Microsoft: Messenger flaw can expose user data

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By Sam Costello

(IDG) -- Microsoft has confirmed that its instant messaging programs -- MSN Messenger and the Windows Messenger, included with the company's Windows XP operating system -- can allow users' names and e-mail addresses, as well as those of their chat buddies, to be viewed.

The issue was first mentioned in an alert posted to the Bugtraq security e-mail list on February 2.

The flaw, which was discovered by Richard Anthony Burton, allows a Javascript placed on a Web page visited by MSN Messenger users to obtain a user's display name for the chat program, as well as the names of all their contacts in the program, he wrote. This could allow many people's real names to be harvested by malicious Web sites, he said. If no display name is set in the program, the Javascript will obtain the user's e-mail address instead, according to Burton.

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Some Web sites owned by Microsoft are able to access the e-mail addresses of users and all their contacts, Burton wrote. The technique used by these sites to monitor user visits could also be used by other Web sites, if users downloaded software that changed their computer settings slightly to allow the monitoring, he wrote. Such a change might be made without warning the user, he added.

In Burton's test, the bug affects MSN Messenger 4.60073 on Windows 2000 using Internet Explorer 6 and the same versions of Windows Messenger and Internet Explorer on Windows XP.

The flaw, which a Microsoft spokeswoman acknowledged Friday to be present, exists as part of a feature designed to allow Messenger users to be notified when they've received new e-mail in their Hotmail accounts, and to see if the person who has sent an e-mail to those accounts is online with Messenger.

Although Microsoft is treating the flaw as low-risk, it will release a new version of the Messenger products that addresses the issue early this week, the spokeswoman said. Users will be notified that a new version is available and will be prompted to download it, the spokeswoman said.

Concerned users can go to the MSN Messenger support Web site for information about the issue and steps they can take to protect themselves, the spokeswoman said.

That page is located at http://messenger.msn.com/support/status.asp.