The TDSS botnet, now in its 4th generation, is seriously sophisticated malware, which is why we've spent so much time writing about it: the revision of the paper The Evolution of TDL: Conquering x64 that will be up on the white papers page shortly runs to 54 pages and includes some highly technical analysis, including the detail on

Recently … our TDL tracker picked up a brand new plugin for TDL4 kad.dll (Win32/Olmarik.AVA) which we haven’t seen earlier … we discovered that it implements a particularly interesting network communication protocol …