Rootkits "Serious" Security Problem

The hacker equivalent of a cloak of invisibility may cause serious problems for users and anti-virus vendors, a security expert said Thursday.

Rootkits, which hark back to Unix, are tools used by hackers to cover their tracks. Rootkits -- even the name comes from Unix, for it refers to the term for the OS's super-user, the root user -- can hide the existence of other malware on a computer by modifying file data, Windows registry keys, or active processes, all of which are used by malicious code detection software to spot worms, viruses, and spyware that's been installed on a PC.