Access to the source code could allow hackers to exploit the operating system and attack machines running Windows. Microsoft has only shared its source code with close partners and carefully-chosen organisations, and threatened legal action in the event that any of is leaked.

Microsoft posted on its website the fallowing message: "It's illegal for third parties to post Microsoft source code, and we take such activity very seriously. We are currently investigating these postings, and are working with the appropriate law enforcement authorities.

"At this point, it does not appear that this is the result of any breach of Microsoft's corporate network or internal security. At this time, there is no known impact on customers. We will continue to monitor the situation."

Some technology analysts like Rob Enderle try to lower the signifiance of the incident. He told Associated Press: "It seems unlikely that this is going to create a material, significant security problem. It's more embarrassing than anything else, because it makes it look like Microsoft can't control its code."

Others say it was expected. "I don't understand why it hasn't happened sooner, because there are so many organisations out there that have access to the source code," Marc Maiffret, chief hacking officer for security of Californian firm eEye Digital Security.

Another Microsoft problem is the delay with which is releasing patches. Security researchers are both criticizing and empathizing with Microsoft for the 200 days the company needed to create its latest critical software patch.

The six-plus months is the longest the software giant has taken to release a fix since it started its Trustworthy Computing initiative, a companywide mandate to make security a top priority. Taking so long to fix a serious issue cast doubts on how much progress Microsoft has made in the two-year effort, said Marc Maiffret.

"If it really took them that long technically to make (and test) the fix, then they have other problems, ... That's not a way to run a software company."

This kind of problems do not exists with open source projects and more people and organizations consider switching from the Windows operating systems to Linux.