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iDefense Security Advisory 10.23.07: IBM Lotus Notes Client TagAttributeListCopy Buffer Overflow Vulnerability



IBM Lotus Notes Client TagAttributeListCopy Buffer Overflow Vulnerability

iDefense Security Advisory 10.23.07
http://labs.idefense.com/intelligence/vulnerabilities/
Oct 23, 2007

I. BACKGROUND

IBM Corp.'s Lotus Notes software is an integrated desktop client option
for accessing e-mail, calendars and applications on an IBM Corp. Lotus
Domino server. More information can be found by visiting the URL below.

http://www-142.ibm.com/software/sw-lotus/products/product4.nsf/wdocs/noteshomepage

II. DESCRIPTION

Remote exploitation of a buffer overflow vulnerability in IBM Corp.'s
Lotus Notes mail user agent could allow attackers to execute arbitrary
code in the context of the current user.

When a Lotus Notes user receives an HTML email, the HTML is converted to
a format resembling RTF (Rich Text Format). When messages are replied
to, forwarded or copied to the clipboard, the e-mail format is
converted again.

The buffer overflow is the result of a call to "Cstrcpy" when copying an
attacker supplied variable length string into a fixed-sized stack
buffer. The overflow occurs at the "Cstrcpy" call inside the
"TagAttributeListCopy" function in nnotes.dll.

III. ANALYSIS

Exploitation allows attackers to execute arbitrary code in the context
of the recipient of the message. In order to be successful, an attacker
must social engineer the victim into processing a specially crafted
message in a certain way. Specifically, the victim must either forward,
reply with history, or copy the message to the clipboard in order to
trigger the vulnerability.

Additionally, non-printable ASCII characters are converted to the LMBCS
(Lotus MultiByte Character Set) before the overflow occurs. This
complicates, but does not prevent, exploitation.

IV. DETECTION

iDefense confirmed the existence of this vulnerability in version 7.0.2
of IBM Corp.'s Lotus Notes. Additionally, versions 6.5.1, 6.5.3 and
7.0.1 were reported to be vulnerable. Other versions are suspected to
be vulnerable.

V. WORKAROUND

iDefense is currently unaware of any effective workaround for this
issue.

VI. VENDOR RESPONSE

IBM Lotus has addressed this vulnerability within versions 7.0.3 and 8.0
of Lotus Notes. For more information, visit the following URL.

http://www-1.ibm.com/support/docview.wss?rs=477&uid=swg21272930

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2007-4222 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

02/07/2007  Initial vendor notification
02/07/2007  Initial vendor response
10/23/2007  Coordinated public disclosure

IX. CREDIT

This vulnerability was reported to iDefense by UVInc.

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X. LEGAL NOTICES

Copyright © 2007 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.