It has been criticized for not telling Microsoft the first time it has been disclosed.

July 10, Microsoft said recently that hackers attacked some computers by using a Windows vulnerability released by a Google researcher two months ago, Reuters reported. The researchers have been blamed for disclosing vulnerabilities without first informing Microsoft.

Microsoft did not disclose the attack in detail. It said in a Tuesday announcement that hackers had launched "targeted cyber attacks". The term "targeted cyber attack" is often used by security experts to refer to an attack directed against an enterprise or government target for spying and sabotage.

Tavis Ormandy, Google's security engineer, Tavis Omandi The May disclosure was controversial, as technical information he posted on the web described Windows system vulnerabilities that some experts believe could help malicious hackers launch attacks before Microsoft releases repair files.

A Microsoft spokeswoman declined to respond when asked if it was thought that Omandi's disclosure of the vulnerability had led to cyber attacks.

Omandi also received attention for posting a barrage of attacks on Microsoft, when he said it was difficult to work with Microsoft's security services and suggested other researchers use pseudonyms and anonymous emails when communicating with the software company.

Omandi is not yet available to comment. A Google spokeswoman declined to respond, saying that Omandi's Windows project was a personal project, unrelated to his work in the company.