Fantibag.B is a trojan that installs a packet filter for preventing of downloading the AV companies database updates and security patches. It is related to recent Bagle/Mitglieder trojans.
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 detection database 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 the trojan's file is executed, it copies itself in the Windows directory with the name 'firewall_anti.exe'. It installs the following registry key to ensure that it will be executed at system startup: [HKLM\Software\Microsoft\Windows\CurrentVersion\Run] "firewall_anti" = "%WinDir%\firewall_anti.exe" The trojan drops a DLL 'firewall_anti.dll' in the Windows direcory and injects this file in the address space of Internet Explorer.
When the dropped DLL is activated, it modifies the network interface with Microsoft RAS packet filtering API. It adds a filter that blocks access to following AV companies and other security related sites: