Win32/Virut.NBK is a malicious program that typically sneaks into a system (usually XP or Vista) by altering file names in the registry and installing various malware onto the infected PC. Once active, Win32/Virut.NBK will activate corrupt .exe and .dll files and download further malware threats onto your system. Usually you will find that Win32/Virut.NBK is spread due to pornographic web sites, infected email attachments or through suspicious file-sharing and shareware downloads.