Worms: malware that spreads through network connections.
Viruses: malware that spreads from computer disks, CD-ROMs, and other storage media.
There are many types of malware, including: Malware is a shortened term for "malicious software." Malware is software designed to infiltrate or damage a computer without the owner's consent or knowledge. Sometimes these attachments contain destructive viruses, Trojan horses, or spyware, sent intentionally by someone who intends to cause harm or steal sensitive personal information. Naturally, some of these files will be Trojan horses, so the moment an unwary user downloads and runs them, the programs are free to cause whatever damage their writer intended.Every day you receive email messages with attached documents, photos, or other electronic files. Rather than post a Trojan horse to somebody else's website, some people set up their own websites and pretend to offer hacker tools or pornographic files for others to download. So, even though deleting a Trojan horse may be easy, finding and deleting all copies of that Trojan horse will be time-consuming, difficult, and nearly impossible. However, between the time that the Trojan horse was posted and the time the website administrator deletes it, many people could have downloaded the Trojan horse and passed it along to others. Of course, as soon as the website administrator discovers the existence of the Trojan horse, she can delete it to prevent others from downloading it. Since website operators rarely have time to thoroughly examine every file posted, an occasional Trojan horse can slip through the checking procedures unnoticed. These communal gathering spots on the Web give Trojan horse writers a degree of anonymity along with the chance of attacking as many random victims as possible. Trojan horses are commonly found on websites that offer free software, such as shareware programs. Once someone has written a Trojan horse, the next step is to spread it by copying it onto a victim's computer, posting it on a website for others to download, sending it as a file attachment via email, distributing it through IRC and online service chat rooms, or sending it through ICQ and other instant messaging services. Since most users won't suspect that a program from a large, well-known publisher would contain a Trojan horse, the victim is likely to run the linked program containing the Trojan horse. To do this, malicious hackers have created special wrapper or binder programs with names like Saran Wrap, Silk Rope, or The Joiner, which can package any Trojan horse inside another program, thereby reducing the likelihood that someone will discover it. Since few people knowingly run a malicious program, Trojan horses must disguise themselves as other programs that the victim believes to be harmless (such as games, utilities, or popular applications).īesides disguising themselves as harmless programs, Trojan horses can also disguise themselves inside a legitimate program, such as Adobe Photoshop or Microsoft Excel.
Before a Trojan horse program can attack, it must first find a way to entice the victim to copy, download, and run it.