Ipswitch IMail IMAP SELECT Command DoS Vulnerability

iDEFENSE Security Advisory 05.24.05
www.idefense.com/application/poi/display?id=241&type=vulnerabilities
May 24, 2005

I. BACKGROUND

Ipswitch IMail server is a Windows based messaging solution with a
customer base of over 53 million users. More information about the
application is available at:

    http://www.ipswitch.com/products/IMail_Server/index.html.

II. DESCRIPTION

Remote exploitation of a denial of service vulnerability in Ipswitch
Inc.'s Imail IMAP server allows attackers to crash the target service
thereby preventing legitimate usage.

The problem specifically exists in the handling of long arguments to the
SELECT command. When a string approximately 260 bytes in size is
supplied a stack-based buffer overflow occurs that results in an
unhandled access violation forcing the daemon to exit. The issue is not
believed to be further exploitable.

III. ANALYSIS

Successful exploitation allows remote to crash vulnerable IMAP servers
and thereby prevent legitimate usage. The SELECT command is only
available post authentication and therefore valid credentials are
required to exploit this vulnerability

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in the latest
version of Ipswitch IMAIL, version 8.13. Version 8.12 is also confirmed
as vulnerable. It is suspected that earlier versions are vulnerable as
well.

V. WORKAROUND

As this vulnerability is exploited after authentication occurs, ensuring

that only trusted users have accounts can mitigate the risk somwhat. As 
a more effective workaround, consider limiting access to the IMAP server

by filtering TCP port 143. If possible, consider disabling IMAP and 
forcing users to use POP3.

VI. VENDOR RESPONSE

The vendor has released the following patch to fix this vulnerability:

ftp://ftp.ipswitch.com/Ipswitch/Product_Support/IMail/imail82hf2.exe

The associated vendor advisory can be found at:

http://www.ipswitch.com/support/imail/releases/imail_professional/im82hf
2.html

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-1254 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

04/15/2005  Initial vendor notification
05/10/2005  Initial vendor response
05/24/2005  Coordinated public disclosure

IX. CREDIT

Sebastian Apelt is credited with this discovery.

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X. LEGAL NOTICES

Copyright (c) 2005 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
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part of this alert in any other medium other than electronically, please
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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.
There are no warranties with regard to this information. Neither the
author nor the publisher accepts any liability for any direct, indirect,
or consequential loss or damage arising from use of, or reliance on,
this information.