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ESB-2007.0545 -- [Win][UNIX/Linux] -- Opera Software Opera Web Browser BitTorrent Dangling Pointer Vulnerability

Date: 20 July 2007

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             AUSCERT External Security Bulletin Redistribution

                    ESB-2007.0545 -- [Win][UNIX/Linux]
Opera Software Opera Web Browser BitTorrent Dangling Pointer Vulnerability
                               20 July 2007


        AusCERT Security Bulletin Summary

Product:              Opera Web Browser 9.21 and prior
Publisher:            iDefense
Operating System:     UNIX variants (UNIX, Linux, OSX)
Impact:               Execute Arbitrary Code/Commands
Access:               Remote/Unauthenticated

Original Bulletin:

Comment: This exploit requires the user to remove a malicious torrent file
         from the download manager in Opera.

- --------------------------BEGIN INCLUDED TEXT--------------------

Opera Software Opera Web Browser BitTorrent Dangling Pointer Vulnerability

iDefense Security Advisory 07.19.07
Jul 19, 2007


Opera is a cross-platform web browser. More information is available at


Remote exploitation of a dangling pointer vulnerability in Opera
Software ASA's Opera web browser could allow an attacker to execute
arbitrary code with the privileges of the logged in user.

Opera 9.2 supports BitTorrent downloads. When parsing a specially
crafted BitTorrent header, Opera uses memory that has already been
freed. This can result in an invalid object pointer being dereferenced,
and may allow for the execution of arbitrary code.  The vulnerability is
triggered when the user right clicks on the transfer and removes it.


Exploitation of this vulnerability allows an attacker to execute
arbitrary code on the affected host with the privileges of the logged
in user.  

The attacker must persuade a vulnerable user into clicking a link to a
BitTorrent file. The targeted user must subsequently remove the entry
from the download pane. The requirement to remove the torrent is not
considered to be a mitigating factor since it is natural for a user to
attempt to do so when a transfer is not progressing.


iDefense has confirmed the existence of this vulnerability in Opera
version 9.21 on Windows. Previous versions may also be affected.


iDefense is currently unaware of any workarounds for this issue.


Version 9.22 of Opera has been released to address this issue. More
information can be found at the following URL.


A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.


06/06/2007  Initial vendor notification
06/06/2007  Initial vendor response
07/19/2007  Coordinated public disclosure


This vulnerability was reported to iDefense by enhalos.

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Copyright  2007 iDefense, Inc.

Permission is granted for the redistribution of this alert
electronically. It may not be edited in any way without the express
written consent of iDefense. If you wish to reprint the whole or any
part of this alert in any other medium other than electronically,
please e-mail for 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.

- --------------------------END INCLUDED TEXT--------------------

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