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Ipswitch IMail IMAP List Command DoS Vulnerability



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:



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.


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.


iDEFENSE has confirmed the existence of this vulnerability in Ipswitch
IMail 8.2.


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.


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


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



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.


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


Sebastian Apelt is credited with discovering this vulnerability.

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Copyright © 2005 Verisign, 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
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