence of bytes in a possibly-infected file, since they change with every replication. * COMPANION VIRUSES - viruses that spread via a file which runs instead of the file the user intended to run, and then runs the original file. For instance, the file MYAPP.EXE might be 'infected' by creating a file called MYAPP.COM. Because of the way DOS works, when the user types MYAPP at the C> prompt, MYAPP.COM is run instead of MYAPP.EXE. MYAPP.COM runs its infective routine, then quietly executes MYAPP.EXE. N.B. this is not the *only* type of companion (or 'spawning') virus. * ARMOURED VIRUSES - viruses that are specifically written to make it difficult for an antivirus researcher to find out how they work and what they do. (5) How do viruses spread? A PC is infected with a boot sector virus (or partition sector virus) if it is (re-)booted (usually by accident) from an infected floppy disk in drive A. Boot Sector/MBR infectors are the most commonly found viruses, and cannot normally spread across a network. These (normally) spread by accident via floppy disks which may come from virtually any source: unsolicited demonstration disks, brand-new software (even from reputable sources), disks used on your PC by salesmen or engineers, new hardware, or repaired hardware. A file virus infects other files when the program to which it is attached is run, and so *can* spread across a network (often very quickly). They may be spread from the same sources as boot sector viruses, but also from sources such as Internet FTP sites and bulletin boards. (This applies also to Trojan Horses.) A multipartite virus infects boot sectors *and* files. Often, an infected file is used to infect the boot sector: thus, this is one case where a boot sector infector could spread across a network. (6) How can I avoid infection? There is no way to guarantee that you will avoid infection. However, the potential damage can be minimized by taking the following precautions: * make sure you have a clean boot disk - test with whatever (up-to-date!) antivirus software you can get hold of and make sure it is (and stays) write-protected. Boot from it and make a couple of copies. * use reputable, up-to-date and properly-installed anti-virus software regularly. (See below) If you use a shareware package for which payment and/or registration is required, do it. Not only does it encourage the writer and make you feel virtuous, it means you can legitimately ask for technical support in a crisis. * do some reading (see below). If you're a home user, you may well get an infection sooner or later. If you're a business user, it'll be sooner. Either way you'll benefit from a little background. If you're a business user you (or your enterprise) need a policy. * don't rely *solely* on newsgroups like this to get you out of trouble: it may be a while before you get a response (especially from a moderated group like comp.virus), and the first response you act upon may not offer the most appropriate advice for your particular problem. * if you use a shareware/freeware package, make sure you have hard copy of the documentation *before* your system falls apart! * always run a memory-resident scanner to monitor disk access and executable files before they're run. * if you run Windows, a reputable anti-virus package which includes DOS *and* Windows components is likely to offer better protection than a DOS only package. If you run Windows 95, you need a proper Win95 32-bit package for full protection. * make sure your home system is protected, as well as your work PC. * check all new systems and all floppy disks when they're brought in (from *any* source) with a good virus-scanning program. * acquire software from reputable sources: 2nd-hand software is frequently unchecked and sometimes infected. Bear in mind that shrinkwrapped software isn't necessarily unused. In any case, reputable firms have shipped viruses unknowingly. * once formatted, keep floppies write-disabled except when you need to write a file to them: then write-disable them again. * make sure your data is backed up regularly and that the procedures for restoring archived data *work* properly. * scan pre-formatted diskettes before use. * Get to know all the components of the package you're using and consider which bits to use and how best to use them. Different packages have different strengths: diversifying and mixing and matching can, if carefully and properly done, be a good antivirus strategy, especially in a corporate environment * if your PC can be prevented with a CMOS setting from booting with a disk in drive A, do it (and re-enable floppy booting temporarily when you need to clean-boot). CMOS settings Some CMOSes come with special anti-virus settings. These are normally vague about what they do but typically they write-protect your hard disk's boot sector and partition sector (MBR). This can be some use against boot sector viruses but may false alarm when you upgrade your operating system. One sensible setting to make (if your CMOS allows) is to adjust the boot sequence of your PC. Changing the default boot-up drive order from A: C: to C: will mean that the PC will attempt to boot from drive C: even if a floppy disk has been left in drive A:. This way boot sector virus infection can often be avoided. Remember, however, to set your CMOS back temporarily if you ever *do* want to boot clean from floppy (for example, when running a cryptographical checksummer after a cold boot). (7) How does antivirus software work? * Scanner (conventional scanner, command-line scanner, on-demand scanner) - a program that looks for known viruses by checking for recognisable patterns ('scan strings', 'search strings', 'signatures'). * TSR scanner - a TSR (memory-resident program) that checks for viruses while other programs are running. It may have some of the characteristics of a monitor and/or behaviour blocker. * VxD scanner - a scanner that works under Windows or perhaps under Win 95, or both), which checks for viruses continuously while you work. * Heuristic scanners - scanners that inspect executable files for code using operations that might denote an unknown virus. * Monitor/Behaviour Blocker - a TSR that monitors programs while they are running for behaviour which might denote a virus. * Change Detectors/Checksummers/Integrity Checkers - programs that keep a database of the characteristics of all executable files on a system and check for changes which might signify an attack by an unknown virus. * Cryptographic Checksummers use an encryption algorithm to lessen the risk of being fooled by a virus which targets that particular checksummer. --------------------------------------------------------------------- End of a.c.v. FAQ Part 1 of 4 ------------------------------------------------------------------- (8) What's the best antivirus software (and where do I get it)? In case it's not absolutely clear from the following, I can't possibly answer the first part of this question! There are, however, some suggestions following for sources of software and of information on particular packages, comparative reviews etc. The danger of this approach is that sites, servers, and packages come and go, and I haven't time to keep track of all these variables. Some of these URLs have been passed on by trusted sources, but I haven't the time to check them all out regularly. If you run into problems, please let me know (by e-mail, please). Most of the people who post here have their favourites: if you just ask which is the best, you'll generally get either a subjective "I like such and such", recommendation of a particular product by someone who works for that company, or a request to be more specific about your needs. Some of us who are heavily involved with virus control favour using more than one package and keeping track of the market. Don't trust anything you read in the non-technical press. Don't accept uncritically reviews in the computing press, either: even highly-regarded IT specialists often have little understanding of virus issues, and many journalists are specialists only in skimming and misinterpreting. Magazines like Virus Bulletin and Secure Computing are much better informed and do frequent comparative reviews, and are also informative about their testing criteria, procedures and virus suites. Recently, a number of articles have been posted here by people who've run their own tests on various packages. These are often of interest, but should not be accepted uncritically. (No-one's opinion should be accepted uncritically!) Valid testing of antivirus software requires a lot of care and thought, and not all those who undertake it have the resources, knowledge or experience to do it properly. You may get a more informed response if you specify what sort of system you have - DOS, Windows, Win95? XT, AT, 386 or better? Is the system networked, and are you asking about protecting the whole network? (What sort of network?) Are you running NT, OS/2 or Win95, any of which involve special considerations? Be aware that there is more than one way of judging the effectiveness of a package - the sheer number of viruses detected; speed; tendency to false alarms; size (can you run it from a single floppy when necessary?); types of virus detection & prevention (not at all the same thing) offered (command-line scanning, TSR scanning, behaviour blocking, checksumming, access-control, integrity shell etc.); technical support etc. DOS packages available from SimTel etc. include F-Prot AVP Lite McAfee TBAV Most Shareware/Freeware packages can be obtained from SimTel via anonymous FTP or WWW, e.g. http://www.coast.net/SimTel/msdos/virus ftp://ftp.coast.net/SimTel/msdos/virus/ Mirror sites include: USA:- ftp.cdrom.com uiarchive.cso.uiuc.edu oak.oakland.edu wuarchive.wustl.edu ftp.uoknor.edu ftp.pht.com UK:- micros.hensa.ac.uk src.doc.ic.ac.uk ftp.demon.co.uk as well as other sites in many other parts of the world. There is some confusion at present regarding SimTel: you may find that some mirrors are still pointing to the Coast to Coast collection while others are pointing to SimTelnet. I've been referred to http://www.simtelnet.com/pub/simtelnet but haven't been able to get in to date. Of course, such products can often be obtained direct from the publisher's WWW or FTP sites too. There is a shareware program for Win95 called the Doctor. Compuserve - GO NCSAVIRUS ftp://thomnet.com/ http://www.tucows.com/files/doc9509.zip ftp://ftp.mindspring.com/users/rogert TNS BBS +1 (404) 971 8886 Also, McAfee and Thunderbyte have Win95 programs. ftp://ftp.mcafee.com/pub/antivirus/ http://thunderbyte.com/ftp/thunderbyte/ ftp://ftp.thunderbyte.com/ ChekMate is described by its author as a targeted integrity checker. It's a potentially useful shareware supplement to a good virus scanner. Via anonymous ftp at: ftp.coast.net/SimTel/msdos/virus/cm200.zip ftp.demon.co.uk/pub/simtel/msdos/virus/cm200.zip ftp.demon.co.uk/antivirus/ibmpc/av-progs/cm200.zip gate.net/pub/users/ris1/cm200.zip At the World-Wide Web site: http://www.valleynet.com/~joe/avdos.html Commercial ---------- [vendors are invited to supply full contact details and indicate the range of platforms their product range covers. Let's