Named after the Trojan Horse of Greek legend, a trojan is a program or file that has, or appears to have, a useful or desirable function to encourage the user to install the program or open the file. In the background however, it also silently performs unauthorized actions (its payload), without the user's knowledge or consent.
Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.
Security programs will sometimes unintentionally identify a clean program or file as malicious if its code or behavior is similar to a known harmful program or file. This is known as a False Positive. In most cases, a False Positive is fixed in a subsequent database release.
Usually, updating your F-Secure security product to use the latest database is enough to resolve the issue. You can check by first updating your F-Secure security product to use the latest detection database updates, then rescanning the file.
After checking, if you still believe the file is incorrectly detected, you can submit a sample of it to F-Secure Labs for re-analysis.
NOTE If the file was moved to quarantine, you will need to first collect the file from quarantine before you can submit it.
If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.
Find the latest advice in our Community Knowledge Base.
See the manual for your F-Secure product on the Help Center.
Submit a file or URL for further analysis.
A trojan is usually deliberately designed by its author to appear authentic and attractive. For example, it may appear to be a screensaver, a service pack, an application update and so on.
Trojans rely on tricking the user into believing that the program is authentic, so that they unwittingly install the program themselves. To do this, most trojans mimic or entirely copy the style and branding of popular legitimate programs or files. Some trojans (particularly on the Android platform) are actually copies of legitimate apps that have been repackaged or trojanized to include harmful components.
Trojans are often distributed using the same (or very similar) names and designs as popular programs, to increase the chances that users will mistake the trojan for the legitimate app and install it instead.
Once installed or opened, the trojan may perform its promised function, or display a decoy document to distract the user. In the background however, it also silently performs unauthorized actions (its payload), without the user's knowledge or consent.
Depending on its creator's intent, a trojan's payload can range from:
It is often very difficult for users to realize that a trojan is performing harmful actions, as they are usually well camouflaged to keep the system from triggering any notification messages that might arouse the user's suspicions.
Trojans are often classified into sub-types based on the actions they perform. These are just a few of the possible types:
A specialized type of trojan is ransomware, which attempts to steal, delete or encrypt the user's own 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:
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