Algorithm used in detecting trojan horse?

can any 1 plllllllllllllllllllll tel me wats the algorithm used in anti-trojans to detect trojans.

Its bit urgent want it asap

hope u ppl wil help it out in this

thanks in advance

Algorithm used in detecting trojan horse?nortan antivirus

Fixed vs. variable-length patterns for detecting suspicious ...The algorithm used to create fixed-length patterns is slightly different and ..... In our case, we have developed a Trojan horse that does no de- ...

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Virus and malware with anti-virus and removal information.Lekbot is a Trojan horse that is written in Perl which can be used to perform a .... Bloodhound technology consists of heuristic algorithms used to detect ...cat:ML%26Lifestyle http://wwapak.blogspot.com

Algorithm used in detecting trojan horse?nortonantivirus

Most of the fast tools use mix of file name/file location and file signature and compares it with the one in their bad file database. This approach usualy finds all the common trojans. usually md5 is used as file signature, though there are some variations of this approach.

Another approach is used by anti-virus applications, which scan computer longer and also searches files for specific paterns or dangerous sequences in their code ( heuristics approach). It's slower, but might detect trojans that are new or change their code often.

Third approach is looking at specific points in the system and waiting if program is trying to access it. For example, downloading and installing additional sofware, or changing some your PC settings. This one is used in real-time protection software.