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.

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.”

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Impact

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

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Solution

Upgrade

Upgrade to version 0.10.3 or later.

Note: Ethereal is considered BETA software at this time.

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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)

1. Select Edit->Protocols
2. Deselect the PGM protocol dissector from the list

(for Ethereal versions 0.10.x)

1. Select Analyze->Enabled Protocols
2. Disable the PGM protocol dissector from the list by unchecking its “Status” checkbox

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Vendor Information

433596

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Ethereal __ Affected

Updated: March 24, 2004

Status

Affected

Vendor Statement

Please see the Ethereal Security Bulletin at <http://www.ethereal.com/appnotes/enpa-sa-00013.html&gt;.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23433596 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://security.e-matters.de/advisories/032004.html&gt;
• <http://www.ethereal.com/appnotes/enpa-sa-00013.html&gt;
• <http://secunia.com/advisories/11185/&gt;
• <http://www.ietf.org/rfc/rfc3208.txt&gt;

Acknowledgements

Ethereal credits Stefan Esser for reporting this vulnerability.

This document was written by Damon Morda.

Other Information

CVE IDs:	CVE-2004-0176
Severity Metric:	4.04 Date Public: