Microsoft Office users attacked by cybercriminals

* Microsoft Office attacked by hackers

* Cybercriminals can take control of vulnerable PCs

* Microsoft has yet to issue patch to protect users

By Jim Finkle

BOSTON, July 14 (Reuters) - Microsoft Corp (MSFT.O: Quote, Profile, Research) warned that cybercriminals have attacked users of its Office software for Windows PCs, exploiting a programming flaw that the software giant has yet to repair.

The world's largest software maker issued the warning on Tuesday as it released patches to address nine other security holes in its software.

"Despite today's fixes, Windows users continue to be under attack. Microsoft is taking two steps forward, while attackers are putting it one step back," said Dave Marcus, McAfee Inc's (MFE.N: Quote, Profile, Research) Avert Labs director of security research.

Hackers booby-trap websites with malicious code that loads onto computers running the vulnerable Office software. Infected PCs are commandeered into a botnet, a network of hijacked computers. They are used for identity theft, spamming and other cybercrimes.

Microsoft did not say how many machines were attacked. It estimates that some 500 million people use its Office suite, which includes Word, Excel and PowerPoint software.