Kthulhu is a direct action file virus which infects COM files in the current diretory every time an infected file is executed. Virus doesn't infect smaller files than 600 bytes or bigger than 61000 bytes. Virus searches for signature FA8Bh at file offset 9 or 13 (which may mean that there may be 2 different versions of the virus).
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.
During infection the filename is changed to KTHULHU, if an abnormal error occurs in the process of infecting a file, the original name is not restored and no other tidying up is done. Instead a line is written to the screen which just says '!'. Normally file attributes are restored and the file date/time preserved.
After infection virus checks if the month is May. If it notices that the month is May, it displays different text messages on the screen depending on the date. Before May 20th, it says 'IT is coming.' and after May 20th it tells 'It has gone.'. If the system date is exactly May 20th, it says 'Today is my birthday.' and beeps. Then, when user touches keyboard for the next time, the virus does a warm reboot.