not overdo the hype, though, guys.] There is a pretty comprehensive list of anti-virus developers at http://www.virusbtn.com/AVLinks/ (NB Some of the following, though not shareware, can be obtained for evaluation via anon FTP or WWW. Please note, I have not tested or even seen all the packages listed here, or all the contact data, come to that, and listing here does not imply recommendation (though I won't list anything I *know* is rubbish....). DSAVTK (Dr Solomon's Anti-Virus ToolKit) [DOS; DOS & Windows; DOS & Win95; NetWare; NT; OS/2; Unix; Mac] UK Support: support@uk.drsolomon.com US Support: support@us.drsolomon.com UK Tel: +44 (0)1296 318700 USA Tel: +1 617-273-7400 CompuServe: GO DRSOLOMON Web: http://www.drsolomon.com FTP: ftp://ftp.drsolomon.com Evaluation copy of Findvirus Dos scanner available via the Web. ************* F-Prot Pro (DOS, Windows 3.x, Win95, WinNT, NetWare) There are two flavours, though I gather that Command Software and Data Fellows are currently doing joint development. Command Software Systems Inc. 1+407-575 3200 ftp://ftp.commandcom.com Data Fellows Ltd. f-prot@DataFellows.com ftp://ftp.DataFellows.com http://www.DataFellows.com http://www.Europe.DataFellows.com UK: Portcullis (for Data Fellows) 44-181-868-0098 Command Software UK 44-171-259-5710 command@command.co.uk More details inc. in ORDER-2.DOC, supplied with the shareware version. [The filename is now PRO.DOC in recent versions] ************ IBM AntiVirus: http://www.brs.ibm.com/ibmav.html 800-551-3579 (US only) 800-465-7999 fax: 800-267-5185 ************ McAfee Associates 2710 Walsh Ave Santa Clara, CA 95051 95054-3107 USA Voice (408) 988-3832 FAX (408) 970-9727 BBS (408) 988-4004 CompuServe ID: 76702,1714 or GO MCAFEE mcafee@netcom.com ftp://ftp.mcafee.com/pub/antivirus/ http://www.mcafee.com/ [DOS, Windows, Win95, NetWare] ************ NAV (Norton AntiVirus) [DOS, Windows, Win95, Mac] http://www.symantec.com/ ftp://ftp.symantec.com US Support: 541-465-8420 AOL: SYMANTEC European Support: 31-71-353-111 Australian Support: 61-2-879-6577 ************ AntiViral Toolkit Pro AVP LITE Central Command Inc. P.O. Box 856 Brunswick, Ohio 44212 Phone: 330-273-2820 FAX: 330-220-4129 BBS: 330-220-4036 WWW: www.command-hq.com/command ftp: ftp.command-hq.com pub/command/avp email: sales@command-hq.com support@command-hq.com ************ Sweep http://www.sophos.com/ ftp://ftp.sophos.com ************ Thunderbyte http://thunderbyte.com/ftp/thunderbyte/software/ ftp://ftp.thunderbyte.com (?) ************ Invircible ftp://ftp.invircible.com ftp://ftp.datasrv.co.il/pub/usr/netz/ http://invircible.com/ ************ Reflex Magnetics Ltd 31-33 Priory Park Road London NW6 7UP United Kingdom Tel+44 (0)171 372 6666 Fax+44 (0)171 372 2507 BBS+44 (0)171372 2584 Emailsales@reflex-magnetics.co.uk http://www.reflex-magnetics.co.uk/ ************ Reflex Magnetics Ireland Unit 24 Johnstown Industrial Centre, Waterford, Ireland. tel: +353-(0)51-841051 J fax: +353-(0)51-841052 http://www.iol.ie/~ralf/ ************ NH&A 577 Isham St. # 2-B New York, NY 10034 Phone: 212-304-9660 Fax: 212-304-9759 CompuServe: 72115,661 Internet: nhirsch@nha.com URL: http://www.nha.com BBS: 212-304-9759,,,,,,,3 ************ Microsoft (Macro Virus fixes) - http://www.microsoft.com For updates to MSAV, contact Symantec (but better to get a more up-to-date package). CPAV updates from the same source. There is a paper by Yisrael Radai which documents many of the problems with MSAV. ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/viruses/msaveval.zip ************ ViruSafe, ViruSafe-95 I believe a version of this program was at one time marketed by Xtree. They also maintain a Virus Hot Line via their WWW site or E-mail (virus@eliashim.co.il). ------------------------------------------------------------- EliaShim, LTD. Computer Security Specialists 5 Haganim st. Haifa 35022 Tel: +972-4-8516111 ISRAEL Fax: +972-4-8528613 Email: shimon@eliashim.co.il BBS: +972-4-8516113 URL: http://www.eliashim.com ------------------------------------------------------------- ---------------------------------------------------------------------------- VirusNet PC (DOS, Win3.x, Win95) - (File: VNPC.EXE) VirusNet LAN (DOS, Win3.x, Win95, All Networks) - (File: VNLAN.EXE) StopLight PC (DOS, Win3.x) - (File: SLELS.EXE) StopLight for Win95 (Win95, Win3.x, DOS) - (File: Check Site) StopLight for OS/2 (OS/2, Dual Boot to DOS and Win3.x) - (File: sltmos2.exe) Safetynet, Inc. 140 Mountain Ave. Springfield, NJ 07081 201-467-1024 (Sales and Support) 800-OS2-SAFE (Sales and Support in US and Canada) 201-467-1611 (Fax) 201-467-1581 (BBS 28800,n,8,1) Web: http://www.safe.net/safety/ FTP: ftp.safe.net /pub/safetynet/ EMail: support@safe.net CompuServe: GO CIS:SAFE AntiVirus and security software evals and product updates are available from the Safetynet Web, FTP, BBS and CompuServe sites. ***************** MIMESweeper (Mail scanning 'firewall') Integralis Ltd. 10 Brewery Court Theale Berkshire RG7 5AH +44(0) 1734 306060 Fax +44(0) 1734 302143 info@integralis.co.uk US Office in Kirkland, WA. Phone 206-889-4724. -------------------------------------- NetPro Computing 7150 E Camelback Rd, Suite 100 Scottsdale, AZ 85251 USA Products: * PC ScanMaster for Novell/Vines * Server ScanMaster for Banyan Vines (Use McAfee VirusScan engine) General Office: 602.941.3600 Sales: 800.998.5090 International Sales: 602.941.3630 DS Expert Info Line: 800.998.1550 Technical Support: 602.941.3670 FAX: 602.941.3610 On Line: BBS: 602.941.3620 FTP: ftp.netpro.com HTTP: www.netpro.com e-mail: info@netpro.com or 70524,2670@compuserve.com ----------------------------------------------------------------------------- There is a comprehensive set of product reviews at: http://www.first.org/virus/virrevws/ and a number of reputable vendors include comparative reviews, papers on testing etc. on their WWW/FTP servers. Virus Bulletin comparative reviews are available from http://www.virusbtn.com/Comparatives/ and information is also available on their testing protocols. There are links to just about every anti-virus site you ever heard of at http://www.innet.net/~ewillems/ In the event of a *real* tragedy, there are a number of firms which specialize in data recovery. In the UK, there are S&S International (see above) and Ontrack Data Recovery Europe (0800-243996). In the US, there's Ontrack Computer Systems (parent company of Ontrack ...Europe). I believe Maxtor also offer a service of this sort, but I have no details at present. DataRescue: http://www.datarescue.com/ info@datarescue.com Ontrack Data Recovery, Inc. 6321 Bury Drive, Suites 13-21 Eden Prairie, MN 55346 Phone: 612-937-5161 FAX: 612-937-5750 BBS: 612-937-0860 Toll free: Minnesota office: 1-800-872-2599 California office: 1-800-752-7557 Washington, DC: 1-800-650-2410 Japan: 0120-413-374 (Japan only) International: (0429)32-6365 UK office: 0800 24 39 96 (UK only) From Germany: 0130 815 198 From France: 05 90 72 42 International: +44(0)181 974 5522 Compuserve: GO DATARECOVERY W3: http:\\www.ontrack.com Email: sales@ontrack.com (9) Where can I get further information? ======================================== [I haven't checked all these: please mail me if you find any errors] ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/catalog/ ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/carobase/ ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/viruses/ [mirror sites] ftp://ftp.uu.net/pub/security/virus/ ftp://sunsite.unc.edu/pub/docs/security/hamburg-mirror/virus/ http://all.net:8000/cgi-bin/all-search-2 Virus Text Search Search engine to check out documents in the following archives: VIRUS-L Forum, 40Hex Archives, Risks Forum, Privacy Forum, CERT Advisories, Internet RFCs, State Computer Crime Laws, The Telecom Privacy Digest, CIAC Advisories, Firewalls Digest. http://www-iwi.unisg.ch/~sambucci/icaro/texts http://lipsmac.acs.unt.edu/Virus/virinfo.html http://www.valleynet.com/~joe/avinfo.html http://www.primenet.com/~mwest/av.htm http://csrc.ncsl.nist.gov/virus http://www.jumbo.com/home/dos/virus http://www.valleynet.com/~joe/top10.html ftp://ftp.uu.net/pub/virus/progs/virlab15.zip http://www.infi.net/~wtnewton/vinfo/master.html Virus-List Archive (you can also pick up the mk. II FAQ from here): ftp://cs.ucr.edu/pub/virus-l/ Virus Bulletin Home Page - vendor contact info, comparative reviews, review protocol info etc. http://www.virusbtn.com S&S International: evaluation copy of FindVirus, product info, virus encyclopaedia on-line, papers, links to other sites etc. http://www.drsolomon.com/ ftp://ftp.drsolomon.com/ ftp://ftp.sophos.com/ http://www.sophos.com/ Dr.Solomon's History of PC Viruses: http://dbweb.agora.stm.it/webforum/virus/solomhis.htm Robert Slade's Virus History: http://dbweb.agora.stm.it/webforum/virus/sladehis.htm http://www.innet.net/~ewillems/ http://www.thenet.ch/metro/ Nic Ferri has an expansive home page with many useful links http://www.agora.stm.it/htbin/wwx?fi^N.Ferri Henri Delger's home page has useful info and links HTTP://pages.prodigy.com/virushelp/ http://www.DataFellows.com/ http://www.Europe.DataFellows.com/ http://www.datarescue.com/ VSUM (not highly-rated for its accuracy) (Try SimTel mirrors, McAfee sites) Tom Simondi has written a freeware virus tutorial (VTUTOR11.ZIP). Unfortunately, I haven't been able to download it so far. http://ourworld.compuserve.com/homepages/ck http://www.slonet.org/~tsimondi/ck.htm The WildList (List of viruses currently 'in the wild' maintained by Joe Wells - doesn't include much description) ftp://ftp.ncsa.com/pub/virus/wildlist http://www.drsolomon.com/ http://www.symantec.com/virus/wl.html http://www.innet.net/~ewillems/vwild.htm AV Software Update Auto-Notification: http://www.primenet.com/~Emwest/up-form.htm Most anti-virus packages include some information on common viruses, too. Virus Descriptions ------------------ Dr Solomon's Virus Encyclopedia: http://www.drsolomon.com/virus/enc/enc.htm free-form searches from the datafellows F-Prot virus description database: http://www.datafellows.com/v-descs/ The AVP database: http://www.datarescue.com/avpbase/ Virus demonstrations -------------------- ftp://ftp.uu.net/pub/virus/progs/virsim1.zip (I haven't checked this one out yet). AVP also includes some virus demonstrations, and I know that other publishers have demos available. There are also virus simulators, which are not quite the same thing. These are sometimes advocated as a means of testing antivirus packages, but there are dangers to this approach: after all, a package which detects one of these simulators as the virus it detects is, technically, false-alarming. See section F6 of the Mark 2 Virus-L FAQ, which is rather good on types and uses of virus simulation. Books which may be of use: Robert Slade's Guide to Computer Viruses - Springer-Verlag Pretty good introduction & general resource. Computers Under Attack (ed. Denning) - Addison-Wesley Aging, but some classic texts Survivors' Guide to Computer Viruses (ed. Lammer) - Virus Bulletin Uneven, but includes useful stuff from Virus Bulletin Dr. Solomon's Virus Encyclopaedia You may from time to time find copies of an older edition of this in bookshops, though it's better known as part