Category :


Type :


Aliases :



One unusual "feature" of this virus is that it will search the disk for the string "Microsoft" and change it into "MACROSOFT". The virus will not infect programs if the environment contains SYSLOCK=@.


Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    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.

    Note: You need administrative rights to change the settings.

Technical Details


Two minor variants, which will transform the string "Microsoft" into "MACHOSOFT". One is very close to the original SysLock virus, with only one byte different, but the other has been modified somewhat.


Activates in December and plays "Oh, Tannenbaum".


The last variant is 2232 bytes long and known as "Cookie", because it may display the message

I want a COOKIE!