The utility, released by Alex Ionescu and yanked an hour later after the kernel developer realized that the ATI driver flaw was not yet patched, provided an easy way to load unsigned drivers onto Vista — effectively defeating the new anti-rootkit/anti-DRM mechanism built into Microsoft's newest operating system. Ionescu confirmed his tool was exploiting a vulnerability in an ATI driver — atidsmxx.sys, version 3.0.502.0 — to patch the kernel to turn off certain checks for signed drivers. This meant that a malicious rootkit author could essentially piggyback on ATI's legitimately signed driver to tamper with the Vista kernel."
Flaw in ATI driver exposes Windows Vista kernel
Posted on Friday, Aug 10 2007 @ 15:12 CEST by Thomas De Maesschalck