Sony delivers rootkits with their digital rights management software

Last week when I was testing the latest version of RootkitRevealer (RKR) I ran a scan on one of my systems and was shocked to see evidence of a rootkit. Rootkits are cloaking technologies that hide files, Registry keys, and other system objects from diagnostic and security software, and they are usually employed by malware attempting to keep their implementation hidden.

I studied the driver's initialization function, confirmed that it patches several functions via the system call table and saw that its cloaking code hides any file, directory, Registry key or process whose name begins with '$sys$". To verify that I made a copy of Notepad.exe named $sys$notepad.exe and it disappeared from view. Besides being indiscriminate about the objects it cloaks, other parts of the Aries code show a lack of sophistication on the part of the programmer. It's never safe to unload a driver that patches the system call table since some thread might be just about to execute the first instruction of a hooked function when the driver unloads; if that happens the thread will jump into invalid memory. There's no way for a driver to protect against this occurrence, but the Aries driver supports unloading and tries to keep track of whether any threads are executing its code. The programmer failed to consider the race condition I've described.