Riihi virus was found in Finland in the beginning of December 1993. It's one of the smallest known functioning memory-resident viruses.
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.
When an infected program is first executed, Riihi becomes memory resident, and infects COM files as they are executed. Riihi does not decrease available DOS memory, and it does not show up in memory maps.
When the virus is resident, it will check every executed program. If the file extension is COM, and the program does not start with the 'M' letter, the virus infects it. The 'M' check is done in order not to infect EXE files that have been renamed to COM.
Infected programs grow by 132 bytes. The virus does not do anything except spread, and it does not contain any texts.
The exact origin of Riihi is not known, but it is suspected to be written in Finland - it caused several large-scale infections in Finland during December 1993 and January 1994.