Most computer users are all too aware of the threat of viruses and worms infecting their machines, but according to security research firm BitDefender different types of malware may now be infecting each other to create a new breed of security risk. Dubbed "Frankenmalware," the hybrids are created when a virus infects a machine that has already been compromised by a worm. The virus attaches itself to executable files on the host system — including the worm — and when the latter spreads it carries the virus along with it. BitDefender claims it analyzed a sample of 10 million pieces of malware and discovered 40,000 different examples of the new breed. Code from the Virtob virus, for example, was found inside both the OnlineGames and Mydoom worms.

While the notion is frightening, it's important to keep the threat in perspective. Symantec product manager John Harrison told MSNBC that his company has seen no examples of this kind of malware mash-up, and it's impossible to know if the discovered examples were the true result of malware breeding in the wild, or simply the work of malicious programmers combining previous efforts into new creations. Fortunately, BitDefender notes that the multiple signature code elements within a hybrid may make it even easier for anti-virus software to detect the mutant strains and remove them from your system.