CVE-2016-2178

La función dsa_sign_setup en crypto/dsa/dsa_ossl.c en OpenSSL hasta la versión 1.0.2h no asegura correctamente la utilización de operaciones de tiempo constante, lo que facilita a usuarios locales descubrir una clave privada DSA a través de un ataque de sincronización de canal lateral.

It was discovered that OpenSSL did not always use constant time operations when computing Digital Signature Algorithm (DSA) signatures. A local attacker could possibly use this flaw to obtain a private DSA key belonging to another user or service running on the same system.

USN-3087-1 fixed vulnerabilities in OpenSSL. The fix for CVE-2016-2182 was incomplete and caused a regression when parsing certificates. This update fixes the problem. Shi Lei discovered that OpenSSL incorrectly handled the OCSP Status Request extension. A remote attacker could possibly use this issue to cause memory consumption, resulting in a denial of service. Guido Vranken discovered that OpenSSL used undefined behaviour when performing pointer arithmetic. A remote attacker could possibly use this issue to cause OpenSSL to crash, resulting in a denial of service. This issue has only been addressed in Ubuntu 16.04 LTS in this update. CAsar Pereida, Billy Brumley, and Yuval Yarom discovered that OpenSSL did not properly use constant-time operations when performing DSA signing. A remote attacker could possibly use this issue to perform a cache-timing attack and recover private DSA keys. Quan Luo discovered that OpenSSL did not properly restrict the lifetime of queue entries in the DTLS implementation. A remote attacker could possibly use this issue to consume memory, resulting in a denial of service. Shi Lei discovered that OpenSSL incorrectly handled memory in the TS_OBJ_print_bio function. A remote attacker could possibly use this issue to cause a denial of service. It was discovered that the OpenSSL incorrectly handled the DTLS anti-replay feature. A remote attacker could possibly use this issue to cause a denial of service. Various other issues were also addressed.