Threat Description



Category: Malware
Platform: W32
Aliases: nul, prn, lpt1, clock$


This is not a virus. Actually, the typical support query goes like this:

Question: I found a file called "nul" in my root directory. I can not access or delete it. Later I found it existed in each and every directory! This has to be a virus!

Answer: How did you find it? With which program?

Try locating in a same manner files with names such as "lpt1", "prn", "com1", "clock$" and you will see that they too exist in every directory and can not be accessed or deleted. This is normal and is a feature of DOS.

These are virtual names for system devices: prn for printer, nul for null port, clock$ for CMOS memory etc. Ignore them.


Automatic action

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

More scanning & removal options

More information on scanning or removal options is available in the documentation for your F-Secure security product on the Downloads section of our Home - Global site.

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

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Description Details: Mikko Hypponen, F-Secure


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