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AUSCERT External Security Bulletin Redistribution
ESB-2007.0537 -- [Win]
Trillian Instant Messenger client fails to properly handle malformed URIs
20 July 2007
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AusCERT Security Bulletin Summary
---------------------------------
Product: Trillian Instant Messenger
Publisher: US-CERT
Operating System: Windows
Impact: Execute Arbitrary Code/Commands
Access: Remote/Unauthenticated
CVE Names: CVE-2007-3832 CVE-2007-3833
Original Bulletin: http://www.kb.cert.org/vuls/id/786920
Revision History: July 20 2007: Updated to reflect US-CERT update
July 19 2007: Added CVE Number
July 18 2007: Initial Release
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Vulnerability Note VU#786920
Trillian Instant Messenger client fails to properly handle malformed URIs
Overview
The Trillian Instant Messaging client contains a buffer overflow
vulnerability that may allow an attacker to execute code.
I. Description
A Uniform Resource Identifier (URI) is a string of characters that can
be used to identify a location, resource, or protocol. The Trillian
Instant Messenger client is an IM application that supports multiple
services, including AOL Instant Messenger. Trillian registers itself
as the default handler for aim: URIs during installation. Web browsers
may pass URIs to other applications that have been registered to
handle them.
A buffer overflow vulnerability exists in the Trillian Instant
Messenger client. An attacker may exploit this vulnerability by
convincing a user to open a malformed aim: URI inside of a web
browser. When the web browser passes the malformed URI to the Trillian
Instant Messenger client, the overflow may be triggered.
Note that some web browsers may present a dialog box warning that the
aim: URI is being handed off to another program.
II. Impact
A remote, unauthenticated attacker may be able to execute arbitrary
code with the privileges of the user running Trillian.
III. Solution
We are currently unaware of a practical solution to this problem.
Unregister the AIM protocols
Disabling the AIM protocol handler can mitigate this vulnerability. To
unregister the protocol handler, delete or rename the following
registry key:
HKEY_CLASSES_ROOT\AIM\
Note that when Trillian (trillian.exe) is started, it will attempt to
recreate or repair the registry key. On Windows XP SP2 by default,
Administrators and Power Users have permissions to modify the registry
key. To prevent Trillian from recreating the registry key, run
Trillian with a limited user account. Alternatively, change or delete
the value for
HKEY_CLASSES_ROOT\AIM\shell\open\command
and [21]change permissions so that the appropriate user groups can not
recreate or repair the key.
Block access to aim: URIs
Administrators may partially mitigate this vulnerability by blocking
access to the aim: URI using proxy server access control lists or the
appropriate content filtering rule.
Systems Affected
Vendor Status Date Updated
America Online, Inc. Not Vulnerable 16-Jul-2007
http://www.kb.cert.org/vuls/id/RGII-756S8E
Cerulean Studios Vulnerable 16-Jul-2007
http://www.kb.cert.org/vuls/id/RGII-756RFW
References
http://www.xs-sniper.com/nmcfeters/Cross-App-Scripting-2.html
http://en.wikipedia.org/wiki/Uniform_Resource_Identifier
http://secunia.com/advisories/26086/
http://technet2.microsoft.com/windowsserver/en/library/2621d47b-714b-4549-8f21-29ea082ed76b1033.mspx?mfr=true
Credit
This issue was disclosed by Nate Mcfeters, Billy (BK) Rios, Raghav
"the Pope" Dube.
This document was written by Ryan Giobbi.
Other Information
Date Public 07/15/2007
Date First Published 07/16/2007 04:40:45 PM
Date Last Updated 07/18/2007
CERT Advisory
CVE Name
Metric 23.76
Document Revision 25
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