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[security-alerts] FW: iDefense Security Advisory 12.09.05: Ethereal OSPF Protocol DissectorBuffer Overflow Vulnerability

> -----Original Message-----
> From: 
> idlabs-advisories-bounces+vladimir.kazennov=billing.ru@xxxxxxx
> defense.com 
> [mailto:idlabs-advisories-bounces+vladimir.kazennov=billing.ru
> @lists.idefense.com] On Behalf Of iDEFENSE Labs Security Advisories
> Sent: Saturday, December 10, 2005 12:31 AM
> To: Idlabs-Advisories@xxxxxxxxxxxxxxxxxx
> Subject: iDefense Security Advisory 12.09.05: Ethereal OSPF 
> Protocol DissectorBuffer Overflow Vulnerability
> Ethereal OSPF Protocol Dissector Buffer Overflow Vulnerability
> iDefense Security Advisory 12.09.05
> www.idefense.com/application/poi/display?id=349&type=vulnerabilities
> December 9, 2005
> Ethereal is a full featured open source network protocol analyzer.
> For more information, see http://www.ethereal.com/
> Remote exploitation of an input validation vulnerability in the OSPF
> protocol dissectors within Ethereal, as included in various vendors
> operating system distributions, could allow attackers to crash the
> vulnerable process or potentially execute arbitrary code.
> The affected Ethereal component is used to analyse Open Shortest Path
> First (OSPF) Interior Gateway Protocol (IGP), as specified in 
> RFC-2178.
> The vulnerability specifically exists due to no bounds checking being
> performed in the dissect_ospf_v3_address_prefix() function. This
> function takes user-supplied binary data and attempts to 
> convert it into
> a human readable string. This function uses a fixed length buffer on
> the stack to store the constructed string but performs no 
> checks on the
> length of the input. If the generated output length from the input
> exceeds the size of the buffer, a stack-based overflow occurs.
> Successful exploitation allows remote attackers to perform a 
> DoS against
> a running instance of Ethereal and may, under certain conditions,
> potentially allow the execution of arbitrary code. As the overflow
> string is generated from a format string converting binary values into
> their hexadecimal (base 16) equivalent characters, it can 
> contain only a
> limited subset of all possible characters, and the length of an
> overflow is only able to be controlled to within the three characters.
> This may prevent exploit ability on some platforms; however, it may be
> possible that these constraints will not prevent exploitation on
> others.
> iDefense has confirmed the existence of this vulnerability in the
> ethereal-0.10.12 RPM from Red Hat Fedora Core 3. It is suspected that
> previous versions containing the OSPF dissector code are also
> vulnerable.
> Disable the OSPF packet dissector in Ethereal by performing the
> following actions as the user invoking Ethereal, typically root.
> Create the .ethereal directory:
>  # mkdir ~/.ethereal
> You can safely ignore the following error:
>  mkdir: cannot create directory '/root/.ethereal': File exists
> Add the OSPF dissector to the list of protocols to ignore.
>  # echo ospf >> ~/.ethereal/disabled_protos
> This workaround will prevent Ethereal from parsing the 
> contents of OSPF
> packets, which prevents exposure to the vulnerability.
> A source patch is available from the main ethereal SVN Repository:
> http://anonsvn.ethereal.com/viewcvs/viewcvs.py/trunk/epan/dissectors/
>  packet-ospf.c?rev=16507&view=markup
> The Common Vulnerabilities and Exposures (CVE) project has 
> assigned the
> name CVE-2005-3651 to this issue. This is a candidate for inclusion in
> the CVE list (http://cve.mitre.org), which standardizes names for
> security problems.
> 11/14/2005 Initial vendor notification
> 11/14/2005 Initial vendor response
> 12/09/2005 Public disclosure
> The discoverer of this vulnerability wishes to remain anonymous.
> Get paid for vulnerability research
> http://www.iDefense.com/poi/teams/vcp.jsp
> Free tools, research and upcoming events
> http://labs.iDefense.com
> Copyright (c) 2005 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
> email customerservice@xxxxxxxxxxxx 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.


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