A method of bypassing security features in Windows XP Service Pack 2 (SP2) isn't actually a security threat, Microsoft has claimed.

The software giant downplayed the seriousness of a security hole publicised on Monday by Russian security firm Positive Technologies. Positive published a patch for the hole, which could allow an attacker to bypass SP2's Data Execution Protection (DEP), after waiting for more than a month for a Microsoft response, it said.

But Microsoft has now said that while it is investigating Positive's findings, an initial examination showed the bypass was "not a security vulnerability".

"An attacker cannot use this method by itself to attempt to run malicious code on a user's system. There is no attack that utilises this, and customers are not at risk from the situation," Microsoft said in a statement.

DEP is a set of hardware and software technologies that perform additional checks on memory to help prevent malicious code from running on a system. According to Positive Technologies chief technology officer Yury Maximov, Positive informed the software maker on 22 December about a problem with DEP and was told to wait for a response from the company.

A month later, the company decided to release its own patch, partly because Maximov understood that hacker groups were already working on ways to exploit the holes in DEP to insert rogue code into a PC's memory.

Microsoft said DEP and heap overflow protection are not really compromised by Positive's findings - they still do their job. "These features effectively address the exploits that they were designed to prevent and make it more difficult for an attacker to run malicious software on the computer as the result of a buffer overrun," the company said. Microsoft added that the features are not designed to protect against all malicious code, just buffer overruns.

The company said it may patch the bypass method in a future update or service pack.

In the meantime, Positive has developed a temporary security measure, which it made available on Friday as a free utility called PTmsHORP. Some industry analysts have advised against using third-party patches however.