VIRUS TIP SHEET

What is a virus?

• A virus is potentially destructive software that moves from program to program or from disk to disk.
• Viruses need a host to infect.

How do I get viruses?

• You get a virus from executing an infected program or disk. Most viruses come from infected disks.
• Viruses want to spread as far as possible before anyone detects them.

What are types of destructive programs?

• Viruses enter programs from external software sources. There are different types as: Boot sector, file infecting, etc. They are destructive in nature
• Worms are self-reproducing. They create copies of them selves and eventually create so many copies of themselves that they bog down the system. They do not infect the program.
• Trojan Horses are destructive programs that have been disguised. They copy themselves to other programs and attach themselves. They can be inviting and later do their damage – hence the name. They can even be programmed to self-destruct.
• Logic Bombs are similar to Trojan Horses but they are designed to activate on a specific date and time, number of times executed, or a random number.

How can I avoid viruses?

• Use a secure system like UNIX or a virus protection program.
• Avoid programs from unknown sources on the Internet and use commercial cd’s.
• Write-protect a floppy diskette.
• Scan all disks for viruses, even new shrink wrapped software!
• Disable floppy disk boots – most computers allow you to do this today. This eliminates the risk of a boot sector virus coming from a floppy disk accidentally left in the drive.
• Make sure that Macro Virus Protection is enabled in all Microsoft Applications. – Never run a macros document unless you know what they do.
• Open Microsoft Word or Excel as a viewer program.
• Never double click on an attachment that contains an executable that arrives as an email attachment, unless you know what the attachment is. EXE, COM, or VBS are all executable and do damage. Words files as doc. and spreadsheets as xls. are data files and do not do damage.
• Be aware of hoaxes. The virus warning could actually be the virus! Check the validitiy of a virus at Cert Coordination Center – http://www.cert.org or

McAfee Virus Information Library – http://vil.mcafee.com .

• Continue to educate yourself about viruses.