Microsoft plans to release a security update for Office 2003 to curb the onslaught of zero-day attacks against Word, Excel and PowerPoint.  

The Microsoft Office Isolated Conversion Environment (Moice) plug-in screens Office 2003 documents for security irregularities, and converts them to Microsoft's new Open XML document format.

Moice opens new documents in a restricted environment, commonly referred to as a sandbox, that prevents an infected file from attacking the operating system, applications and data.

Once the document has been scanned, scrubbed of any potential security irregularities and converted to Open XML, it opens as normal in Office 2003.

Microsoft planned to release Moice on 8 May as part of its monthly Patch Tuesday security release cycle. However, the company said that delays in the non-English versions would affect the global release.

A Microsoft spokesperson originally told vnunet.com that the delay could be 'a matter of weeks.' The company has since backtracked on that assesment, stating that there is no definite time frame for the release.

Microsoft Office technical product manager Josh Edwards told vnunet.com in an interview that the new security technology will cause a "noticeable" delay when opening a new document.

Online criminals have launched a barrage of attacks in recent months targeting so-called zero-day vulnerabilities in Excel, Word and PowerPoint.

The attacks targeted key staff members at corporations with a document in an email attachment.

Researchers have traced most of the attacks to China and suspect that the criminals were out to steal customer data and other confidential information.  

Tim Hickernell, a senior analyst at Infotech Research Group, expects that the new plug-in will find most use in specific security-conscious business segments rather than consumers. 

Government organisations, financial institutions and software firms with large amounts of sensitive or valuable information are most likely to adopt Moice, he said, as the the tool will provide a way of preventing old infected files from compromising system security.