of Dr. Solomon's AntiVirus ToolKit. It's a pretty good guide to some of the older viruses. A Short Course on Computer Viruses (F. Cohen) - Wiley By the man who 'invented' the concept of computer viruses. Some aspects are controversial, but a good introduction to his work. The comp.virus FAQ includes pointers to some books. Useful (but expensive) periodicals: Virus Bulletin Virus Bulletin Ltd 21 The Quadrant Abingdon Oxfordshire OX14 3YS 44 (0) 1234 555139 Compuserve 100070,1340 Computers and Security Elsevier Advanced Technology PO Box 150 Kidlington Oxford OX5 1AS 44 (0) 1865-843666 a.verhoeven@elsevier.co.uk Rather cheaper (though still expensive for the non-corporate non-specialist in security) is the magazine Secure Computing. West Coast are launching a corporate licence scheme which may be of interest to corporate users Secure Computing West Coast Publishing Ltd. William Knox House Britannic Way Llandarcy Swansea SA10 6EL UK 44 (0) 1792 324000 Compuserve 70007,5406 Doubts have been expressed concerning the impartiality or otherwise of Virus Bulletin, which is a sister company to Sophos, who market Sweep and other antivirus/security products. VB uses an advisory board of anti-virus experts from a wide variety of vendors and other organisations, and its virus statistics are collated monthly from a variety of sources, not only from Sophos. Secure Computing, though formerly associated with S&S International, who market Dr.Solomon's AntiVirus ToolKit and other security products, is now an independent organization. SC also has input from experts associated with various vendors and other organisations. *************************************************************************** * As a regular and reasonably knowledgeable reader of both publications, * * I'm personally satisfied that neither displays editorial bias, nor do * * I believe that either publication intentionally weights its methodology * * to the unfair advantage of an affiliated product [DH] * *************************************************************************** (10) Does anyone know about... ============================== ...Mac viruses? --------------- The best single source of information on Mac viruses is the online help included in the freeware package Disinfectant, which can be obtained from ftp://ftp.acns.nwu.edu/pub/disinfectant CompuServe GEnie America Online Calvacom Delphi BIX sumex-aim.stanford.edu rascal.ics.utexas.edu comp.binaries.mac Information on Mac viruses is also available from the AntiVirus Catalog/ CARObase (see above). I've also noticed some Mac info at Symantec's web site (www.symantec.com). Disinfectant is an excellent anti-virus package: however, it doesn't catch much in the way of hypercard infectors or trojans, nor does it detect Word 6 macro viruses. For other mac packages, try Info-Mac mirrors like: ftp://ftp.ucs.ubc.ca/pub/mac/info-mac/vir/ The University of Texas holds the latest versions of Disinfectant and Gatekeeper, and some documentation on Mac viruses. http://wwwhost.ots.utexas.edu/mac/pub-mac-virus.html Commercial packages include SAM (Symantec) and Virex. Dr. Solomon's AntiVirus ToolKit for Macintosh is about to be released. ...UNIX viruses? ---------------- In general, there are virtually no non-experimental UNIX viruses. There have been a few Worm incidents, most notably the Morris Worm (a.k.a. the Internet Worm) of 1988. There are products which scan some Unix systems for PC viruses, though any machine used as a file server (Novell, Unix etc.) can be scanned for PC viruses by a DOS scanner if it can be mounted as a logical drive on a PC running appropriate network client software such as PC-NFS. Intel-based PCs running Unix (e.g. Linux, 386BSD, SCO Unix etc.) can also be infected by a DOS boot-sector virus if booted from an infected disk. The same goes for other PC-hosted operating systems such as NetWare. While viruses are not a major risk on Unix platforms, integrity checkers and audit packages are frequently used by system administrators to detect file changes made by other kinds of attack. However, Unix security is outside the scope of this FAQ (see comp.security.unix). [See also the comp.virus FAQ] A possibly useful book: Practical Unix Security (Garfinkel, Spafford) - O'Reilly ...macro viruses? ----------------- Macro viruses spread from files in applications which use macros capable of being infected, and are limited to the specific applications for which they were written. The macro viruses which are receiving attention currently are specific to Word 6/WordBasic and Excel: however, many applications, not all of them Windows applications, have potentially damaging and/or infective macro capabilities too. One, now widespread, infects macros attached to Word 6.0 for Windows, Word 6.0.1 for Macintosh, Word 6.0 for Windows NT, and Word for Windows 95 documents. What makes such a virus possible is that the macros are created by WordBASIC, a program language which links features used in Word to macros, and even allows DOS commands to be run. This virus, named "Concept," has no destructive payload; it merely spreads, after a document containing the virus is opened, copying itself to other documents as they are saved, without affecting the contents of documents. However, other macro viruses have been discovered, and some of them contain destructive routines. Microsoft suggests opening files without macros, to prevent macro viruses from spreading, unless the user can verify that the macros contained in the document will not cause damage. (This does NOT work for all macro viruses.) For further info on macro viruses, you might like to try http://www.drsolomon.com/ http://www.datafellows.com/macrovir.htm Richard Martin is working on an FAQ on this subject. ftp.gate.net/pub/users/ris1/word.faq or mail to Bd326@TorFree.Net Subject: PLEASE SEND FAQ ...The AOLgold virus -------------------- This is actually a trojan. The following is extracted from the CIAC bulletin (Number G-03). Apparently, an e-mail message is being circulated that contains an attached archive file named AOLGOLD.ZIP. A README file that is in the archive describes it as a new and improved interface for the AOL online service. Note that there is no such program as AOLGOLD. Also, simply reading an e-mail message or even downloading an included file will not do damage to your machine. You must execute (or run) the downloaded file to release the Trojan and have it cause damage. If you unzip the archive, you get two files: INSTALL.EXE and README.TXT. The README.TXT file again describes AOLGOLD as a new and improved interface to the AOL online service. The INSTALL.EXE program is a self-extracting ZIP archive. When you run the install program, it extracts 18 files onto your hard drive. The Trojan program is started by running the INSTALL.BAT file. The INSTALL.BAT file is a simple batch file that renames the VIDEO.DRV file to VIRUS.BAT and then runs it. VIDEO.DRV is an amateurish DOS batch file that starts deleting the contents of several critical directories on your C: drive. When the batch file completes, it prints a crude message on the screen and attempts to run a program named DoomDay.EXE. Bugs in the batch file prevent the DOOMDAY.EXE program from running. Other bugs in the file cause it to delete itself if it is run from any drive but the C: drive. The programming style and bugs in the batch file indicates that the Trojan writer appears to have little programming experience. You can get this and other CIAC notices from the CIAC Computer Security Archive. World Wide Web: http://ciac.llnl.gov/ Anonymous FTP: ciac.llnl.gov (128.115.19.53) ...the PKZip Trojan? -------------------- There have been at least two attempts to pass off Trojans as an upgrade to PKZip, the widely used file compression utility. A recent example was of the files PKZ300.EXE and PKZ300B.ZIP made available for downloading from various sources. An earlier Trojan passed itself off as version 2.0. For this reason, PKWare have never released a version 2.0 of PKZip: presumably, if they ever do release another DOS version (unlikely, at this date, in my opinion), it will not be numbered version 3.0(0). To the best of my knowledge, the latest version of PKZip is 2.04g. ...xyz PC virus? ---------------- There are several thousand known PC viruses, and the number 'in the wild' is in the hundreds. It is not practical to include information about all of these in this FAQ. However, information about some or most of those which regularly get asked about may shortly (Real Soon Now) be available in a separate document. Meanwhile, sources of information on specific viruses are included in the preceding sections. There are rarely enquiries about viruses on other computing platforms raised in alt.comp.virus, but there is some information concerning viruses on most platforms available at the Virus Test Center in Hamburg. ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/catalog/ ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/carobase/ The following sites also have virus descriptions listed alphabetically: http://www.DataFellows.com/ http://www.drsolomon.com (11) Is it true that....? ========================= (*or* some favourite hoaxes...) (1) There is *no* Good Times virus that trashes your hard disk and launches your CPU into an nth-complexity binary loop when you read mail with "Good Times" in the Subject: field. You can get a copy of Les Jones' FAQ on the Good Times Hoax from: Via FTP: ftp://usit.net/pub/lesjones/good-times-virus-hoax-faq.txt ftp://members.aol.com/macfaq/good-times-virus-hoax-faq.txt On the World Wide Web: http://www.tcp.co.uk/tcp/good-times/index.html http://www.singnet.com.sg/staff/lorna/Virus http://www.nsm.smcm.edu/News/GTHoax.html There's a Mini-FAQ available as: ftp://usit.net/pub/lesjones/Good-Times-Virus-Hoax-Mini-FAQ.txt There *is* at least one file virus christened Good Times by the individual who posted it in an attempt to cause confusion. It is more commonly referred to as GT-spoof. (2) There is no modem virus that spreads via an undocumented subcarrier - whatever that means.... (3) Any file virus can be transmitted as an E-mail attachment. However, the virus code has to be executed before it actually infects. Sensibly configured mailers don't usually allow this by default and without prompting, but certainly some mailers can support this: for instance, cc:mail can, it seems, launch attachments straight into AmiPro. [further information on this or other potentially dangerous associations would be gratefully received] There's room for a lot of discussion here. The jury is still out on web browsers: Netscape can certainly be set up to do things I don't approve of, such as opening a Word document in Word without asking. Microsoft have made available a Word viewer which reads Word files, but doesn't run attached macros. If possible, use this instead. The term 'ANSI bomb' usually refers to a mail message or other text file that takes advantage of an 'enhancement' to the MS-DOS ANSI.SYS driver which allows keys to be redefined with an escape sequence, in this case to echo some potentially destructive command to the console. In fact, few systems nowadays run programs which need ANSI terminal