Vulnerability Note VU#591820

Ethereal fails to properly decode Transaction IDs within TCAP packets

Overview

Ethereal contains a vulnerability in the way the Transaction Capabilities Application Part (TCAP) protocol dissector parses ASN.1 encoded Transaction IDs within TCAP packets.

I. Description

Ethereal is a network traffic analysis package. It includes the ability to decode packets containing TCAP data. The TCAP protocol is designed to enable advanced network telephony services between signaling points. For instance, when dialing an 800, 888, or 900 number, TCAP is used to determine the routing numbers for these digits.

According to an IETF Draft,

TCAP messages are designed for accessing databases or other switches to retrieve information or invoke features. TCAP enables the deployment of advanced intelligent network services by supporting non-circuit related information exchange between signaling points using the signaling connection control part (SCCP) connectionless service for message transport.

...

The Transaction ID is a reference to correlate messages within the same transaction and associate the TCAP transaction with a specific application at the originating and destination signaling points.

There is a buffer overflow vulnerability in the way the TCAP protocol dissector parses ASN.1 encoded Transaction IDs within TCAP packets. Exploitation of this vulnerability could allow for arbitrary code execution.

II. Impact

A remote, unauthenticated attacker could 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 TCAP protocol dissector by performing the following actions in Ethereal:

(for Ethereal versions 0.9.x)

(for Ethereal versions 0.10.x)

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/proceedings/99nov/I-D/draft-ietf-sigtran-tcap-perf-req-00.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:	9.82
Document Revision:	17

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