Microsoft Exchange Server 2000 IMAP Literal Processing DoS Vulnerability

iDefense Security Advisory 05.08.07
http://labs.idefense.com/intelligence/vulnerabilities/
May 08, 2007

I. BACKGROUND

Microsoft Exchange Server 2000 is a messaging product developed by
Microsoft, part of the Windows Server System line of server products.
More information about it can be found at the following URL.

http://www.microsoft.com/technet/prodtechnol/exchange/2000/default.mspx

II. DESCRIPTION

Remote exploitation of an integer overflow vulnerability in the IMAP
service of Microsoft Exchange 2000 could allow a remote attacker to
crash all running Exchange services and other services in the same
process.

The vulnerability specifically exists in code responsible for reading of
literals in the IMAP4 service. When the IMAP4 service encounters a
specially crafted literal, it fails to properly process it. An access
violation occurs causing an unhandled exception that terminates the
process.

III. ANALYSIS

Exploitation of this vulnerability allows an attacker to cause the
affected server to restart or potentially require data to be
reinstalled from backup.

As the Exchange server may run in the same process space as many other
servers, crashing the IMAP4 component will also cause the SMTP, POP3,
WWW and FTP services, if enabled, to exit. In order to exploit this
vulnerability, the attacker must have access to establish a TCP session
with the IMAP4 service.

IV. DETECTION

iDefense confirmed the existence of this vulnerability in Microsoft
Exchange
2000 with Service Pack 3.

V. WORKAROUND

iDefense is not currently aware of any effective workarounds for this
vulnerability. Consider applying network access controls on this
service.

VI. VENDOR RESPONSE

Microsoft has addressed this vulnerability within MS07-026. For more
information, consult their bulletin at the following URL.

http://www.microsoft.com/technet/security/Bulletin/MS07-026.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-0221 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org/), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

01/10/2007  Initial vendor notification
01/22/2007  Initial vendor response
05/08/2007  Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by Joxean Koret.

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X. LEGAL NOTICES

Copyright © 2007 iDefense, Inc.

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Disclaimer: The information in the advisory is believed to be accurate
at the time of publishing based on currently available information. Use
of the information constitutes acceptance for use in an AS IS condition.
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