emulation to run, and there's no guarantee that the program reading the file would pass such an escape sequence unfiltered to the console anyway. There are plenty of PD or shareware alternatives to ANSI.SYS that don't support keyboard redefinition, or allow it to be turned off. The term mail bomb is usually applied to the intentional bombardment of an e-mail address with multiple copies of a (frequently abusive) message, rather than to the above. See SimTel/keyboard on sites carrying a SimTel mirror. (4) There is no known way in which a virus could sensibly be spread by a graphics file such as a JPEG or .GIF file, which does not contain executable code. Macro viruses work because the files to which they are attached are not 'pure' data files. (5) In general, software cannot physically damage hardware - this includes viruses. There is a possibility that specific hardware may be damaged by specific code: however, a virus which drops a particular payload on the offchance that it's running on a system with a particular type of obsolete video card seems more than usually futile. (12) Favourite myths ==================== * DOS file attributes protect executable files from infection File attributes are set by software, and can therefore be changed by software, including viruses. Many viruses reset a ReadOnly/System/Hidden file to Read/Write, infect it, and often reset it to the original attributes afterwards. This also applies to other software mechanisms such as simulating hardware write-protection on a hard disk. However, file protection rights in NetWare *can* help to contain virus infections, if set up properly, as can trustee rights. [Trustee assignments govern whether an individual user has right of access to a subdirectory: the Inherited Rights Mask governs the protection rights of individual files and (sub)directories.] Basically, a file virus has the same rights of access as the user who happens to inadvertantly activate it. Setting up these levels of security is really a function of the network Administrator, but you might like to check (politely) that yours is not only reassuringly paranoid but also knowledgeable about viruses as well as networks, since a LAN which is not, in this respect, securely configured, can result in very rapid infection and reinfection of files across the whole LAN. In particular, accounts with supervisor equivalence can, potentially, be the unwitting cause of very rapid dissemination of viruses. [See also the comp.virus FAQ (version 2) section D] * I'm safe from viruses because I don't use bulletin boards/shareware/ Public Domain software. Many of the most widely-spread viruses are Boot Sector Infectors, which can't normally infect over a serial or network connection. Writers of shareware, freeware etc. are no more prone to accidental infection than commercial publishers, and possibly less. The only 'safe' PC is still in it's original wrapping (which doesn't mean it isn't already infected...) And don't forget that shrinkwrapped software may have been rewrapped. * FDISK /MBR fixes boot sector viruses. The mark II comp.virus FAQ is worth reading on this (see Part 1 of this FAQ). In brief, don't use FDISK /MBR *unless* you're *very* sure of what you're doing, as you may lose data. Note also that if you set up the drive with a disk manager such as EZDrive, you won't be able to access the drive until and unless you can reinstall it. ****************************************************************** (i) What does FDISK /MBR do? ------------------------ It places "clean" partition code onto the partition of your hard disk. It does **not change the partition information, however. The /MBR command-line switch is not officially documented and was introduced in DOS 5.0 [It does sometimes, and when it does it us usually fatal (for the common user, anyway). FDISK /MBR will wipe the partition table data if the last two bytes of the MBR are not 55 AA.] (ii) What is the partition? ---------------------- The partition sector is the first sector on a hard disk. It contains information about the disk such as the number of sectors in each partition, where the DOS partition starts, plus a small program. The partition sector is also called the "Master Boot Record" (MBR). When a PC starts up it reads the partition sector and executes the code it finds there. Viruses that use the partition sector modify this code. Since the partition sector is not part of the normal data storage part of a disk, utilities such as DEBUG will not allow access to it. [Unless one assembles into memory] Floppy disks do not have a partition sector. FDISK /MBR will change the code in a hard disk partition sector. (iii) What is a boot sector? ---------------------- The boot sector is the first sector on a floppy disk. On a hard disk it is the first sector of a partition. It contains information about the disk or partition, such as the number of sectors, plus a small program. When the PC starts up it attempts to read the boot sector of a disk in drive A:. If this fails because there is no disk it reads the boot sector of drive C:. A boot sector virus replaces this sector with its own code and usually moves the original elsewhere on the disk. Even a non-bootable floppy disk has executable code in its boot sector. This displays the "not bootable" message when the computer attempts to boot from the disk. Therefore, non-bootable floppies can still contain a virus and infect a PC if it is inserted in drive A: when the PC starts up. FDISK /MBR will not change the code in a hard disk boot sector. Most boot sector viruses infect the partition sector of hard disks and floppy disk boot sectors: most do not infect the boot sector of a hard disk - Form virus is an exception. (iv) How can I remove a virus from my hard disk's partition sector? -------------------------------------------------------------- There are two main alternatives: run an anti-virus product, or use FDISK /MBR. Most effective anti-virus products will be able to remove a virus from a partition sector, but some have difficulties under certain circumstances. In these cases the user may decide to use FDISK /MBR. Unless you know precisely what you are doing this is unwise. You may lose access to the data on your hard disk if the infection was done by a virus such as Monkey or OneHalf. (v) Won't formatting the hard disk help? ------------------------------------ No. Formatting the hard disk can result in everything being wiped from the drive *apart* from the virus. Format leaves the partition sector untouched. There is always a better way of removing a virus infection than formatting the hard disk. [Clarification: FORMAT alters the DOS partition, but leaves the *partition sector*, aka MBR, alone.] ****************************************************************** * Write protecting suspect floppies stops infection. This sounds so silly I hesitate to include it. I've never seen it said on a.c.v., but I've heard it so often in other contexts, I've included it anyway. Write-protecting a suspect floppy will only protect that diskette from *re-infection*, if it's already infected. It won't stop an infected floppy from infecting other (write-enabled) drives. If you boot with a disk in drive A which is infected with a boot-sector virus, the fact that the diskette is write-protected will make no difference at all. Write-protecting a *clean* floppy will indeed prevent it from being infected (but see below!). * The write protect tab always stops a disk write Briefly, write protection is built into the hardware on the Mac and on the PC (and most other systems, of course, but we can't cover everything), and can't be circumvented in software. However, it is possible for the hardware to fail: it's not common, but it happens. Thus when I do a cleanup, I try to create a file on a sacrificial floppy before risking my R/O boot disk. Sometimes, I even remember.... Other caveats: a disk which you receive write-protected could have been de-protected, infected, and re-protected. Even a 3.5" disk with the write-enable tab removed can be written to by covering the hole with (e.g.) masking tape. And, of course, shrink-wrapped software could have been infected before the duplication process. * I can infect my system by running DIR on an infected disk If you have a clean PC system, you can't contract a boot sector virus *or* a file virus just by listing the files on an infected floppy. Of course, if your PC is infected, you may well infect a *clean* floppy by using DIR A: It *is* possible to have a scanner report a virus in memory after a DIR of a floppy with an infected boot sector. The distinction here is that the virus is *not* actually loaded into memory, so the PC has *not* been infected. ----------------------------------------------------------------------- End of a.c.v. FAQ part 2 ------------------------------------------------------------------- (13) What are the Legal Implications of Computer Viruses? ========================================================= ********************************************************************** The material in this section has no formal legal standing. It consists of several persons' attempts to interpret and clarify the legal issues, and cannot possibly be authoritative. ********************************************************************** Overview -------- It isn't possible to deal briefly with all the relevant legislation in one country, let alone all of them. In the USA, local statutes may be much more rigorous than federal legislation, which is, arguably, more concerned with computers in which the government has an interest than it is with those belonging to individuals. In many countries, writing of viruses is not an offence in itself, whereas in others, not only is this not the case, but distribution, even the sharing of virus code between antivirus researchers is, at least technically, also an offence. Once a virus is released 'into the wild', it is likely to cross national boundaries, making the writer and/or distributor answerable for his/her actions under a foreign legal system, in a country he/she may never have visited. Where virus writing and distribution may not apply locally in a particular case, the individual may nevertheless be subject to civil action: in other words, where you may be held to have committed no offence, you may still be sued for damage. Some of the grounds on which virus writing or distribution may be found to be illegal (obviously I'm not stating that all these grounds will apply at all times in all states or countries!) include: * Unauthorized access - you may be held to have obtained unauthorised access to a computer you've never seen, if you are responsible for distribution of a virus which infects that machine. * Unauthorized modification - this could be held to include an infected file, boot sector, or partition sector. * Loss of data - this might include liability for accidental damage as well as intentional disk/file trashing. * Endangering of public safety * Incitement (e.g. making available viruses, virus code, information on writing viruses, and virus engines) * Denial of service * Application of any of the above with reference to computer