Ipswitch IMail IMAP List Command DoS Vulnerability

iDEFENSE Security Advisory 12.06.05
www.idefense.com/application/poi/display?id=347&type=vulnerabilities
December 6, 2005

I. BACKGROUND

Ipswitch Imail Server is an email server that is part of the IpSwitch
Collaboration suit. Imail Supports POP3, SMTP, IMAP and web based email
access. More Information can be located on the vendor’s site at:

http://www.ipswitch.com/Products/collaboration/index.html

II. DESCRIPTION

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

The problem specifically exists in handling long arguments to the LIST
command. When a LIST command of approximately 8000 bytes is supplied,
internal string parsing routines can be manipulated in such a way as to
reference non-allocated sections of memory. This parsing error results
in an unhandled access violation, forcing the daemon to exit.

III. ANALYSIS

Exploitation allows remote attackers to crash vulnerable IMAP servers
and thereby prevent legitimate usage. The LIST 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 Ipswitch
IMail 8.2.

V. WORKAROUND

As this vulnerability is exploited after authentication occurs, ensuring
that only trusted users have accounts can mitigate the risk somewhat. 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

Ipswitch Collaboration Suite 2.02 has been released to address this
issue and is available for download at:

http://www.ipswitch.com/support/ics/updates/ics202.asp

IMail Server 8.22 Patch has been released to address this issue and is
available for download at:

http://www.ipswitch.com/support/imail/releases/imail_professional/im822.asp

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-2923 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

09/08/2005 Initial vendor notification
09/13/2005 Initial vendor response
10/06/2005 Coordinated public disclosure

IX. CREDIT

Sebastian Apelt is credited with discovering this vulnerability.

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X. LEGAL NOTICES

Copyright © 2005 iDEFENSE, Inc.

Permission is granted for the redistribution of this alert
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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.