Updated OpenSSL packages are available that fix a potential timing-based attack and a modified Bleichenbacher attack. [Updated 30 May 2003] Added missing i686 packages.
OpenSSL is a commercial-grade, full-featured, open source toolkit that implements the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols, and provides a full-strength general purpose cryptography library. Researchers discovered a timing attack on RSA keys. Applications making use of OpenSSL are generally vulnerable to such an attack, unless RSA blinding has been turned on. OpenSSL does not use RSA blinding by default and most applications do not enable RSA blinding. A local or remote attacker could use this attack to obtain the server's private key by determining factors using timing differences on (1) the number of extra reductions during Montgomery reduction, and (2) the use of different integer multiplication algorithms (Karatsuba and normal). In order for an attack to be sucessful, an attacker must have good network conditions that allow small changes in timing to be reliably observed. Additionally, the SSL and TLS components for OpenSSL allow remote attackers to perform an unauthorized RSA private key operation via a modified Bleichenbacher attack. This attack (also known as the Klima-Pokorny-Rosa attack) uses a large number of SSL or TLS connections using PKCS #1 v1.5 padding to cause OpenSSL to leak information regarding the relationship between ciphertext and the associated plaintext. These erratum packages contain a patch provided by the OpenSSL group that enables RSA blinding by default, and protects against the Klima-Pokorny-Rosa attack. Because server applications are affected by these vulnerabilities, we advise users to restart all services that use OpenSSL functionality or, alternatively, reboot their systems after installing these updates.