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

First published: Thu Jul 30 2009(Updated: )

Netscape Portable Runtime (NSPR) provides platform independence for non-GUI<br>operating system facilities. These facilities include threads, thread<br>synchronization, normal file and network I/O, interval timing, calendar<br>time, basic memory management (malloc and free), and shared library linking.<br>Network Security Services (NSS) is a set of libraries designed to support<br>the cross-platform development of security-enabled client and server<br>applications. Applications built with NSS can support SSLv2, SSLv3, TLS,<br>and other security standards.<br>These updated packages upgrade NSS from the previous version, 3.12.2, to a<br>prerelease of version 3.12.4. The version of NSPR has also been upgraded<br>from 4.7.3 to 4.7.4. <br>Moxie Marlinspike reported a heap overflow flaw in a regular expression<br>parser in the NSS library used by browsers such as Mozilla Firefox to match<br>common names in certificates. A malicious website could present a<br>carefully-crafted certificate in such a way as to trigger the heap<br>overflow, leading to a crash or, possibly, arbitrary code execution with<br>the permissions of the user running the browser. (CVE-2009-2404)<br>Note: in order to exploit this issue without further user interaction in<br>Firefox, the carefully-crafted certificate would need to be signed by a<br>Certificate Authority trusted by Firefox, otherwise Firefox presents the<br>victim with a warning that the certificate is untrusted. Only if the user<br>then accepts the certificate will the overflow take place.<br>Dan Kaminsky discovered flaws in the way browsers such as Firefox handle<br>NULL characters in a certificate. If an attacker is able to get a<br>carefully-crafted certificate signed by a Certificate Authority trusted by<br>Firefox, the attacker could use the certificate during a man-in-the-middle<br>attack and potentially confuse Firefox into accepting it by mistake.<br>(CVE-2009-2408)<br>Dan Kaminsky found that browsers still accept certificates with MD2 hash<br>signatures, even though MD2 is no longer considered a cryptographically<br>strong algorithm. This could make it easier for an attacker to create a<br>malicious certificate that would be treated as trusted by a browser. NSS<br>now disables the use of MD2 and MD4 algorithms inside signatures by<br>default. (CVE-2009-2409)<br>These version upgrades also provide a fix for the following bug:<br><li> SSL client authentication failed against an Apache server when it was </li> using the mod_nss module and configured for NSSOCSP. On the client side,<br>the user agent received an error message that referenced "Error Code:<br><li>12271" and stated that establishing an encrypted connection had failed</li> because the certificate had been rejected by the host.<br>On the server side, the nss_error_log under /var/log/httpd/ contained the<br>following message:<br>[error] Re-negotiation handshake failed: Not accepted by client!?<br>Also, /var/log/httpd/error_log contained this error:<br>SSL Library Error: -8071 The OCSP server experienced an internal error<br>With these updated packages, the dependency problem which caused this<br>failure has been resolved so that SSL client authentication with an<br>Apache web server using mod_nss which is configured for NSSOCSP succeeds<br>as expected. Note that if the presented client certificate is expired,<br>then access is denied, the user agent is presented with an error message<br>about the invalid certificate, and the OCSP queries are seen in the OCSP<br>responder. Also, similar OCSP status verification happens for SSL server<br>certificates used in Apache upon instance start or restart. (BZ#508027)<br>All users of nspr and nss are advised to upgrade to these updated packages,<br>which resolve these issues.

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