Vulnerability Note VU#592796

Mozilla Network Security Services (NSS) fails to properly handle the client master key

Overview

A vulnerability in the way Mozilla Network Security Services (NSS) handles the client master key may lead to execution of arbitrary code.

I. Description

The SSLv2 protocol uses a client master key to generate all subsequent session keys. The validity of the client master key is determined during phase one of the SSL handshake. Mozilla NSS library contains a vulnerability in the way client master keys with invalid length values are handled that may result in a buffer overflow. According to the Mozilla Foundation Security Advisory (MFSA) 2007-06:

Servers that use NSS for the SSLv2 protocol can be exploited by a client that presents a "Client Master Key" with invalid length values in any of several fields that are used without adequate error checking. This can lead to a buffer overflow that presumably could be exploitable.

Note that this vulnerability may affect any application that uses the Mozilla NSS library.

II. Impact

A remote, unauthenticated attacker may be able to execute arbitrary code with the privileges of the user who is running the vulnerable application or cause a denial of service.

III. Solution

Apply an update

According to the Mozilla Foundation Security Advisory 2007-06, this vulnerability is addressed in Firefox 2.0.0.2, Firefox 1.5.0.10, SeaMonkey 1.0.8, and NSS 3.11.5.

Disable SSLv2

Disabling support for the SSLv2 protocol appears to prevent exploitation of this vulnerability. Instructions for disabling the SSLv2 protocol support in Firefox and Thunderbird can be found in the Mozilla Foundation Security Advisory 2007-06. SSLv2 is disabled by default in Firefox 2.

Systems Affected

Vendor	Status	Date Notified
Fedora Project	Vulnerable	7-Mar-2007
Gentoo Linux	Vulnerable	5-Apr-2007
Mandriva, Inc.	Vulnerable	7-Mar-2007
Mozilla	Vulnerable	27-Feb-2007
Red Hat, Inc.	Vulnerable	7-Mar-2007
rPath	Vulnerable	7-Mar-2007
Slackware Linux Inc.	Vulnerable	5-Apr-2007
Sun Microsystems, Inc.	Vulnerable	5-Apr-2007
SUSE Linux	Vulnerable	7-Mar-2007
Ubuntu	Vulnerable	7-Mar-2007

References

Credit

This vulnerability was reported in Mozilla Foundation Security Advisory 2007-06. Mozilla credits iDefense with reporting this issue.

This document was written by Chris Taschner.

Other Information

Date Public:	2007-02-23
Date First Published:	2007-03-07
Date Last Updated:	2007-04-05
CERT Advisory:
CVE-ID(s):	CVE-2007-0009
NVD-ID(s):	CVE-2007-0009
US-CERT Technical Alerts:
Metric:	12.72
Document Revision:	57

If you have feedback, comments, or additional information about this vulnerability, please send us email.

Produced 2007 by US-CERT, a government organization
Disclaimers and copyright information

Get Adobe Reader