RHSA-2009:1184: Critical: nspr and nss security and bug fix update

Netscape Portable Runtime (NSPR) provides platform independence for non-GUIoperating system facilities. These facilities include threads, threadsynchronization, normal file and network I/O, interval timing, calendartime, basic memory management (malloc and free), and shared library linking.Network Security Services (NSS) is a set of libraries designed to supportthe cross-platform development of security-enabled client and serverapplications. 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 aprerelease of version 3.12.4. The version of NSPR has also been upgradedfrom 4.7.3 to 4.7.4. Moxie Marlinspike reported a heap overflow flaw in a regular expressionparser in the NSS library used by browsers such as Mozilla Firefox to matchcommon names in certificates. A malicious website could present acarefully-crafted certificate in such a way as to trigger the heapoverflow, leading to a crash or, possibly, arbitrary code execution withthe permissions of the user running the browser. (CVE-2009-2404)Note: in order to exploit this issue without further user interaction inFirefox, the carefully-crafted certificate would need to be signed by aCertificate Authority trusted by Firefox, otherwise Firefox presents thevictim with a warning that the certificate is untrusted. Only if the userthen accepts the certificate will the overflow take place.Dan Kaminsky discovered flaws in the way browsers such as Firefox handleNULL characters in a certificate. If an attacker is able to get acarefully-crafted certificate signed by a Certificate Authority trusted byFirefox, the attacker could use the certificate during a man-in-the-middleattack and potentially confuse Firefox into accepting it by mistake.(CVE-2009-2408)Dan Kaminsky found that browsers still accept certificates with MD2 hashsignatures, even though MD2 is no longer considered a cryptographicallystrong algorithm. This could make it easier for an attacker to create amalicious certificate that would be treated as trusted by a browser. NSSnow disables the use of MD2 and MD4 algorithms inside signatures bydefault. (CVE-2009-2409)These version upgrades also provide a fix for the following bug: SSL client authentication failed against an Apache server when it was using the modnss module and configured for NSSOCSP. On the client side,the user agent received an error message that referenced "Error Code:12271" and stated that establishing an encrypted connection had failed because the certificate had been rejected by the host.On the server side, the nsserrorlog under /var/log/httpd/ contained thefollowing message:[error] Re-negotiation handshake failed: Not accepted by client!?Also, /var/log/httpd/errorlog contained this error:SSL Library Error: -8071 The OCSP server experienced an internal errorWith these updated packages, the dependency problem which caused thisfailure has been resolved so that SSL client authentication with anApache web server using modnss which is configured for NSSOCSP succeedsas expected. Note that if the presented client certificate is expired,then access is denied, the user agent is presented with an error messageabout the invalid certificate, and the OCSP queries are seen in the OCSPresponder. Also, similar OCSP status verification happens for SSL servercertificates used in Apache upon instance start or restart. (BZ#508027)All users of nspr and nss are advised to upgrade to these updated packages,which resolve these issues.