Microsoft patches security hole in Office 2000

The Microsoft Office Assistant, the talking paper clip that Microsoft has cited as an example of its software innovation during the US Government's antitrust investigation, has been found to include a security hole that allows attackers to take over a user's computer.

Microsoft has released a patch it says eliminates the vulnerability in Office 2000 and component applications such as Word 2000, Excel 2000 and PowerPoint 2000.

The flaw was revealed by the security firm @Stake L0pht Research Labs, which said the problem originated with an ActiveX control named Microsoft Office UA Control that shipped with Microsoft Office 2000. According to Microsoft, the Office 2000 UA Control, which is installed by default, is used by the "Show Me" function in Office Help to allow Office functions to be scripted.

While the control is categorised as being "safe for scripting," @Stake's analysis of the control's interface showed that it could script almost any action into Office 2000 - including the lowering of macro security settings. The @Stake advisory noted that the script can be delivered from any HTML page that is viewed in an application with active scripting enabled, including default configurations of Internet Explorer and the Outlook e-mail client.

"With the vulnerability you could completely take over someone's machines, steal the whole cookie file, steal or modify any file or plant remote-control software," said @Stake security researcher Weld Pond, who noted that the hole was potentially much more damaging than the recently discovered Internet Explorer cookie vulnerability.

Microsoft acknowledged in its Security Bulletin that the Active X control that shipped with Office 2000 is incorrectly marked as "safe for scripting". It confirmed that a malicious Web-site operator could use the flaw to carry out Office functions on the machine of a user who visited the site.

The @Stake researcher who discovered the hole, who goes by the name DilDog, was thanked by Microsoft in a security bulletin that acknowledged the flaw.

DilDog also noted in the advisory that while the control was labelled "safe for scripting" and assessable remotely, it was undocumented by Microsoft.