What are viruses, worms, and Trojan horses?
A virus is a program created specifically to invade computers and networks and wreak havoc on them. The mischief caused can be very minor, such as causing a funny image or cryptic message to be displayed on your screen, or it can do some serious damage by altering or even destroying files. A worm is slighty different in that it is self-contained and does not need to be part of another program to propagate itself. A Trojan Horse is a malicious program that pretends to be a legitimate application; it purposefully does something the user does not expect. Trojans are not viruses since they do not replicate, but Trojan horse programs can be just as destructive.
Return to sender Recent security threats, such as MyDoom, have spread through e-mails disguised as e-mail error messages that look familiar.The attached file appeared to be the text of a message you might have sent to the wrong address, but if you opened it you fell victim to the virus. No matter how authentic an e-mail appears to be, make sure you know the contents of the attachment before you open it. Help protect against viruses, worms, and Trojan horses Although viruses, worms, and Trojan horses have very different characteristics, there are three main ways you can help protect yourself against all of them. Step 1: Never open an e-mail attachment from a stranger. Step 2: Never open an e-mail attachment from someone you know, unless you know exactly what the attachment is. Step 3: Always keep your antivirus software up-to-date.
A computer virus is a small program written to alter the way a computer operates, without the permission or knowledge of the user. Some viruses are programmed to damage the computer by damaging programs, deleting files, or reformatting the hard disk. Others are not designed to do any damage, but simply to replicate themselves and make their presence known by presenting text, video, and audio messages. Viruses often cause erratic behavior and can result in system crashes and data loss. Trojan Horses are impostors–files that claim to be something desirable but, in fact, are malicious. A very important distinction from true viruses is that they do not replicate themselves, as viruses do. Trojans contain malicious code, that, when triggered, cause loss, or even theft, of data. In order for a Trojan Horse to spread, you must, in effect, invite these programs onto your computers–for example, by opening an email attachment. Worms are programs that replicate themselves from system to system
