|
|
Computer Viruses: Some Basic InformationWhat Are They?A computer virus is a program designed and written to affect adversely your computer by altering the way it works. They hide in your files and spread systematically from one file to another. When the infected programs are then executed (started up) the embedded virus is executed as well. A virus may do nothing other than display messages on your screen or play tricks with your desktop display. Other viruses can be more damaging. For example, some viruses make many copies of themselves, consuming system resources and slowing or halting tasks. These are often referred to as worms. Viruses can hide in the macros of such files as Microsoft Word documents or Excel spreadsheets. When these are opened they cause the virus to start its work. The virus then replicates by infecting document templates, so causing all the new files that are created with the program to have the virus too. This type is the most common being found today. Viruses may do irreversible damage, by deleting files, or by destroying the information that tells the computer where to find things on your hard disk, or even stopping the computer from working altogether. Once a virus is in a computer's memory it can infect any vulnerable file, including those stored elsewhere on a network. How are They Spread?A computer virus cannot spread from computer to computer without assistance. They spread when a computer accesses an infected file (i.e. runs a program or opens a document). Sources of infection are:
In the first 3 virus-affected files are copied on to a new computer and accessed. The last is slightly different as the virus can only become active if the computer is switched on with the infected floppy disk left in the drive. An ExampleThe ZippedFiles (or ExploreZip) worm was first reported in early June 1999. If you send an e-mail to a person whose machine is infected by the worm it tries to infect yours by sending you an e-mail that looks like this:
From: [user of
the infected machine] The attachment zipped_files.exe is the worm. If you access the attachment it infects your machine. Once this happens it will make various types of file on your machine unusable (e.g. Word documents), will try to spread to all machines on your network, and will try to spread to others by sending out e-mails with the attachment. What Can I Do About Them?
Virus HoaxesIn addition to the viruses themselves there is also a problem with virus hoaxes. These are sent as e-mails. This is a typical example: If you receive an e-mail titled "PLEASE HELP POOR DOG. Win A Holiday" DO NOT open it. It will erase everything on your hard drive. Forward this letter out to as many people as you can. This is a new, very malicious virus and not many people know about it. This information was announced yesterday morning from Microsoft, please share it with everyone who might access the Internet Other recent hoaxes have warned about viruses with names like, Good Times, Join the Crew and It takes guts to say 'Jesus'. The characteristic elements of a hoax e-mail such as the one above are:
When you see such language in an e-mail, it is probably an hoax. If you are unsure check the e-mail against one of the Web sites dealing with viruses and virus hoaxes. Do not forward it! The important points to remember about these hoaxes are:
Web SitesAnti-virus software:There are a number of anti-virus packages manufacturers. Here are links to the Web sites of some of the best known:
F-Secure
(http://www.f-secure.com) General and hoax information:Most anti-virus package manufacturers have the latest information about viruses and virus hoaxes on their Web sites. An example is the F-secure site:
http://www.f-secure.com/v-descs/ and
http://www.f-secure.com/virus-info/hoax/ Current Threats
|
Send mail to
webmaster@repair-my-computer.co.uk with
questions or comments about this web site.
|