Software giant Microsoft said the Duqu virus exploits a previously unknown hole in Windows. Security experts say it could be the next big cyber threat and Microsoft said that it will release a security update pretty smartish.

Duqu first appeared in October when security software maker Symantec found a mysterious computer virus that contained code similar to Stuxnet. It appears to have been developed by sophisticated hackers to help lay the groundwork for attacks on critical infrastructure such as power plants, oil refineries and pipelines.

Symantec researchers believe hackers sent the virus to targeted victims via emails with tainted Microsoft Word documents attached. Symantec's Kevin Haley told Reuters that some of the source code used in Duqu was also used in Stuxnet, a cyber weapon believed to have crippled centrifuges that Iran uses to enrich uranium.

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