Although Mac systems are not affected by the Windows-specific Sony rootkit threat, there may be Mac-specific DRM on some recent Sony CDs.

Larry Loeb at SecurityITHub provides the details:

Imogen Heap's new CD, "Speak for Yourself," on RCA Victor (a BMG subsidiary), has an extra partition for "enhanced" content. Along with Windows files, there is a Mac file present called "Start.app."

Unlike the Windows version, the Mac malware is not hidden, and does not install itself automatically. You have to do it yourself.

When run, a EULA is first displayed (which does inform the user that software is going to be installed without saying exactly what that software will do).

The user then is prompted by the program for a user name and password. After that information is provided, the program seemingly quits. However, it actually installs two kernel extensions, PhoenixNub1.kext and PhoenixNub12.kext, in the OS X system files.

So. To infect your Mac, you must:
  1. Trust Sony.
  2. Be curious enough to install mystery software.
  3. Locate the Mac software on the audio CD.
  4. Manually start the installation process.
  5. Override security with a user name/password.

Don't be so smug. This could happen. (Well, before this week, it could have happened. After this week, even people who lack common sense won't make it past #1.)

Loeb says the offending files appear to be part of a DRM solution sold by SunnComm.

Link: Sony DRM Comes in Mac Flavor Too