systems or data in which the relevant government has an interest. One major problem is that some residents of the United States firmly believe that U.S. law is universal law. Worse, most of them have limited knowledge of their own legal system, but this may apply to the citizens of many countries. The idea that a person can be acquitted of a criminal offence yet still lose a civil suit in connection with that same offence strikes most laymen as preposterous, yet it does happen in both Canada and the U.S., at least. Since the law does vary widely from country to country (and even within countries), it is entirely possible for one to break the law of another country, state, province, or whatever, without ever leaving your own, and since extradition treaties do exist, perhaps it's best to assume that any act that might be construed as being or causing wilful and malicious damage to a computer or computer system could get you a roommate with undesirable tendencies and no social graces. :) The best advice to give to any one contemplating a possibly illegal act would be to contact their local Crown Prosecutor, Crown Attorney, District Attorney, or whatever label the local government prosecutor wears. Acting on the advice of one's own attorney doesn't render one immune from prosecution, and the cost of defence can be high, even if successful. An extremely biased opinion is that very often attorneys attempt to provide the answer they believe the client wishes to hear, or give an opinion in areas where they have no real expertise. Prosecutors, on the other hand, tend to look at a particular action in the light of whether a successful prosecution can be mounted. If the local Crown Prosecutor were to suggest that something was a Bad Thing, I should be extremely nervous about doing it. :) USA & Canada ------------ The following is an interpretation of the laws in the USA and Canada, and has no legal standing as an authoritative document in those countries or any other. Relevant legislation in other parts of the world may be very different and in some cases far stricter. Many thanks to David J. Loundy for his assistance with the legalities regarding computer crime. A valuable source of information on this topic can be found in his E-Law paper, which can be accessed via the URL: http://www.leepfrog.com/E-Law/E-Law/Part_VII.html It is illegal in both the USA and Canada to damage data within a computer system which is used or operated by the government. This means that if you write a virus, and it eventually infects a government system (highly probable), you are in violation of the law. Inclusive in this category are damages incurred due to computer stoppages (i.e. writing a virus that causes a computer to crash or become unusable), and viruses that destroy data. The question regarding the writing of malevolent computer viruses being illegal isn't really that hard to answer: It is illegal to write and spread a virus that infects a government system. Federal law is unclear as to whether this extends to private computer systems as well, but State statutes are frequently unequivocal about defining virus-related crimes against property. The question has come up, however, about the distribution of viruses and virus-related programs. A general guideline is that it is legal to distribute viruses, for example, on a BBS, as long as the people who are downloading the virus know EXACTLY what they are getting. If you intentionally infect a file and make it available for downloading, you may be subject to prosecution. Your conscience should be your guide in this kind of a situation. If a virus distributed by you is used to damage or otherwise modify a major system, you can be held accountable. The reason that the explanations in this section are vague is that the laws in various states, provinces, etc., are different, and you should check with your local police before you decide you want to distribute viruses. If you spread a virus unknowingly, you generally cannot be prosecuted unless it can be proven that you spread the virus due to pure carelessness. The definition of carelessness has not been tested in a court of law, as far as I know at the date of writing (9/22/95) The UK ------ In the UK, the Computer Misuse Act makes it a crime to make an unauthorised modification on a computer. If you own a computer, you can authorise anything you want for that computer, so you can spread a virus on a computer you own. A virus makes a modification, so if someone deliberately spreads a virus on someone else's computer, that's a crime. Giving a virus to someone else isn't a crime if it's with his/her knowledge and permission, however. So, sending a diskette with a virus on to an AV company, together with a note saying "There's a virus on this disk, please investigate it for me" is legal. If an action is a crime, then encouraging that action can also be a crime ("incitement"). If you spread a virus unwittingly, then it isn't a crime, as you don't have "intent". If someone is negligent, and so spreads a virus (even unwittingly), then there could be a civil action for damages through negligence. The Canadian Criminal Code -------------------------- Please bear in mind that the following information was culled from the Criminal Code in 1993 and those sections may have been expanded or revised since then, or possibly some computer-specific legislation may have been enacted of which I am unaware. No mention is made in the Code (as of 1993) of computer viruses as such, but it would seem that prosecution under Sec. 430 would be appropriate. Quoting from the Code:- Section 342.1 (1) Every one who, fraudulently and without color of right, (a) obtains, directly or indirectly, any computer service, (b) by means of an electro-magnetic, acoustic, mechanical or any other device, intercepts or causes to be intercepted, directly or indirectly, any function of a computer system, or (c) uses or causes to be used, directly or indirectly, a computer system with intent to commit an offence under paragraph (a) or (b) or an offence under section 430 in relation to data or a computer system is guilty of an indictable offence and liable to imprisonment for a term not exceeding ten years, or is guilty of an offence punishable on summary conviction. (2) In this section, "computer program" means data representing instructions or statements that, when executed in a computer system, causes the computer system to perform a function; "computer service" includes data processing and the storage or retrieval of data; "computer system" means a device that, or a group of interconnected or related devices one or more of which, (a) contains computer programs or other data, and (b) pursuant to computer programs, (i) performs logic and control, and (ii) may perform other functions; "data" means representation of information or of concepts that are being prepared or have been prepared in a form suitable for use in a computer system; "electro-magnetic, acoustic, mechanical or other device" means any device or apparatus that is used or is capable of being used to intercept any function of a computer system, but does not include a hearing aid used to correct subnormal hearing of the user to not better than normal hearing; "function" includes logic, control, arithmetic, deletion, storage and retrieval and communication or telecommunication to, from or within a computer system; "intercept" includes listen to or record a function of a computer system, or acquire the substance, meaning or purport thereof. --------------- End of Sec. 342.1 --------------- Apparently the laws governing trespass have not been considered as having any application in cyberspace. Offenders under the above section would be charged with mischief, which covers a multitude of sins under Canadian law. The penalties stipulated in Sec. 342.1 are the same as the penalties for sabotage, just as a point of interest. Mischief is covered by Sec. 430:- Section 430 (1) Every one commits mischief who wilfully (a) destroys or damages property; (b) renders property dangerous, useless, inoperative or ineffective; (c) obstructs, interrupts or interferes with the lawful use, enjoyment or operation of property, or (d) obstructs, interrupts or interferes with any person in the lawful use, enjoyment or operation of property. (1.1) Every one commits mischief who wilfully (a) destroys or alters data; (b) renders data meaningless, useless or ineffective; (c) obstructs, interrupts or interferes with the lawful use of data; or (d) obstructs, interrupts or interferes with any person in the lawful use of data or denies access to data to any person who is entitled to access thereto. (2) Every one who commits mischief that causes actual danger to life is guilty of an indictable offence and liable to imprisonment for life. (3) Every one who commits mischief in relation to property that is a testamentary instrument or the value of which exceeds one thousand dollars (a) is guilty of an indictable offence and liable to imprisonment for a term not exceeding ten years; or (b) is guilty of an offence punishable on summary conviction. (4) Every one who commits mischief in relation to property, other than property described in subsection (3), (a) is guilty of an indictable offence and liable for imprisonment for a term not exceeding two years; or (b) is guilty of an offence punishable on summary conviction. (5) Every one who commits mischief in relation to data (a) is guilty of an indictable offence and liable to imprisonment for a term not exceeding ten years; or (b) is guilty of an offence punishable on summary conviction. (5.1) Every one who wilfully does an act or wilfully omits to do an act that it is his duty to do, if that act or omission is likely to constitute mischief causing actual danger to life, or to constitute mischief in relation to property or data, (a) is guilty of an indictable offence and liable to imprisonment for a term not exceeding five years; or (b) is guilty of an offence punishable on summary conviction. (6) No person commits mischief within the meaning of this section by reason only that (a) he stops work as a result of the failure of his employer and himself to agree on any matter relating to his employment; (b) he stops work as a result of his employer and a bargaining agent acting on his behalf to agree on any matter relating to his employment; or (c) he stops work as a result of his taking part in a combination of workmen or employees for their own reasonable protection as workmen or employees. (7) No person commits mischief within the meaning of this section by reason that he attends at or near or approaches a dwelling-house or place for the purpose only of obtaining or communicating information. (8) In this section, "data" has the same meaning as in section 342.1. -------------- End of Sec. 430 ----------------- For the record, from Sec. 785:- Section 785 (1) "summary conviction court" means a person who has jurisdiction in the territorial division where the subject-matter of the proceedings is alleged to have arisen and who (a) is given jurisdiction over the proceedings by the enactment under which the proceedings are taken, (b) is a justice or provincial court