This is a family of stealth multipartite fast infecting viruses originating from Australia. There are at least five variants, sizes ranging from 2 to 3 kB.
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.
One of the variants generates an endless loop to the partition table, making PC crash when it tries to boot from a clean floppy which has MS-DOS v4.0 - 7.0. To overcome this, use PC-DOS 7.0, MS-DOS 3.3x or a non-DOS boot floppy. Contact F-Secure anti-virus support for further instructions.
Note: Rainbow is also an alias for the WordMacro/Colors virus.