One big mystery about the Sony DRM fiasco is why were the anti-virus companies so slow to deal with the Sony rootkit? Now we know. The answer: they were afraid of

violating the Digital Millennium Copyright Act, according to security expert Dan Kaminsky. He says creating new software to remove DRM software is a violation of the DMCA, forcing antivirus companies to create patches that eliminate the software’s dangerous behavior, but do not remove it.