RHSA-2016:0301: openssl security update

Description

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL v2/v3)and Transport Layer Security (TLS v1) protocols, as well as afull-strength, general purpose cryptography library.A padding oracle flaw was found in the Secure Sockets Layer version 2.0(SSLv2) protocol. An attacker can potentially use this flaw to decryptRSA-encrypted cipher text from a connection using a newer SSL/TLS protocolversion, allowing them to decrypt such connections. This cross-protocolattack is publicly referred to as DROWN. (CVE-2016-0800)Note: This issue was addressed by disabling the SSLv2 protocol by defaultwhen using the 'SSLv23' connection methods, and removing support for weakSSLv2 cipher suites. For more information, refer to the knowledge basearticle linked to in the References section.A flaw was found in the way malicious SSLv2 clients could negotiate SSLv2ciphers that have been disabled on the server. This could result in weakSSLv2 ciphers being used for SSLv2 connections, making them vulnerable toman-in-the-middle attacks. (CVE-2015-3197)A side-channel attack was found that makes use of cache-bank conflicts onthe Intel Sandy-Bridge microarchitecture. An attacker who has the abilityto control code in a thread running on the same hyper-threaded core as thevictim's thread that is performing decryption, could use this flaw torecover RSA private keys. (CVE-2016-0702)A double-free flaw was found in the way OpenSSL parsed certain malformedDSA (Digital Signature Algorithm) private keys. An attacker could createspecially crafted DSA private keys that, when processed by an applicationcompiled against OpenSSL, could cause the application to crash.(CVE-2016-0705)An integer overflow flaw, leading to a NULL pointer dereference or aheap-based memory corruption, was found in the way some BIGNUM functions ofOpenSSL were implemented. Applications that use these functions with largeuntrusted input could crash or, potentially, execute arbitrary code.(CVE-2016-0797)Red Hat would like to thank the OpenSSL project for reporting these issues.Upstream acknowledges Nimrod Aviram and Sebastian Schinzel as the originalreporters of CVE-2016-0800 and CVE-2015-3197; Adam Langley(Google/BoringSSL) as the original reporter of CVE-2016-0705; Yuval Yarom(University of Adelaide and NICTA), Daniel Genkin (Technion and Tel AvivUniversity), Nadia Heninger (University of Pennsylvania) as the originalreporters of CVE-2016-0702; and Guido Vranken as the original reporter ofCVE-2016-0797.All openssl users are advised to upgrade to these updated packages,which contain backported patches to correct these issues. For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted.