Synopsis

Critical: nspr and nss security update

Type/Severity

Security Advisory: Critical

Topic

Updated nspr and nss packages that fix security issues are now available
for Red Hat Enterprise Linux 5.2 Extended Update Support.

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

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.

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

Affected Products

• Red Hat Enterprise Linux Server - Extended Update Support 5.2 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support 5.2 ia64
• Red Hat Enterprise Linux Server - Extended Update Support 5.2 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 5.2 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 5.2 ppc

Fixes

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

CVEs

• CVE-2009-2404
• CVE-2009-2408
• CVE-2009-2409

References

• http://www.redhat.com/security/updates/classification/#critical

This erratum does not contain any packages.