There is no virus by this name. However, we sometimes get queries about this, since Microsoft Office's 'Fast Find' feature creates hidden files named like this to root directory: __OFIDX.FFA, __OFIDX.FFL, __OFIDX0.FFX. This is harmless.
Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.
Find the latest advice in our Community Knowledge Base.
See the manual for your F-Secure product on the Help Center.
Submit a file or URL for further analysis.