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A malicious program or piece of code
contained within an apparently harmless program. Trojan horses are often
installed inadvertently by people receiving, for example, electronic
greeting cards by e-mail. Some Trojans simply damage data on hard
disks or perform various kinds of mischief, such as dis-playing odd messages
on the computer screen. More sophisticated modern versions can open up a
computer to attack from the internet, allowing a cracker or script
kiddie with the right software to effectively take over control of the
machine. One famous Trojan horse program, Back Orifice, was created by a
hacker group, Cult of the Dead Cow, to illustrate security holes in
Microsoft operating systems. Other common examples are Netbus and
SubSeven. Many anti-virus programs now routinely scan for the
well-known Trojans, and some personal firewalls prevent them from
advertising their presence to potential intruders. |
