Ufa is a direct action file virus which tries to infect several COM files every time when an infected program is executed.
It seems that the virus author has tried to make the virus to overwrite a random sector on the current drive with garbage, if the virus has been in the system for 30 days. However, the virus code contains a bug which usually prevents this.
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.
Virus searches candidate files to be infected in the current directory and then up to 9 directories along the search path. Virus attempts to infect a maximum of 10 files in each directory. Because this might take a long time, especially on slow computer, virus has a time limit for infection. When the limit has been reached, virus stops infecting files. Next time, when an infected program is executed, virus starts infecting files again. During the infection process, virus disables the Ctrl-Break key sequence.
If files match "*.COM", have the archive bit set and are not system or hidden files, they are checked for infectability. Files smaller than 512 bytes are not infected. The virus does not reinfect infected files. Virus can't preserve the file date, so all infected files has their date and time fields changed to the moment infection took place.
This virus seems to be written in BASIC or some similar high-level language.