Insecurity outfit Sophos has warned that computer users should patch recently discovered Windows vulnerability as proof-of-concept code surfaces.

The Microsoft vulnerability, known as MS12-020 or the RDP flaw, was revealed this week. And now some Chinese websites have been showing some of proof-of-concept code that tries to exploit the hole.

The critical vulnerability could be exploited to spread a worm automatically between computers.  Earlier this week, Microsoft warned that it expected malicious hackers to exploit the flaw within 30 days, and Microsoft and Sophos are urging users to patch their copies of Windows as soon as possible.

Graham Cluley, senior technology consultant at Sophos said that the hackers worked quickly on this particular vulnerability and we've already seen attempts to exploit the flaw which exists in a part of Windows called the Remote Desktop Protocol (RDP).

Affected Windows computers will 'blue screen', but he wouldn't be surprised if whoever is writing this code tries to develop the attack further to produce a fast spreading internet worm, Cluely said.

Windows users should consider themselves on high alert and harden their defences by patching their PCs as soon as possible, before we see this worm turn even more malicious, he added.