Internet trojan horse programs, spyware, keyloggers, rootkits, pseudorootkits, hijackers, adware, annoyware, email relays, spam proxies, spam relays, scam downloads and email/spam robots ("bots") are perhaps the greatest security threat to individuals and institutional networks in existence.
By installing malware (short for MALicious softWARE) on a machine, computer crackers can go anywhere, see and do anything they want with your computer, including banking records and your most intimate and personal documents.
In addition to wreaking havoc with your machine and pillaging your personal property, some malware, specifically trojan horse servers, can even record your personal conversations if you have a microphone connected to your computer. Malware can invade your system without you ever knowing it and are designed to elude firewalls by using ports which are not blocked by network "firewall" security software or proxy servers. Many of them disable the most frequently used antivirus and software firewalls