Word security flaw investigated by Microsoft

Microsoft is investigating a security flaw in Word.

It says the vulnerability could allow malicious parties to steal files by bugging a document with a hidden code.

The firm is exploring how to fix the problem and whether to extend the repair to an older version of the software still used by millions.

The attack begins when a bugged document goes out, usually with a request to be revised and returned to the sender.

When the document is changed and sent back, the targeted file accompanies it.

The flaw would most likely occur in the workplace, where Word is the most prominent word processing program.

Potential targets for theft are sensitive legal contracts, payroll records or emails, either from a hard drive or computer network, depending on the victim's access to files.

Microsoft said in a statement: "The issue appears to affect all versions of Microsoft Word. When the investigation is completed, we will take the action that best serves Microsoft's customers."

However it appears that an old incarnation - Word 97 - is most susceptible. Microsoft said it is its policy to no longer repair Word 97, but said the company is still exploring the issue.

A research firm reported in May that about 32% of offices have copies of Word 97 running.