Vulnerability Note VU#252146

Microsoft Outlook and Microsoft Exchange TNEF decoding buffer overflow

TNEF is a proprietary Microsoft format for encoding rich text email messages. Microsoft Outlook and Microsoft Exchange support the use of TNEF-encoded messages.

The problem

Microsoft Outlook and Microsoft Exchange do not properly validate TNEF MIME attachments, potentially allowing a buffer overflow to occur. The overflow occurs in in the process that decodes TNEF MIME attachments. A remote attacker may be able trigger the buffer overflow by sending a specially crafted TNEF MIME attachment to a vulnerable Outlook or Exchange installation.

Note that on user workstations, exploitation may require a user to open or preview a malicious mail message in Outlook. However, on Exchange servers, this vulnerability can be exploited without human interaction.

For more information, please see Microsoft Security Bulletin MS06-003.

II. Impact

Microsoft addresses this vulnerability with the updates listed in Microsoft Security Bulletin MS06-003.

Workarounds

Microsoft has listed several workarounds in Microsoft Security Bulletin MS06-003, including blocking attachments with the MIME type of application/ms-tnef.

Systems Affected

http://www.microsoft.com/technet/security/bulletin/ms06-003.mspx
http://support.microsoft.com/kb/224817
http://support.microsoft.com/kb/290809

Credit

This vulnerability was reported by Microsoft, who in turn credit John Heasman and Mark Litchfield of NGS Software.

This document was written by Will Dormann and Jeff Gennari.

Other Information

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