So how long has Sony known about the rootkit problem?

Curiouser and curiouser. According to Business Week, Sony were warned about the problem with their DRM system a full month before Mark Russinovich posted the news on his Blog — and did nothing. Excerpt:

Sony BMG is in a catfight with a well-known computer-security outfit that became aware of the software problem on Sept. 30 and notified the music company on Oct. 4 — nearly a month before the issue blew up. F-Secure, a Finland-based antivirus company that prides itself on being the first to spot new malware outbreaks, says Sony BMG didn’t understand the software it was introducing to people’s computers and was slow to react.

“If [Sony] had woken up and smelled the coffee when we told them there was a problem, they could have avoided this trouble,” says Mikko H. Hypponen, F-Secure’s director of antivirus research.