Threat Description

Trojan

Details

Aliases: Trojan, Trojan:w32/[variant], Trojan.win32
Category: Malware
Type: Trojan
Platform: W32

Summary


Named after the Trojan Horse of Greek legend, a trojan is a malicious program that performs, or appears to perform, one function, but in reality executes another action without the user's knowledge or consent.



Removal


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.



Technical Details


Quite often, the trojan will either have or pretend to have a functionality that offers a useful service to the user - like a screensaver, a utility program, a service pack or application update and so on - in order to encourage the user to install the trojan.

Once the trojan is installed however, it performs its actual, unauthorized function, which ranges from mildly annoying pranks (like changing desktop icon positions), to serious, user-inhibiting functions (like disabling the keyboard or mouse) to critically destructive actions (like erasing files or stealing data). The majority of trojans today carry a payload designed to cause harm.

Trojans can be further subdivided based on how they function once they are installed onto a system, or how they deliver their payload:

About Trojan-Ransoms

A specialized type of trojan is Trojan-Ransom, which may be used to specifically identify malicious programs which attempt to steal, delete or encrypt the user's own data files; the user must subsequently 'ransom' these files back from the attacker, usually by monetary payment. For more information about this type of malware, see Article: Removing 'Police-themed' Ransomware

Generic Trojan Detections

Generic Detections are a type of detection used by antivirus programs to identify files with trojan-like behavior. Unlike single-file detections, Generics do not identify individual malware; instead, they evaluate suspect files based on their similarity to known malicious programs. If a file is similar to a previously identified threat, it is flagged as a potential security risk.

A Generic Detection may use varying naming conventions. Some examples are:

  • Trojan.Generic.3545219
  • Gen:trojan.v
  • Trojan.autorun.gen

For more information about Generic Detections, please see the Generic Detection description.






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