judge, where the enactment under which the proceedings are taken does not expressly give jurisdiction to any person or class of persons, or (c) is a provincial court judge, where the enactment under which the proceedings are taken gives jurisdiction in respect thereof to two or more justices; To the best of my limited knowledge, the Canadian Criminal Code only uses the term "incitement" in Sec. 319 (Public incitement of hatred) and Sec. 53 (incitement to commit a traitorous or mutinous act). A prosecutor would probably deal with incitement under Sec. 21 (Parties to offence), Sec. 463 (Attempts), or Sec. 465 (Conspiracy). Section 21 (1) Every one is a party to an offence who (a) actually commits it; (b) does or omits to do anything for the purpose of aiding any person to commit it; or (c) abets any person in committing it. (2) Where two or more persons form an intention in common to carry out an unlawful purpose and to assist each other therein and any one of them, in carrying out the common purpose, commits an offence, each of them who knew or ought to have known that the commission of the offence would be a probable consequence of carrying out the common purpose is a party to that offence. --------------- End of Sec. 21 ------------------ "Incite" does get mentioned in Sec. 22:- Section 22 (1) Where a person counsels another person to be a party to an offence and that other person is afterwards a party to that offence, the person who counselled is a party to that offence, notwithstanding that the offence was committed in a way different from that which was counselled. (2) Every one who counsels another person to be a party to an offence is a party to every offence that the other commits in consequence of the counselling that the person who counselled knew or ought to have known was likely to be committed in consequence of the counselling. (3) For the purpose of this Act, "counsel" includes procure, solicit or incite. -------------- End of Sec. 22 ------------------- Section 23 deals with an accessory after the fact, and I've already quoted too much, and more to come, but Sections 23.1 and 24 are interesting..... Section 23.1 For greater certainty, sections 21 to 23 apply in respect of an accused notwithstanding the fact that the person whom the accused aids or abets, counsels or procures or receives, comforts or assists cannot be convicted of the offence. Section 24 (1) Every one who, having an intent to commit an offence, does or omits to do anything for the purpose of carrying out the intention is guilty of an attempt to commit the offence whether or not it was possible under to circumstances to commit the offence. (2) The question whether an act or omission by a person who has an intent to commit an offence is or is not mere preparation to commit the offence, and too remote to constitute an attempt to commit the offence, is a question of law. -------------- End of Sec. 23.1 and 24 ---------- Under Sec. 465 (1)(c) and 465 (1)(d), conspiring to commit an offence carries the same penalties as the actual commission of the crime. Under certain circumstances, laws in other countries may be applicable in cyberspace, where there are no formal territorial boundaries. For instance, Sec. 465 (4) of the Canadian Criminal Code stipulates that every one, "while in a place outside Canada" conspires to commit an offence in Canada "shall be deemed to have conspired in Canada to do that thing." Further Information ------------------- Computer Crime (Icove, Seger, Von Storch) - O'Reilly Computer Law & Security Report (periodical) - Elsevier Advanced Technology Dr. Alan Solomon includes information on Hacking and Virus Laws in the UK and elsewhere on his webpage at http://www.ibmpcug.co.uk/~drsolly ----------------------------------------------------------------------- End of a.c.v. FAQ Part 3 of 4 ------------------------------------------------------------------- (14) Miscellaneous ================== Are there anti-virus packages which check zipped files? ------------------------------------------------------- An increasing number of packages seem to support checking .ZIP and other compression formats on the fly. DSAVTK, AVP and NAV 3.0/NAV95 support some formats. The number of formats supported may become as big a selling point as the total number of viruses detected, but for most of us it's only really an issue if we do a lot of scanning of CDs, for instance. Even then, it becomes urgent only if you *unpack* the archive and want to run programs. Compilers of CDs, however, are *not* entitled to use this as an excuse for not scanning their collections. What's the genb/genp virus? --------------------------- This is McAfee-ese for "You may have an unrecognised ('generic') boot-sector (genb) or partition-sector (genp) virus". Re-check with a more recent version or the latest version of another reputable package. Where do I get VCL and an assembler, & what's the password? ----------------------------------------------------------- Wrong FAQ. You don't learn anything about viruses, programming or anything else from virus toolkits. You want rec.knitting. B-) I can't believe there's anyone left on the Internet who doesn't know the VCL password, but I'm not going to tell you anyway. OK, maybe you want an assembler to learn assembly-language, not just to rehash prefabricated code. Where do you get TASM? You buy it from Borland or one of their agents, either stand-alone or with one of their high-level languages. If you want freeware or shareware, I guess you can still get the likes of CHASM and A86 (SimTel mirror sites in SimTel/asm). Send me a virus --------------- Anti-virus researchers don't usually share viruses with people they can't trust. Pro-virus types are often unresponsive to freeloaders. And why would you *trust* someone who's prepared to mail you a virus, bona-fide or otherwise? [A high percentage of the 'viruses' available over the internet are non-replicating junk.] Requests for viruses by people 'writing a new anti-virus utility' are usually not taken too seriously. * We get rather a lot of such requests, which leads to a certain amount of cynicism. * Writing a utility to detect a single virus is one thing: writing a usable, stable, reasonably fast scanner which detects all known viruses is a considerable undertaking. There are highly experienced and qualified people working more or less full time on adding routines to do this to antivirus packages which are already mature, and unless you have a distinctly novel approach, you don't have much chance of keeping up with them. * It may be that the research you're interested in has already been done. Say what sort of information you're looking for, and someone may be able to help. * You can't afford to use junk 'viruses' for research, and the best collections are largely in the hands of people who won't allow access to them to anyone without cast-iron credentials. If you want to test anti-virus software with live viruses, this is *not* the way to get good virus samples. Valid testing of antivirus software requires a lot of time, care and thought and a valid virus test-set. Virus simulators are unhelpful in this context: a scanner which reports a virus when it finds one of these is actually false-alarming, which isn't necessarily what you want from a scanner. Read Vesselin Bontchev's paper on maintaining a virus library: ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/viruses/virlib.zip It said in a review.... ----------------------- Reviews in the general computing press are rarely useful. Most journalists don't have the resources or the knowledge to match the quality of the reviews available in specialist periodicals like Virus Bulletin or Secure Computing. Of course, it's possible to produce a useful, if limited assessment of a package without using live viruses based on good knowledge of the issues involved (whether the package is NCSA-certified, for instance): unfortunately, most journalists are unaware of how little they know and have a vested interest in giving the impression that they know much more than they do. Even more knowledgeable writers may not make clear the criteria applied in their review. Is it viruses, virii or what? ----------------------------- The Latin root of virus has no plural form. Since the use of the word virus is borrowed from biology, you might like to conform to the usage normally favoured by biologists, doctors etc., which is viruses. However, a number of people favour the terms virii/viri, either to avoid confusion with the biological phenomenon (but what's the point of distinguishing in the plural but not in the singular?), or to avoid being mistaken for anti-virus researchers..... Where is alt.comp.virus archived? --------------------------------- It isn't, as far as anyone seems to know. No-one currently working on the FAQ is likely to offer archiving, since a full archive would include uploaded viruses. When the FAQ is established, I may do some work on making an occasional digest available. Tom Simondi points that there is an archive of sorts at dejanews. You can search for several months of messages by subject at: http://www.dejanews.com/ What about firewalls? --------------------- Firewalls don't generally screen computer viruses. However, there are currently two products that scan for viruses at a point either before or after a "normal" firewall to the Internet (or internally between post offices.) These products can scan incoming and outgoing E-mail attachments for viruses. MIMESweeper, by Integralis, uses your favorite scanner (e.g. F-PROT, Thunderbyte, Dr. Solomon's, Sophos, etc) for scanning the viruses after it has opened up the E-Mail attachments in a secure area on the hard drive of the NT machine. The use of a "batch" file allows the scanning to use any switches or commands that are available to the scanner program(s) and also allows multiple scanners to be used with different switches, etc. which it runs. If clean, it sends the E-Mail on. Files which it cannot scan are 'quarantined' in the secure area to be scanned 'by hand'. MIMESweeper ver. 2.1 reads MIME attachments, UUENCODE, and recognises ZIP and recursive .ZIP archives, OLE, but does not yet read many other compression or binary encoding formats. (CDA, BinHex, LHA and Stuffit are expected shortly). It runs under NT Workstation and requires, as minimum, a 486 with 24Mb RAM, 500Mb hard disk, and a CD-ROM drive (for installation only). It works with cc:Mail, SMTP with MIME attachments, Microsoft Mail, or MHS, and is said to be usable as a filter for other material as well as file viruses such as trojans. (MIMEsweeper will be adding FTP and HTTP later). [The following is included because Integralis' Sales Dept. in the UK don't seem to have caught up with vs. 2.1 yet.] MIMESweeper vs. 1.0 reads MIME attachments and recognises ZIP archives, but does not read other compression formats or binary encoding formats such as uuencode. Trend's InterScan VirusWall is similar to MIMEsweeper but uses Trend's own scanning engine only as the scanner. Trend also scans FTP traffic. Trend currently runs on SUN Solaris 2.4-5 and will be adding NT later. These products do real scanning before the mail hits the