HEUR: Trojan message - this is how you proceed

If you receive a message from your anti-virus software with the terms "HEUR" and "Trojan", that sounds very threatening. But you still don't know what's behind it. We'll tell you on this page.

Trojan horse: Virus report with "HEUR" - what is it?

• The abbreviation "HEUR" stands for heuristic. Virus detection is a process used to identify previously unknown viruses as such.
• Almost every virus scanner and anti-virus system also use heuristic analysis. A virus is only classified as dangerous based on the code and its behavior.
• A heuristic find can thus actually represent a previously completely unknown virus, but it can equally well be a false alarm.

Heuristics: Virus danger or not?

• If such a heuristic message appears from your anti-virus software, the file ends up in quarantine in most programs. Here you can see the path of the file (instructions for Avira AntiVir and the procedure for Avast).
• If the path and file appear safe and known to you, you can unlock the file again. If you do not know about the file, you should leave it in quarantine.
• Within the quarantine, the file remains isolated and can no longer do anything. If it turns out in the coming days or weeks that the file is required by a program, you can still activate it.
• If you would like to additionally check your system for other viruses, it is often worthwhile to use an independent virus scanner. The free Malwarebytes Anti-Malware software is extremely reliable in detecting and removing viruses.

In the next practical tip, we will show you how to check individual files online for viruses.