The security flaw was first flagged up in May 2013 by a Google researcher.
Microsoft confirmed that some computers were being hacked by exploiting a bug in the Windows operating system.
The issue was first flagged up in May 2013 by a Google researcher, who was targeted for exposing the security flaw without initially informing the US-based software firm.
According to the software firm, the hackers had launched ‘targeted attacks’, which are usually launched against corporate or government targets with snooping as the intention.
Google security engineer Tavis Ormandy’s revelation in May 2013 turned out to be controversial as he published technical information on the Web that described the flaw in Windows OS, which was believed to trigger malicious hackers to launch attack, Reuters reported.
Ormandy also drew attention when he said that Microsoft’s security division was complex to work with.
In June 2013, Microsoft launched the preview version of Windows 8.1, an update of the Windows OS, which incorporates new developer tools and offers increased support.