Microsoft warns users of another 'critical' flaw

Consumers using Microsoft Office software have been warned theyare at risk of having their computers taken over by hackers unlessthey apply a software patch to correct the problem.

The world's largest software maker said a "critical" flaw in itsVisual Basic for Applications software, used to develop applicationsfor Windows and Office, could enable a malicious programmer tocreate documents that would launch attacks on unsuspecting users.

The warning, which comes just a week after the Sobig viruswreaked havoc on global computer systems, will focus furtherattention on Microsoft's vulnerability to attacks by hackers andcomputer viruses.

Computer systems in universities and several companies in theRepublic using Microsoft's operating system software have crashed inrecent weeks because of a succession of virus attacks.

Microsoft has vowed to improve the security and reliability ofits software, which has been hit by several high-profile flaws thisyear. The Slammer worm caused serious delays in internet traffic inJanuary, while the Blaster worm and its variants crippled hundredsof thousands of computers in August.

Computer experts said yesterday the new weakness disclosed byMicrosoft could lead to the creation of new viruses unless usersdownloaded a new software patch made available by Microsoft.

Microsoft urged users in a security bulletin (http://www.microsoft.com/security/) to apply the software fix.

At risk were recent versions of Microsoft's Access, Excel,PowerPoint, Publisher, Visio, Word and Works applications, which arepart of the Office family of software used in a range of tasks suchas creating databases, documents, spreadsheets and presentations aswell as publishing documents and Web pages.

Microsoft Office is one of the most popular desktop softwaresuites used by consumers and business.

Some applications from Microsoft's Great Plains business softwaredivision were also affected, Microsoft said yesterday.

A user could trigger an attack by opening a document for any ofthose programs that contain Visual Basic components, the companysaid.

However, experts said that any virus that exploited the VisualBasic flaw was unlikely to cause major damage.

"There are a number of factors that minimise the risk in thiscase," said Mr Oliver Friedrichs, a senior manager at computersecurity and services provider Symantec.

"You need to open a document that someone sends you to, wherewith Blaster you simply had to be on the internet to be infected,"he said.

--(Additional reporting: Reuters)