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Anti-Virus

What Is A Virus?

Viruses have changed substantially over the last few years. Where once they would hide in the boot sector of a floppy disk, they now e-mail themselves to you. Back in the distant past where a slow modem and text based e-mail were all that was available, being infected by a virus was considered clumsy. Back in those days of the 286 and 386 processors, anti-virus software was only updated every couple of weeks, and it placed such a load on the slow processor, that most chose to avoid it anyway. Then came the Internet boom. In the past, if you had a computer and a modem you were probably quite technical and aware of the threats out there, nowadays the majority of the population has access to the Internet, its wealth of information, and threats. As at the end of 2001 there were in excess of 70,000 known viruses, and more are being created daily. Estimates suggest that during that year, one in every 370 e-mails contained a virus, given that this is up from one in 700 the year before, the likelihood is that over the course of this year, you will receive at least one virus in your e-mail

Ironically the same cheap, fast Internet access which we enjoy via blueyonder and others is what allows modern viruses to propagate so quickly. On a slow modem dial up service, if your PC spent half an hour e-mailing viruses to all and sundry, you would quickly notice and take preventative action. Over an always on broadband connection, your entire address book could be bombarded with viruses in the blink of an eye. It is your responsibility, as a good citizen of the Internet, to make sure that your system is appropriately protected, and that you will not be e-mailing viruses to your friends.

Luckily as PCs have become more powerful, Anti Virus packages have become more lean, allowing you to have a virus scanner running in the background at all times, providing constant protection, by scanning each file before you open it.

I Keep Hearing About Trojans, And Worms, What Are They?

The following has been shamelessly plagiarised from F-Secure. Visit their web site for an up to date version.

  • Virus
    A computer program that replicates by attaching itself to another object.

  • Trojan Horse
    A program with hidden destructive functionality.

  • Worm
    A computer program that replicates independently by sending itself to other systems.

  • Polymorphic virus
    A virus which changes itself (mutates) as it passes through host files, making disinfection a serious challenge.

  • Stealth virus
    A virus that hides itself by intercepting disk access requests. When an anti-virus program tries to read files or boot sectors to find the virus, the stealth virus feeds the anti-virus program a clean image of file or boot sector.

  • Replication mechanism
    A mandatory part of every virus and worm. If it doesn't have a replication mechanism, it's by definition not a virus or worm.

  • Time bomb
    Destructive action triggered at some specific date or time.

When Is A Virus Not A Virus?

When its a hoax. Have you ever seen a newsgroup or e-mail message telling you about a new virus, urging you to pass the message on. A good proportion of these are hoaxes. Most anti virus pages now have a hoax page to reassure people that the warnings are not true. Always check these out before forwarding warnings about viruses. See Jellyroll's Gullibility Virus Page and Vmyths

How Do I Check If I Have A Virus?

There are many on-line virus-checkers. Trend Micro offer House Call which checks your system over the Internet. McAfee have something similar - but I've never used it so I can't comment. While these packages are fine for occasional checks, the best solution remains to go out and buy a good virus-checker. Nowadays they come with a life-time of Internet updates. See the list at the foot of the page for links, or visit West Coast Labs Check Mark or the Virus Bulletin 100% Awards for ratings and reviews of the various programs.

How Often Should I Update My Virus Checker?

I update my antivirus program once a month. New virus patterns can check for the latest viruses. As soon as a new virus hits the Net, most major companies are working on a way to clean them and new virus pattern files are released fairly quickly. Then it is a good idea to update your antivirus program straight away or at least check the web site for your program. Some packages offer an automatic update feature, if yours has this, set it to check for updates daily and you will always have the most up to date protection.

Can I Get A Virus Via E-Mail?

The answer used to be no, you could receive a virus infected attachment by e-mail, but as long as you didn't open it you were safe. Unfortunately Microsoft Outlook and Outlook Express changed this. In order to allow e-mail to look more interesting (everything from text formatting such as bold, underline etc. to pictures) Microsoft allowed Outlook to use parts of Internet Explorer in order to display messages, thus opening a number of security holes. May 2001 saw the first exploitation of one of these holes with the widely publicised Lovebug virus. While technically basic this virus caused havoc across the Internet because of the number of people using Outlook, and the inability of Anti Virus packages at the time to detect it. As a last resort, many government agencies and large corporations were actually forced to shut down their e-mail servers to prevent further infection.

To protect yourself from e-mail viruses, either stop using Outlook / Express and try an alternative package such as the excellent Pegasus mail. Or, if you like Outlook, or are simply unwilling to change be sure to visit Windows Update regularly in order to download any security patches for your system, and of course update your virus scanner frequently.

Where Can I Find Out More About Viruses?

Most of the Anti Virus vendors below have good up to date information on their web sites. Some sites are more technical than others, so take a look at a few, and choose your favourite.

Home Network Security

http://www.cert.org/tech_tips/home_networks.html

Download Sites For Anti-Virus Programs

NB: Most of these programs below offer a free, fully functional version for download and use for 30 days.

The list below includes some of the most popular AV Packages available. This should not be seen as an endorsement of these products.

Last Amended : 2004-03-13 by elfin
Original Author : Angua

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