The SP2 measure, known as Data Execution Protection, is intended to prevent would-be attackers from inserting rogue code into a PC's memory and tricking Windows into running the program. However, in a paper published Friday, Moscow-based Positive Technologies said two minor mistakes in the implementation of the technology allow a knowledgeable programmer to sidestep the protection.
The company notified Microsoft of the problem Dec. 22, but it apparently decided not to wait for the software giant to patch the flaws.
Neither Microsoft nor Positive Technologies immediately responded to requests for comment Friday.
After several delays, Microsoft began, at which time company Chairman Bill Gates called the update "a significant step in delivering on our goal to help customers make their PCs better isolated and more resilient in the face of increasingly sophisticated attacks."