hard drive but, at least until the holes are filled in the above products, make sure your mail attachments, WWW downloads etc. can't be automatically executed and use a good TSR/VXD in combination with a good scanner. Note that scanning FTP traffic is likely to add a heavy network overhead and probably won't catch as many viruses as checking *all* files from *all* sources with a desktop scanner For firewall-related information, see comp.security, comp.security.firewalls, or, if you don't mind your mail by the ton, the firewalls mailing-lists. Books: Firewalls and Internet Security (Cheswick, Bellovin) - Addison-Wesley Building Internet Firewalls (Chapman, Zwicky) - O'Reilly Viruses on CD-ROM ----------------- Viruses have been distributed on CD ROM (for instance, Microsoft shipped Concept, the first (in the wild) macro virus, on a CD ROM called "Windows 95 Software Compatability Test" in 1995). It is wise to scan CD ROMs on arrival for viruses, just like floppies. If the CD ROM has compressed or archived files it is wise to scan it with an anti-virus package which can cope with large amounts of compressed and archived files. [If you scan all drives at every boot, though, you may find that this gives you a good incentive to remove CDs from your CD drive before you power down, especially if your scanner isn't set to allow you to break out of a scan. B-)] Removing viruses ---------------- It is always better from a security point of view to replace infected files with clean, uninfected copies. However, in some circumstances this is not convenient. For example, if an entire network were infected with a fast-infecting file virus then it may be a lot quicker to run a quick repair with a reliable anti-virus product than to find clean, backup copies of the files. It should also be realised that clean backups are not available. If a site has been hit by Nomenklatura, for example, it may take a long time before it is realised that you have been infected. By that time the data in backups has been seriously compromised. There are virtually no circumstances under which you should need to reformat a hard disk, however: in general, this is an attempt to treat the symptom instead of the cause. Likewise re-partitioning with FDISK. If you use a generic low-level format program, i.e. one which isn't specifically for the make and model of drive you actually own, you stand a good chance of trashing the drive more thoroughly than any virus yet discovered. Can't viruses sometimes be useful? ---------------------------------- Vesselin Bontchev wrote a respected paper on this subject: ftp://ftp.informatik.uni-hamburg.de/pub/virus/texts/viruses/goodvir.zip Fred Cohen has done some heavy-duty writing in the other direction. Start with "A Short Course on Computer Viruses", "It's Alive!"(Wiley). In general, it's hard to imagine a situation where (e.g.) a maintenance virus is the *only* option. I have yet to see a convincing example of a potentially useful virus which *needs* to be a virus. Such a program would have to be *much* better written and error-trapped than viruses usually are. Do I have a virus, and how do I know? ------------------------------------- Almost anything odd a computer may do can (and has been) blamed on a computer "virus," especially if no other explanation can readily be found. In most cases, when an anti-virus program is then run, no virus is found. A computer virus can cause unusual screen displays, or messages - but most don't do that. A virus may slow the operation of the computer - but many times that doesn't happen. Even longer disk activity, or strange hardware behavior can be caused by legitimate software, harmless "prank" programs, or by hardware faults. A virus may cause a drive to be accessed unexpectedly (and the drive light to go on) - but legitimate programs can do that also. One usually reliable indicator of a virus infection is a change in the length of executable (*.com/*.exe) files, a change in their content, or a change in their file date/time in the Directory listing. But some viruses don't infect files, and some of those which do can avoid showing changes they've made to files, especially if they're active in RAM. Another common indication of a virus infection is a change to interrupt vectors or the reassignment of system resources. Unaccounted use of memory or a reduction in the amount normally shown for the system may be significant. In short, observing "something funny" and blaming it on a computer virus is less productive than scanning regularly for potential viruses, and not scanning, because "everything is running OK" is equally inadvisable. What should be on a (clean) boot disk? -------------------------------------- A boot floppy is one which contains the basic operating system, so that if the hard disk becomes inaccessible, you can still boot the machine to attempt some repairs. NB All formatted floppies contain a boot sector, but only floppies which contain the necessary system files can be used as boot floppies. A clean boot disk is one which is known not to be virus-infected. It's best to use a clean boot disk before routine scans of your hard disk(s). Some antivirus packages will refuse to run if there is a virus in memory. It is usually better and sometimes mandatory to disinfect a system without the virus in memory, and an undetected file virus may actually spread faster during a scan, since scanners normally open all executable files in all directories. To make an emergency bootable floppy disk, put a disk in drive A and type FORMAT A: /S Be careful to avoid 'cross-formatting', i.e. formatting a double-density disk as high-density or vice versa, if you system allows this. (You should avoid this all the time, not just when creating a boot disk. I'd also recommend avoiding single-density and quad-density disks, and there may be problems writing to double-density 5.25" disks on a different machine to the one on which they were formatted, if one machine is an XT and the other an AT or better.) You can also make a pre-formatted floppy into a boot disk by typing SYS A: I'd suggest you also COPY these commands from C:\DOS to it: ATTRIB, CHKDSK (or SCANDISK if you have DOS6), FDISK, FORMAT, SYS, and BACKUP and RESTORE (or whatever backup program you use, if it will fit). They may come in handy if you can't access the hard disk, or it won't boot up. You may be aware that if there is a problem with your boot sequence, you can boot from the hard disk on a DOS 6/7/Win95 system while bypassing AUTOEXEC.BAT and CONFIG.SYS. This is not as good as a clean floppy boot: it won't help at all if you have a boot sector/partition sector infector, or if any or all of the basic operating system files have been infected by a file virus. The boot disk should have been created with the same version of DOS as you have on your hard disk. It should also include any drivers necessary to access your hard disk and other device. If, for some reason, you can't obtain a clean boot disk with the same version of DOS, you can often get away with booting from a (clean) disk using a different version, though: indeed, there are viruses which exploit a bug in recent versions of MS-DOS which will prevent a clean boot from DOS vs. 4-6. If you *do* use a different version, remember that you won't be able to use many of the standard DOS system utilities on the hard disk, which will simply return a message like 'Wrong DOS version' when you try to run them, and avoid the use of FORMAT or FDISK. If you become virus-infected it can be very helpful to have backup of your hard disk's boot sector and partition sector (also known as MBR). Some anti-virus and disk utilities can do this. Other useful tools to include are a small DOS-based text editor (for editing AUTOEXEC.BAT, CONFIG.SYS and so forth), a copy of the DOS commands COMP or FC (for comparing files), FDISK and SYS (make sure they are from the same version of DOS as you are booting). There is a school of thought that your boot disk should also include your anti-virus software. The problem with this is that anti-virus software should be updated frequently, and you may forget to update (and re-write-protect) your boot disk each time. Ideally you will have been sent a clean, write-protected copy of the latest version of your anti-virus software by your vendor/supplier. If you want to use the DOS program EDIT, remember that you need both EDIT.* and QBASIC.* on the same disk. When you have everything you need on your boot floppy and any supplementary floppies (see below), make sure they're all *write-protected*! How do I know I have a clean boot disk? --------------------------------------- You can't usually make up a clean boot disk on a system which has been booted from an infected floppy or hard disk. So how do you know you're booting clean? Actually, you can never be 100% sure. If you buy a PC with the system already installed, you can't be sure the supplier didn't format it with an infected disk. If you get a set of system disks, can you assume that Microsoft or the disk duplicator didn't somehow release a contaminated disk image? (Yes, something rather like this has indeed happened...) However, you can be better than 99% sure. * If you have (and use) a reputable, up-to-date virus scanner, it will almost invariably detect a known virus in memory (scanners can't be relied on to detect an unknown virus, in memory or not). If a good scanner doesn't ring an alarm bell, you've *almost* certainly booted clean. What constitutes a good scanner is another question.... * If you have a set of original system disks which you received shrinkwrapped *and* which you've never used *or* which have only been used write-protected, you can probably use Disk 1 as a boot disk and it *probably* isn't infected - after all, Microsoft doesn't use MSAV for jobs like this..... It has been reported, though, that DOS systems disks have been distributed infected, and the fact that they're often distributed write-enabled doesn't inspire confidence. * You could always contact the supplier of your most-trusted anti-virus utility and ask whether you can send them a boot floppy to check. Of course, even anti-virus gurus sometimes make mistakes, but a boot disk verified in this way would still be worth paying for, especially for organizations with mission-critical systems. * S&S are planning to distribute a 'Magic Bullet' disk with future versions of their Dr. Solomon product, which will boot a PC with just enough functionality to enable users to run their scanning software without infringing Microsoft's copyright (as they would be doing if they distributed a boot-able DOS floppy). This strikes me as an excellent idea. * When the unit I work for approached Microsoft to check on the legal position as regards distributing a clean boot disk with anti-virus software updates within the organization, we were told that this was OK as long as the boot floppy was made with the same version of DOS as the version on the target machine. Any organization wishing to do this might like to check with Microsoft that this is still their formal position. What other tools might I need? ------------------------------ Other suggestions have included a sector