A proof-of-concept tool put together by a ReactOS kernel developer Alex Ionescu has unmasked a serious vulnerability in AMD’s graphics drivers for Windows Vista. As ZDNet reports, the security hole allows the Vista kernel to be patched to turn off “certain checks for signed drivers.” Through this vulnerability, a malicious programmer could develop software capable of bypassing the mandatory driver signing mechanism in Windows Vista x64 in order to load a rootkit—a tool designed to conceal the operation of other malicious software—onto the operating system.
Ionescu says he released his “Purple Pill” proof of concept without knowing that the flaw in AMD’s graphics drivers had not yet been patched. Roughly an hour and 20 minutes after realizing his mistake, Ionescu pulled the proof of concept. However, the file had already been downloaded 39 times. When asked about the security hole, a Microsoft spokesman told ZDNet, “Microsoft is in contact with ATI to help address this issue and once fixed we will assist in getting it to our customers.”