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Category:   Application (E-mail Server)  >   IMail Server Vendors:   Ipswitch
Ipswitch IMail Server IMAP LIST Command Bug Lets Remote Authenticated Users Deny Service
SecurityTracker Alert ID:  1015318
SecurityTracker URL:
CVE Reference:   CVE-2005-2923   (Links to External Site)
Date:  Dec 7 2005
Impact:   Denial of service via network
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): prior to 8.22
Description:   A vulnerability was reported in Ipswitch IMail Server. A remote authenticated user can cause denial of service conditions.

The server does not properly process user-supplied input to the IMAP LIST command. A remote authenticated user can send a specially crafted LIST command with approximately 8000 bytes to trigger a memory allocation error in some internal string parsing routines. As a result, the IMAP daemon will crash.

The vendor was notified on September 8, 2005.

iDEFENSE reported this vulnerability.

The original advisory is available at:

Impact:   A remote authenticated user can the target IMAP service to crash.
Solution:   The vendor has issued a fixed version (IMail Server 8.22), available at:

The fix is also included in Ipswitch Collaboration Suite 2.02, available at:

Vendor URL: (Links to External Site)
Cause:   State error
Underlying OS:  Windows (NT), Windows (2000), Windows (2003), Windows (XP)

Message History:   None.

 Source Message Contents

Subject:  [Full-disclosure] iDEFENSE Security Advisory 12.06.05: Ipswitch

Ipswitch IMail IMAP List Command DoS Vulnerability

iDEFENSE Security Advisory 12.06.05
December 6, 2005


Ipswitch Imail Server is an email server that is part of the IpSwitch
Collaboration suit. Imail Supports POP3, SMTP, IMAP and web based email


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 (, 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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Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDEFENSE. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically, please
email for permission.

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.

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