Trojan

Malicious program masquerading as something innocuous or useful

A trojan (or Trojan horse) is a malicious program masquerading as something innocuous or even useful. Trojans use social engineering to convince victims to execute their code, and often act in a clandestine manner, sometimes even providing the useful functionality promised while running malicious actions in secret.

The great majority of malware takes the form of trojans - software such as adware and spyware also falls into this category, as actions which are not revealed during the installation process are carried out in a clandestine manner once installed. Trojan infections can come from malicious or hijacked websites, either using social engineering to persuade victims to install the file or exploiting vulnerabilities to carry out silent drive-by downloads. Trojans may also be sent out via email spam, with the email either including an attachment (the trojan file itself), or including links to the malicious or hijacked sites mentioned previously, again using social engineering to persuade readers to visit the site. Trojans can also be spread via other communication methods such as IM or P2P filesharing, or even dropped by self-replicating malware.

Many trojan infestations involve a variety of files, each providing different functionality. Typical types of trojan include downloaders, keyloggers, backdoors, clickers and diallers.

Related news articles

Yxe trojan infecting mobile phones

Symbian software-signing slipup certifies SMS spambot.

21 July 2009

Keyloggers used to loot US county

$415,000 sneaked from local government funds.

07 July 2009

Microsoft issues emergency patch

Out-of-cycle update fixes serious, wormable flaw.

24 October 2008

Malware reaches space station

Autorun worm found on non-critical systems.

29 August 2008

Best Western database hack exposes info on 8m customers

Hotel chain data heist latest in string of major security leaks.

26 August 2008

  see all related news stories


Poll

Are you still running IE 6?
Yes, on my machine at work
Yes, on my home machine
Yes, on both work and home machines
No, I use a newer version of IE
No, I use a different browser

Leave a comment

Jobs Career Sidebar

Malware Prevalence

Agent |#######################|
OnlineGames |#################|
Kryptik |#############|
Heuristic/generic |#####|
Heuristic/generic |#####|
 View this month's full report
Virus Bulletin currently has 187,778 registered users.