Vulnerability Note VU#931588

Ethereal fails to properly decode BGP packets containing MPLS IPv6 labels

Overview

Ethereal contains a vulnerability in the way the Border Gateway Protocol (BGP) protocol dissector decodes Multiprotocol Label Switching (MPLS) IPv6 labels.

I. Description

Ethereal is a network traffic analysis package. It includes the ability to decode packets containing BGP data. According to RFC3031, an MPLS label is an identifier used to represent the Forwarding Equivalence Class (FEC) to which that packet is assigned. There is a buffer overflow vulnerability in the way the BGP protocol dissector decodes MPLS IPv6 labels.

According to the e-matters Security Advisory:

When parsing a BGP Packet with a MPLS IPv6 label up to 13 bytes on the stack may be overwritten with arbitrary data. Due to the stacklayout exploitability seems unlikly and was therefore not tested.

II. Impact

A remote, unauthenticated attacker could cause Ethereal to crash or potentially execute code of the attacker's choice.

III. Solution

Upgrade

Upgrade to version 0.10.3 or later.

Note: Ethereal is considered BETA software at this time.

Disable Dissector

If you are unable to upgrade to version 0.10.3 or later, you can disable the BGP protocol dissector by performing the following actions in Ethereal:

(for Ethereal versions 0.8.x and 0.9.x)

(for Ethereal versions 0.10.x)

However, it is strongly encouraged to upgrade to version 0.10.3 or later.

Systems Affected

Vendor	Status	Date Notified	Date Updated
Ethereal	Vulnerable	25-Mar-2004

References

http://security.e-matters.de/advisories/032004.html
http://www.ethereal.com/appnotes/enpa-sa-00013.html
http://secunia.com/advisories/11185/
http://www.ietf.org/rfc/rfc1771.txt
http://www.ietf.org/rfc/rfc1772.txt
http://www.ietf.org/rfc/rfc3031.txt

Credit

Ethereal credits Stefan Esser for reporting this vulnerability.

This document was written by Damon Morda.

Other Information

Date Public:	2004-03-22
Date First Published:	2004-03-25
Date Last Updated:	2004-03-25
CERT Advisory:
CVE-ID(s):	CAN-2004-0176
NVD-ID(s):	CAN-2004-0176
US-CERT Technical Alerts:
Metric:	2.89
Document Revision:	10

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