Microsoft makes emergency security fix

Microsoft has released an urgent update to stop hackers taking control of computers with a single email.

The unusual bug, in Microsoft anti-malware software such as Windows Defender, could be exploited without the recipient even opening the message, BBC News reports.

Researchers working for Google's Project Zero cyber-security outfit discovered the flaw at the weekend.

The fix has been specially pushed out hours before the software giant's weekly Tuesday security update.

Hackers could exploit the flaw simply by sending an infected email, instant message or getting the user to click on a web browser link.

Windows 8, 8.1, 10 and Windows Server operating systems are affected by the bug.

Anti-virus software such as Windows Defender would merely have to scan the malicious content for the exploit to be triggered.

This can be set up to occur almost instantly - "real-time protection" - or when scheduled scans are made.

"Anti-virus normally tries to intercept these things before you get to them," said cyber-security expert Graham Cluley.

He added it was "tremendous" that Microsoft had released the patch so quickly.