editor, and Norton Utilities components such as Disk Doctor (NDD). These are not suitable for use by the technically-challenged - any tool which can manipulate disks at a low-level is potentially dangerous. If you do use tools like this, make sure they're good quality and up-to-date. If you attack a 1Gb disk with a package that thinks 32Mb is the maximum for a partition and MFM disk controllers are leading edge, you're in for trouble.... A copy of PKZIP/PKUNZIP or similar compression/decompression utility may be useful both for retrieving data and for cleaning (some) stealth viruses. The MSD diagnostic tool supplied with recent versions of DOS and Windows is a useful addition. QEMM includes a useful diagnostic tool called Manifest. Heavy duty diagnostic packages like CheckIt! may be of use. There are some useful shareware/freeware diagnostic packages, too. Obviously, these are not all going to go on one bootdisk. When you prepare a toolkit like this, make sure *all* the disks are write-protected! Tech support types are likely to find that an assortment of bootable disks including various versions of DOS comes in useful on occasion. If you have one or two non-Microsoft DOS versions (DR-DOS/Novell DOS or PC-DOS), they can be a useful addition. DoubleSpaced or similar drives will need DOS 6.x; Stacked drives will need appropriate drivers loaded. My understanding of the copyright position is that Microsoft does not encourage you to *distribute* bootable disks (even if they contain only enough files to minimally boot the system) *unless* the target system is loaded with the same version of MS-DOS as the boot floppy. Support engineers will need to ensure that they are legally entitled to all DOS versions for which they have bootable disks. What are rescue disks? ---------------------- Many antivirus and disk repair utilities can make up a (usually bootable) rescue disk for a specific system. This needs a certain amount of care and maintenance, especially if you make up more than one of these for a single PC with more than one utility. Make sure you update *all* your rescue disks when you make a significant change, and that you understand what a rescue disk does and how it does it before you try to use it. Don't try to use a rescue disk made up on one PC on another PC, unless you're very sure of what you're doing: you may lose data. Are there CMOS viruses? ----------------------- Although a virus (e.g. antiCMOS) CAN write to (and corrupt) a PC's CMOS memory, it can NOT "hide" there. The CMOS memory used for system information (and backed up by battery power) is not "addressable," and requires Input/Output ("I/O") instructions to be usable. Data stored there are not loaded from there and executed, so virus code written to CMOS memory would still need to infect an executable program in order to load and execute whatever it wrote. A virus could use CMOS memory to store part of its code, and some tamper with the CMOS Setup's values. However, executable code stored there must first be first moved to DOS memory in order to be executed. Therefore, a virus can NOT spread from, or be hidden in CMOS memory. [There are also reports of a trojanized AMI BIOS - this is not a virus, but a 'joke' program which does not replicate. If the date is 13th of November, it stops the bootup process and plays 'Happy Birthday' through the PC speaker. In this case, the only cure is a new BIOS - contact your dealer.] [There are also reports of a trojanized 3rd-party keyboard which puts the string 'Welcome to Datacomp' to the console, if I can use such archaic terminology in a Mac context B-) - both the Virus-L FAQ versions include information on this.] How do I know I'm FTP-ing 'good' software? ------------------------------------------ Reputable sites like SimTel and Garbo check uploaded utilities for viruses before making them publicly available. However, it makes sense not to take anything for granted. I'm aware of at least one instance of a virus-infected file being found on a SimTel mirror: you can't scan a newly-uploaded file for a virus your scanner doesn't know about. Good A/V packages include self-checking code, though it's unsafe to depend even on this 100%. Be paranoid: you know it makes sense.... In general, don't run *anything* downloaded from the Internet, BBSs etc. until it's been checked with at least one reputable and up-to-date antivirus scanner. What is 386SPART.PAR? --------------------- People are sometimes alarmed at finding they have a hidden file with this name. It is, in fact, created by Windows 3.x when you configure it to use a permanent swap file (a way of allowing Windows to work as if you had more memory than you really do. On no account should you delete it, as it will upset your configuration. If you wish to remove it or adjust the size, do so via the 386 Enhanced setting in Control Panel. However, a permanent swap file usually improves performance on a machine with relatively little memory. The file is not executable as such, and reports of virus infection are usually false positives. Can I get a virus to test my antivirus package with? ---------------------------------------------------- Well, I won't send you one... Most packages have some means of allowing you to trigger a test alert. There is a standard EICAR test file which is recognized by F-Prot and Dr. Solomon's AntiVirus ToolKit, and possibly other antivirus packages. Type or copy/paste the following text into a file called EICAR.COM, or TEST.COM or whatever. X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H* Running the file displays the text EICAR-STANDARD-ANTIVIRUS-TEST-FILE. Scanning the file with one of the components of these packages should trigger an alert. There has been a long thread recently on whether the Rosenthal Simulator is useful for this sort of job. This will be considered at length here when I have the time to look at it, but it should be noted that many of the anti-virus researchers who have contributed to this document have expressed considerable scepticism. When I do DIR | MORE I see a couple of files with funny names... ---------------------------------------------------------------- Actually, this is in the Virus-L FAQ. Read that and post the question to comp.virus or alt.comp.virus if you're still worried. Basically, the answer is that MORE creates a couple of temporary files, being considerably less efficient than the Unix utility it attempts to emulate. Most versions of DOS since the Middle Ages support the syntax DIR /P, which does the same job less messily. In fact, if you have a version of DOS later than 5, you might consider incorporating it into the environment variable DIRCMD, so that it becomes your default on directory listings which exceed 1 screenful. Of course, other utilities such as ATTRIB can also be filtered through MORE like this, which may result in similar symptoms. ------------------------------------------------------------ Reasons NOT to use FDISK /MBR ----------------------------- See Section 12 in part 2 of this FAQ for further information about FDISK with the undocumented /MBR switch. However, people with virus problems are frequently advised, out of ignorance or maliciousness, to use this switch in circumstances where it can lead to an inability to access your disk drive and possible loss of data (not to mention hair and sanity). Essentially, you should avoid using FDISK /MBR unless you have it on good authority that it's safe and necessary to do so. In most circumstances, it's safer to clean a partition sector with a good anti-virus program. You should avoid FDISK /MBR at all costs under the following circumstances: 1. Under an infection of viruses that don't preserve the Partition Table e.g., Monkey, reported at 7.2% of the infections reported to _Virus Bulletin_ for December '95, the last report for which I have data 2. Under an infection that encrypts data on the hard drive and keeps the key in the MBR, e.g, One_half -- reported at 0.8% worldwide 3. When security software, e.g., PC-DACS is in use 4. When a driver like Disk Manager or EZDrive is installed 5. When a controller that stores data in (0,0,1) is in use 6. When more than one BSI virus is active, in some conditions 7. When a data diddler is active, e.g. Ripper, accountable for 3.8% of the infections reported in the study cited above (N.B.: while this case won't be fixed by AV utilities, at least one will know why there are problems with the drive) ------------------------------------------------------------ Why do people write/spread viruses? ----------------------------------- From postings which have appeared in alt.comp.virus in the past: * they don't understand or prefer not to think about the consequences for other people * they simply don't care * they don't consider it to be their problem if someone else is inconvenienced * they draw a false distinction between creating/publishing viruses and distributing them * they consider it to be the responsibility of someone else to protect systems from their creations * they get a buzz, acknowledged or otherwise, from vandalism * they consider they're fighting authority * they like 'matching wits' with antivirus vendors * it's a way of getting attention, getting recognition from their peers and their names (or at least that of their virus) in the papers and the Wild List * they're keeping the antivirus vendors in a job How seriously you take some of these assertions is up to you.... ------------------------------------------------------------ Where can I get an anti-virus policy? ------------------------------------- There is some relevant material in the Virus-L FAQ document, but you'll need to do most of the work specific to your own environment. It's worth doing some general reading on security policies generally and getting the distinctions straight between policies, strategies, standards, procedures and protocols. I'm working on this in other contexts: some of that material may eventually seep back into here. The NCSA have a Corporate Virus Prevention Policy disk/document which can be ordered via their web page (www.ncsa.com) for around $20, or downloaded from Compuserve. In the UK, the British Standards Institution have a Code of Practice for Information Security Management which includes virus-management (BS7799). BSI 389 Chiswick High Road London W4 4AL DTI (Dept. of Trade & Industry) IT Security Policy Unit 151 Buckingham Palace Road London SW1W 9SS The last time I looked at the S&S International web page (www.drsolomon.com) they had a paper on Guidelines for an Anti-Virus Policy by David Emm which is a reasonable starting point, though a comprehensive virus management policy is no small undertaking. ------------------------------------------------------------ Placeholders ------------ Errrr... gone. I don't have time to polish the FAQ at present, and leaving placeholders implied there was a likelihood of my addressing those issues in the near future. If you have suggestions for further items, I'd be glad to see them, especially if you care to do the writing. I can't guarantee a quick response, though. End of a.c.v. FAQ Part 4 of 4

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Last Modified: May 7th, 1996