Ipswitch Collaboration Suite IMAP EXAMINE Buffer Overflow Vulnerability 

iDEFENSE Security Advisory 03.10.05
www.idefense.com/application/poi/display?id=216&type=vulnerabilities
March 10, 2005

I. BACKGROUND

Ipswitch Collaboration Suite (ICS) is a comprehensive communication and 
collaboration solution for Microsoft Windows with a customer base of 
over 53 million users. More information is available on the vendor's 
website:

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

II. DESCRIPTION

Exploitation of a remote buffer overflow within the IMAP daemon of 
Ipswitch Collaboration Suite allows attackers to execute arbitrary code
with administrator privileges.

The vulnerability specifically exists due to insufficient handling of
overly long arguments passed to the EXAMINE handler function. The 
EXAMINE command selects a mailbox so that messages within the mailbox 
may be accessed with read-only privileges. EXAMINE requests with 
malformed mailbox names of 259 bytes will overwrite the saved stack 
frame pointer, resulting in potential process execution control. It 
should be noted that IMAP will append a '/' character to your supplied 
mailbox name so the most significant byte of the frame pointer will be 
0x2e. The output below shows successful control of the frame pointer.

(668.f8): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.

eax=00000006 ebx=008943b0 ecx=42424242
edx=00c8fad4 esi=008943b0 edi=00000013
eip=0078626d esp=00c9fd20 ebp=2e434343
iopl=0         nv up ei pl zr na po nc
cs=001b ss=0023 ds=0023 es=0023
fs=0038 gs=0000 efl=00000246
0078626d ??               ???

Frame pointer overwrites may allow attackers to redirect program flow 
when the current function returns. It should be noted that the IMAP 
EXAMINE command is only available after successful authentication.

III. ANALYSIS

Successful exploitation allows remote attackers to execute arbitrary 
code under administrator privileges. The EXAMINE IMAP command is only 
valid after authentication has occurred, however due to the nature of 
IMAP servers serving a large user base, this requirement only slightly 
reduces exposure to the vulnerability.

IV. DETECTION

iDEFENSE has confirmed that the IMAP4 daemon (IMAP4d32.exe ver. 
12.8.27.14) shipping with IMail Server version 8.13 is vulnerable. 
IMail Server is now packaged as part of Ipswitch Collaboration Suite.
It is suspected that earlier versions are vulnerable as well.
 
V. WORKAROUND

Use application level content filtering on overly long IMAP commands.

VI. VENDOR RESPONSE

This vulnerability is addressed in IMail Server 8.15 Hotfix 1 (February
3, 2005), which is available for download at:

   ftp://ftp.ipswitch.com/Ipswitch/Product_Support/IMail/IM815HF1.exe

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-0707 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

03/02/2005  Initial vendor notification
03/08/2005  Initial vendor response
03/10/2005  Public disclosure

IX. CREDIT

Nico Steinhardt is credited with this discovery.

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X. LEGAL NOTICES

Copyright (c) 2005 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.
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.