Computer viruses are called viruses because they share some of the traits of biological viruses. A computer virus passes from computer to computer like a biological virus passes from person to person. There are similarities at a lower level as well. A biological virus is not a living thing. A biological virus is a fragment of DNA inside a protective jacket. Unlike a cell, a biological virus has no way of infecting or to reproduce by itself. Instead, a biological virus must inject its DNA into a cell. The viral DNA then uses the cell's existing machinery to reproduce itself. In some cases, the cell fills with new viral particles until it bursts releasing the virus. In other cases, the new virus particles bud off the cell one at a time, and the cell remains alive.

A computer virus shares some of these traits. A computer virus must piggyback on top of some other program or document in order to get executed. Once it is running, it is then able to infect other programs or documents. The analogy between computer and biological viruses obviously stretches things, but there are enough similarities that the name sticks.

You can protect yourself against viruses with a few simple steps:

  • If you are worried about traditional (as opposed to e-mail) viruses, you should be running a secure operating system like Linux or Windows NT. The security features on these operating systems are designed to keep viruses as well as unwanted human visitors out.

  • If you are using an unsecured operating system, buying virus protection software is a great safeguard. UNH personel can visit the UNH virus protection website at: UNH Virus protection web site. Here you can learn about the latest virus warnings ands hoax alerts, as well as download anti-virus software with current virus definition data files.

  • Another method of avoiding viruses is by avoiding programs from unknown sources (like the Internet). Sticking with commercial software purchased on CDs eliminates almost all of the risk from traditional viruses.

  • Insuring all unknown floppy disks are checked for viruses prior to use. This will eliminate the risk of a boot sector virus coming in from a floppy disk. Disabling floppy disk booting on your system is another more extreme option.

  • You should make sure that Macro Virus Protection is enabled in all Microsoft applications, and you should NEVER run macros in a document unless you know exactly what they do. There is seldom a good reason to add macros to a document. Avoiding all macros is a great policy.

In the case of the ILOVEYOU e-mail virus, the only defense is personal discipline. You should never double-click on an attachment that contains an executable that arrives as an e-mail attachment. Attachments that come in as Word files (.DOC), spreadsheets (.XLS), images (.GIF and .JPG), etc., are data files, and they can do no damage. A file with an extension like EXE, COM, or VBS is an executable, and an executable can do any sort of damage it's programmed to do. Once you run an executable, you have basically given the executable permission to do anything on your machine. The only defense is to never to run executables that arrive via e-mail.


© 2011 University of New Hampshire Office of Research Computing and Instrumentation
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