If this is true, it seems reasonable to start boycotting Sony. (appearing all over the web ... I don't buy Sony CDs these days and don't use Windows, so I can't verify)
At that point I knew conclusively that the rootkit and its associated files were related to the First 4 Internet DRM software Sony ships on its CDs. Not happy having underhanded and sloppily written software on my system I looked for a way to uninstall it. However, I didn’t find any reference to it in the Control Panel’s Add or Remove Programs list, nor did I find any uninstall utility or directions on the CD or on First 4 Internet’s site. I checked the EULA and saw no mention of the fact that I was agreeing to have software put on my system that I couldn't uninstall. Now I was mad.
I deleted the driver files and their Registry keys, stopped the $sys$DRMServer service and deleted its image, and rebooted. As I was deleting the driver Registry keys under HKLM\System\CurrentControlSet\Services I noted that they were either configured as boot-start drivers or members of groups listed by name in the HKLM\System\CurrentControlSet\SafeBoot subkeys, which means that they load even in Safe Mode, making system recovery extremely difficult if any of them have a bug that prevents the system from booting.
When I logged I discovered that the CD drive was missing from Explorer. Deleting the drivers had disabled the CDs. Now I was really mad. Windows supports device “filtering”, which allows a driver to insert itself below or above another one so that it can see and modify the I/O requests targeted at the one it wants to filter. I know from my past work with device driver filter drivers that if you delete a filter driver’s image, Windows fails to start the target driver. I opened Device Manager, displayed the properties for my CD-ROM device, and saw one of the cloaked drivers, Crater.sys (another ironic name, since it had ‘cratered’ my CD), registered as a lower filter:
Unfortunately, although you can view the names of registered filter drivers in the “Upper filters” and “Lower filters” entries of a device’s Details tab in Device Manager, there’s no administrative interface for deleting filters. Filter registrations are stored in the Registry under HKLM\System\CurrentControlSet\Enum so I opened Regedit and searched for $sys$ in that key. I found the entry configuring the CD’s lower filter:
I deleted the entry, but got an access-denied error. Those keys have security permissions that only allow the Local System account to modify them, so I relaunched Regedit in the Local System account using PsExec: psexec –s –i –d regedit.exe. I retried the delete, succeeded, and searched for $sys$ again. Next I found an entry configuring another one of the drivers, Cor.sys (internally named Corvus), as an upper filter for the IDE channel device and also deleted it. I rebooted and my CD was back.
The entire experience was frustrating and irritating. Not only had Sony put software on my system that uses techniques commonly used by malware to mask its presence, the software is poorly written and provides no means for uninstall. Worse, most users that stumble across the cloaked files with a RKR scan will cripple their computer if they attempt the obvious step of deleting the cloaked files.
While I believe in the media industry’s right to use copy protection mechanisms to prevent illegal copying, I don’t think that we’ve found the right balance of fair use and copy protection, yet. This is a clear case of Sony taking DRM too far.