Microsoft officials stuck to their long-standing defense that Vista goes a long way toward mitigating many common PC security issues and that the company will continue to bring new security features to bear on the OS and future products. Microsoft said it is further investigating several specific product flaws cited in the Symantec report, including the ASLR problem.

"It is important to note that none of the security features in Windows Vista, either individually or collectively, are intended as a 'Silver Bullet' solution to the problem of computer security," said Russ Humphries, senior product manager, Windows Vista Security.

"We believe Microsoft has developed the right balance and made the right decisions when evaluating the tradeoffs between usability and security," Humphries said. "[Symantec's] report does not properly address the fact that many of the Window Vista security technologies have numerous options that allow for a user to make their own judgments as to their need for security balanced against usability."