9.3 - RHSA-2009:1186

Problem Description:

Updated nspr and nss packages that fix security issues, bugs, and add an enhancement are now available for Red Hat Enterprise Linux 5.

This update has been rated as having critical security impact by the Red Hat Security Response Team.

The packages with this update are identical to the packages released by RHBA-2009:1161 on the 20th of July 2009. They are being reissued as a Red Hat Security Advisory as they fixed a number of security issues that were made public today. If you are installing these packages for the first time, they also provide a number of bug fixes and add an enhancement, as detailed in RHBA-2009:1161. Since the packages are identical, there is no need to install this update if RHBA-2009:1161 has already been installed.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Desktop (v. 5 client) - i386, x86_64 RHEL Desktop Workstation (v. 5 client) - i386, x86_64 Red Hat Enterprise Linux (v. 5 server) - i386, ia64, ppc, s390x, x86_64

3. Description:

Netscape Portable Runtime (NSPR) provides platform independence for non-GUI operating system facilities. These facilities include threads, thread synchronization, normal file and network I/O, interval timing, calendar time, basic memory management (malloc and free), and shared library linking.

Network Security Services (NSS) is a set of libraries designed to support the cross-platform development of security-enabled client and server applications. Applications built with NSS can support SSLv2, SSLv3, TLS, and other security standards.

These updated packages upgrade NSS from the previous version, 3.12.2, to a prerelease of version 3.12.4. The version of NSPR has also been upgraded from 4.7.3 to 4.7.4.

Moxie Marlinspike reported a heap overflow flaw in a regular expression parser in the NSS library used by browsers such as Mozilla Firefox to match common names in certificates. A malicious website could present a carefully-crafted certificate in such a way as to trigger the heap overflow, leading to a crash or, possibly, arbitrary code execution with the permissions of the user running the browser. (CVE-2009-2404)

Note: in order to exploit this issue without further user interaction in Firefox, the carefully-crafted certificate would need to be signed by a Certificate Authority trusted by Firefox, otherwise Firefox presents the victim with a warning that the certificate is untrusted. Only if the user then accepts the certificate will the overflow take place.

Dan Kaminsky discovered flaws in the way browsers such as Firefox handle NULL characters in a certificate. If an attacker is able to get a carefully-crafted certificate signed by a Certificate Authority trusted by Firefox, the attacker could use the certificate during a man-in-the-middle attack and potentially confuse Firefox into accepting it by mistake. (CVE-2009-2408)

Dan Kaminsky found that browsers still accept certificates with MD2 hash signatures, even though MD2 is no longer considered a cryptographically strong algorithm. This could make it easier for an attacker to create a malicious certificate that would be treated as trusted by a browser. NSS now disables the use of MD2 and MD4 algorithms inside signatures by default. (CVE-2009-2409)

All users of nspr and nss are advised to upgrade to these updated packages, which resolve these issues and add an enhancement.

4. Solution:

Before applying this update, make sure that all previously-released errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use the Red Hat Network to apply this update are available at http://kbase.redhat.com/faq/docs/DOC-11259

5. Bugs fixed (http://bugzilla.redhat.com/):

510197 - CVE-2009-2409 deprecate MD2 in SSL cert validation (Kaminsky) 510251 - CVE-2009-2408 firefox/nss: doesn't handle NULL in Common Name properly 512912 - CVE-2009-2404 nss regexp heap overflow