I. BACKGROUND
Mozilla Thunderbird is an open source electronic mail client and news
reader. Multipurpose Internet Message Extensions (MIME) is a standard
that defines how non-text attachments and other data are handled in
electronic mail. The external-body MIME type is used for retrieving a
resource that is referenced in the message, such as an attachment. For
more information, see the vendor's website at the following URL.
http://www.mozilla.com/en-US/thunderbird/
II. DESCRIPTION
Remote exploitation of a heap based buffer overflow vulnerability in
Mozilla Organization's Thunderbird could allow an attacker to execute
arbitrary code with the privileges of the current user.
The vulnerability exists when parsing the external-body MIME type in an
electronic mail. When calculating the number of bytes to allocate for a
heap buffer, sufficient space is not reserved for all of the data being
copied into the buffer. This results in up to 3 bytes of the buffer
being overflowed, potentially allowing for the execution of arbitrary
code.
III. ANALYSIS
Exploitation of this vulnerability results in the execution of arbitrary
code with the privileges of the user running Thunderbird. Exploitation
requires that an attacker social engineers a user into viewing a
malicious message in Thunderbird. If the 'View->Message Pane' option is
turned on (the "Preview" pane), which is the default, then all a
targeted user has to do is select the message in the browsing pane.
Once the message is previewed, the vulnerability will be triggered.
IV. DETECTION
iDefense has confirmed the existence of this vulnerability in
Thunderbird version 2.0.0.9 on Linux and Windows. Previous versions may
also be affected.
V. WORKAROUND
Setting the "mailnews.display.disallow_mime_handlers" configuration
property to any value >= 3 will prevent the vulnerable code from being
triggered.
VI. VENDOR RESPONSE
The Mozilla Foundation has addressed this vulnerability by releasing
version 2.0.0.12 of Thunderbird. For more information, refer to their
advisory at the following URL.
http://www.mozilla.org/security/announce/2008/mfsa2008-12.html
VII. CVE INFORMATION
The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2008-0304 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
01/14/2008 Initial vendor notification
01/14/2008 Initial vendor response
02/26/2008 Coordinated public disclosure
IX. CREDIT
This vulnerability was reported to VeriSign iDefense by regenrecht.
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http://labs.idefense.com/methodology/vulnerability/vcp.php
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X. LEGAL NOTICES
Copyright © 2008 iDefense, Inc.
Permission is granted for the redistribution of this alert electronically. It may not be edited in
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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.
