Security Bulletin MS02-058: Unchecked Buffer in Outlook Express S/MIME Parsing Could Enable System Compromise (Q328676)

2002-10-11T00:00:00
ID SECURITYVULNS:DOC:3621
Type securityvulns
Reporter Securityvulns
Modified 2002-10-11T00:00:00

Description


Title: Unchecked Buffer in Outlook Express S/MIME Parsing Could Enable System Compromise (Q328676) Date: 10 October 2002 Software: Outlook Express Impact: Run code of attacker's choice. Max Risk: Critical Bulletin: MS02-058

Microsoft encourages customers to review the Security Bulletin at: http://www.microsoft.com/technet/security/bulletin/MS02-058.asp.


Issue:

To allow for verification of the authenticity of mail messages, Microsoft Outlook Express supports digital signing of messages through S/MIME. A buffer overrun vulnerability lies in the code that generates the warning message when a particular error condition associated with digital signatures occurs.

By creating a digitally signed email and editing it to introduce specific data, then sending it to another user, an attacker could cause either of two effects to occur if the recipient opened or previewed it. In the less serious case, the attacker could cause the mail client to fail. If this happened, the recipient could resume normal operation by restarting the mail client and deleting the offending mail. In the more serious case, the attacker could cause the mail client to run code of their choice on the user's machine. Such code could take any desired action, limited only by the permissions of the recipient on the machine.

This vulnerability could only affect messages that are signed using S/MIME and sent to an Outlook Express user. Users of Microsoft Outlook products are not affected by this vulnerability.

Mitigating Factors:

  • Microsoft Outlook is not affected by this vulnerability.
  • Outlook Express runs in the context of the user. Exploiting this vulnerability would in the worst case scenario allow an attacker to run arbitrary code in the context of the users' privileges only. Any restrictions on the users' account would apply to the attackers code.

Risk Rating:

  • Internet systems: Low
  • Intranet systems: Low
  • Client systems: Critical

Patch Availability:

  • A patch is available to fix this vulnerability. Please read the Security Bulletin at http://www.microsoft.com/technet/security/bulletin/ms02-058.asp for information on obtaining this patch.

Acknowledgment:

  • Noam Rathaus of Beyond Security Ltd. (http://www.beyondsecurity.com)

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.