May 09, 2002, 9:30 AM — A security hole deemed "critical" by Microsoft Corp. could allow an attacker to run code of their choice on a vulnerable PC by exploiting a problem in Microsoft's MSN Chat, MSN Messenger and Exchange Instant Messenger products, Microsoft said in a security alert Wednesday. The company has patched the vulnerability.
The vulnerability comes in an ActiveX control that allows users of MSN Chat, Messenger and Exchange Instant Messenger to group together in a single "space" to chat in real time, Microsoft said. A buffer overflow in the component could allow an attacker to assault the flaw and run any code against vulnerable machines, Microsoft said. An attacker could also exploit the vulnerability using a malicious Web site or through e-mail formatted in HTML (Hypertext Markup Language), the Redmond, Washington, company said.
The ActiveX component that allows the chat feature is included with MSN Messenger 4.5 and higher and Exchange Instant Messenger, Microsoft said. MSN Chat users and Windows XP users, however, would only be vulnerable to the bug if they had downloaded and installed the chat component separately, Microsoft said.
E-mail users are protected if they have downloaded the Outlook E-Mail Security Update or are running Outlook 2002 or Outlook Express, the company said.
More information about the vulnerability, and a patch to repair it, are available at http://www.microsoft.com/technet/security/bulletin/ms02-022.asp.
Microsoft's chat problem comes three days after the announcement of a security hole in rival America Online Inc.'s Instant Messenger application that could have allowed attackers to run programs of their choice. That flaw has since been patched by AOL.
