There are 11 new malicious programs in the Top Twenty, a new leader and its very unclear what the future may hold. Two classic viruses, Virutav and Virut.av, both pose a serious threat and are spreading rapidly. The most widespread adware program, BHO.cc, continues to move up and down the charts. Sohanad IM worms have disappeared from the rankings. The distribution of programs in Top Twenty by class is close to parity: 6 representatives of the VirWare class (Viruses and Worms), 9 TrojWare programs and 4 AdWare programs.”]
Source: https://securelist.com/online-scanner-top-twenty-for-november-2007/36181/