How are viruses passed through email

Asks danmiller103

A. Most viruses are passed through email - usually through an attachment, which once opened runs a macro or visual basic script on your computer. This basically means that it deletes files from your hard drive, usually of a certain type. Some of the cleverest viruses don't even have to be opened to create havoc on your PC, and once you are sent one of these there is not much you can do to stop it. And as you probably know, some of the most annoying e.g. the I love you virus, forward an email onto everyone in your address book, so that the virus is automatically passed on.

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Q. What types of email account does it hit

A. The most popular email accounts that viruses target are those supplied by Microsoft's Outlook or Outlook Express. This email facility is supplied free of charge by Microsoft and is therefore very popular - and a target for hackers.

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Q. Can you recommend any other free email accounts

A. Hotmail - is popular and also free to use. However, it is also a Microsoft product so could be targeted by some viruses.

ZDnet -� ZDnet offers free web-based email accounts that include the ability to gather mail from other POP accounts, filter incoming messages, and reply with an autoresponder when on holiday.

Yahoo! - Yahoo is another popular email account; it is free and offers spam filtering and collection from other POP email accounts.

Lycos - Lycos is also free and web-based and offers the facility of message forwarding.

AltaVista - Another popular alternative, AltaVista has been around for some time and is very user friendly.

Netaddress - A less well-known email account, netaddress is user friendly and offers an auto forward facility from other email accounts.

Eudora - Eudora 5.1 is becoming increasingly popular and is easy to use - its interface is similar to that of Outlook Express so is fast becoming a common alternative.

Pegasus Mail �- Pegasus was the first web-based free email account provider on the web, so it really knows how to go about hosting your email. It is very easy to use, and lets you send bulk email to all your friends at once.

AOL Mail - This is a high quality free email service that is very secure and also lets you access mail you've deleted by mistake.

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Q. How would I stop a virus sent to me on email from spreading through my PC

A. If you are lucky enough to be sent an email virus that needs to be opened before it is kick-started then avoid switching it on. Delete any suspicious email and do not open them. In general avoid opening any attachments if you don't know who the email is from. In particular, avoid opening any file that ends with EXE, SHS or VBS as it can contain a virus. Alternatively, you can install virus software, which should pick up any incoming viruses.

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Q. Can you recommend some good anti-virus software

A. Some leading software for 2001 include the following programmes:

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Symantec's new Norton Anti Virus 2001 software is very good and costs about �30, it is very easy to install and automatically checks for fresh viruses when you log on to the Internet.

McAfee Virus Scan 5.11 is a good programme, but you really need to use the manual to install it, if you have some computer knowledge this is easy but not a good tool for absolute beginners. It costs about �24.

Grisoft's AVG Gold Anti Virus software costs �20 and comes with two years free updates.

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Q. How does anti virus software work

A. A good anti virus software package will use a combination of techniques to detect a virus. One such technique is pattern matching (used to attack known viruses) whereby the anti virus program scans a file by looking for a sequence of bytes within the programme code (called a fingerprint or pattern) which uniquely identify the virus. But as there are thousands of viruses out there it is not an efficient technique on its own. In addition to this, a number of polymorphic viruses exist which rearrange the code bytes of a virus each time it infects a file, or use encryption that can make detection even more difficult. Such a technique is very thorough, but it only detects viruses it knows about, so are always out of date. It is best to run an anti virus program that can also detect unknown viruses, this type of software will check files via inoculation - basically it checks whether a file has changed (all files will change when infected). This system also has some limitations in that it does not always detect macro viruses. Heuristic scanning is the best method of detecting macro viruses as its software analyses the program code to see if it has any features common to known viruses, the more common features found in a scan the more likely it is to carry a virus. All leading anti viral programmes will use a combination of these methods to detect viruses.

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Q. Is there more than one type of virus

A. There are several types of virus - the most�common are called worms, Trojan horses, macros, VBS's, hactivism and hacker agents.

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Q. What do these terms mean

A. Worms: A worm virus is self-replicating. It eats into your PC and copies itself continuously on your computer, using up memory. It can attach itself to email, and automatically mail your entire address book.

Trojan horse: installs software onto your computer that allows someone else access to information on your computer, from another computer.

Macros: viruses hide within computer software that have macros e.g. word processing and spreadsheet software - the most popular of which are Microsoft Word and Excel - and are activated when you open files.

VBS: Visual Basic Script or VBS is the programme environment inside a Microsoft programme that allows users to change preselected pieces of code using a graphical interface - if accessed by a hacker it can make creating a virus very easy indeed.

Hacker agent: similar to a Trojan horse - it allows someone else - a remote user - to have access to your computer. They can pretend they are you!

Hactivism - is a term that has been coined to hackers that send viruses with a political message.

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Q. What are the most common email viruses

A. Homepage: this is a worm virus that is sent by email. The subject line says Homepage.HTML and the message invites you to check out the homepage and once you open it, it emails your entire address book.

Anna Kournikova: due to the popularity of the tennis star of the same name, this email attachment has been opened by thousands of (usually) men hoping to see a picture of Anna Kournikova. It is a worm virus, but it does not do much harm to your computer.

Kakworm: attaches itself to Outlook Express and uses the signature feature to attach itself to outgoing messages - it works without an attachment being run.

Navidad -the subject line of this virus is Navidad.Exe - it is a dangerous worm virus that can wreck your PC, so if you receive it do not open it, just delete it.

Creative - this is a really annoying virus as it moves all your zip, sound and image files to a new location and renames them - so that they can become impossible to find. However it is easy to identify as its subject line reads "a great shockwave flash movie."

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By Karen Anderson