Like the wooden horse of legend that the Greeks used to infiltrate the city of Troy, a
program poses as one thing yet actually contains another. Like a virus, a Trojan requires an executable program that the user launches to initiate infection. Often, a Trojan appears to be a harmless game, utility, or program, but when a
Crackers use Trojans to spread viruses and worms, to install
and spy- ware, or to steal and destroy data. The
or purpose of a Trojan varies from program to program. Some computer worms create Trojan files containing copies of
The best way to protect yourself against Trojan programs is to avoid launching executables received in your e-mail and to install and maintain a computer antivirus program. If you download any software from the Internet, scan it to make sure it isn’t infected before you install or launch it.
In 1988, Robert Morris, a graduate student at Cornell University, created and released the Morris Internet Worm, a self-replicating program that spread throughout the Internet. The worm replicated out of control and crashed more than 6,000 computers (
To put the effect of the Morris Worm in perspective, the Internet was much smaller in 1988. At that time, commercialization of the Internet had just occurred, and most Internet users were at universities and government agencies. In 1988, the Internet had approximately 56,000 connected machines; by 2004, the number of machines is
|On The Web||
A company called the Internet Systems Consortium conducts a biannual survey of Internet hosts. For more information about the Internet Systems Consortium and the data that it collects, visit www.isc.org .
In contrast to a computer virus, a
is an autonomous program that can spread across networks and replicate without
To access and
Some worms spread
You can sufficiently protect your computer from worms by taking the following
Install antivirus software, and update the software regularly
Install software and operating system updates as soon as they are available
Don’t open suspicious e-mail attachments, even from people that you know
Antivirus software will detect and eliminate worms in e-mail attachments, on your hard drive, and in your computer’s memory. Update your antivirus software’s definitions regularly so that they remain current and can adequately defend your computer. If the software has an automatic update feature, activate it. This will make it more likely that your antivirus program will
Because most worms exploit vulnerabilities in applications and system software, patching these software
As a reminder, if you reinstall your system software or applications, be sure that you also
Just as I said for viruses, don’t open suspicious e-mail attachments, even if they appear to be from someone you know. Often, an executable file can be disguised as what appears to be a harmless document; so, don’t open something thinking it’s safe just because it doesn’t end in . exe .
Crackers often attempt to trick users into launching Trojans by
Microsoft does not send patches via e-mail to any of its customers — so, don’t be fooled. Because there are hundreds of millions of people using Microsoft products, it is