Microsoft patch can disable Outlook Web Access

IDG News Service - A patch released last week to fix a flaw in the Outlook Web Access module of Microsoft Corp.'s Exchange 5.5 Server can render the Web-based e-mail system useless, administrators complained, prompting Microsoft to update and re-release its security bulletin.
"Unexpected consequences" may result due to file dependency issues if the Outlook Web Access server that the patch is applied to doesn't have Internet Explorer Version 5.0 or greater installed, Microsoft said in the revised version of bulletin MS01-057, issued late Friday.
Installing the patch on servers with an older version of Internet Explorer had various results, according to postings in a forum for Exchange administrators on Microsoft's TechNet Web site. There are reports of disabled systems that show only message headers, not the body, as well as general installation problems.
Exchange administrators could be getting used to having to deal with several versions of security bulletins and patches before their systems are patched and running again. Earlier this year, it took Microsoft three patches to plug a similar Outlook Web Access hole in Exchange 2000 (see story). Exchange 5.5 was also affected, but that patch worked on the first go.
The original bulletin, released late Thursday (see story), didn't list any caveats. The updated bulletin lists the Internet Explorer version requirement and recommends that users upgrade to Version 5.5 with Service Pack 2 or Internet Explorer 6.0. Hotfix support is available only for these latest versions of Internet Explorer, Microsoft said.
The patch is to fix a flaw in the way Outlook Web Access handles in-line script in HTML e-mail messages. An attacker can hijack a user's mailbox when his message with malicious code is opened using Internet Explorer and Outlook Web Access, according to Microsoft.
Related stories:

• Flaw detected in Windows Media Player, Nov. 20, 2001


• Microsoft issues patch for hole in Internet Explorer, Nov. 15, 2001


• Microsoft offers two new security tools, Aug. 16, 2001

Reprinted with permission from

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