Vulnerability Note VU#433596

Ethereal integer underflow when parsing malformed PGM packets with NAK lists

Overview

Ethereal fails to properly parse Pragmatic General Multicast (PGM) packets containing a crafted negative acknowledgement (NAK) list.

I. Description

Ethereal is a network traffic analysis package. It includes the ability to decode packets containing PGM data. There is a vulnerability in the way the PGM protocol dissector parses PGM data containing a crafted NAK list.

According to the e-matters Security Advisory:

"When parsing an PGM packet with a carefully crafted NakList a possible integer underflow can result in a very small stack-overflow. Due to the stacklayout code execution exploitation seems very unlikely."

II. Impact

A remote, unauthenticated attacker could cause Ethereal to crash or possibly execute arbitrary code on the vulnerable system.

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 PGM 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)

Systems Affected

Vendor	Status	Date Notified	Date Updated
Ethereal	Vulnerable	24-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/rfc3208.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:	2004-03-24
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:	4.04
Document Revision:	21

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