(RHSA-2016:0301) Important: openssl security update

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL v2/v3)
and Transport Layer Security (TLS v1) protocols, as well as a
full-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 decrypt
RSA-encrypted cipher text from a connection using a newer SSL/TLS protocol
version, allowing them to decrypt such connections. This cross-protocol
attack is publicly referred to as DROWN. (CVE-2016-0800)

Note: This issue was addressed by disabling the SSLv2 protocol by default
when using the ‘SSLv23’ connection methods, and removing support for weak
SSLv2 cipher suites. For more information, refer to the knowledge base
article linked to in the References section.

A flaw was found in the way malicious SSLv2 clients could negotiate SSLv2
ciphers that have been disabled on the server. This could result in weak
SSLv2 ciphers being used for SSLv2 connections, making them vulnerable to
man-in-the-middle attacks. (CVE-2015-3197)

A side-channel attack was found that makes use of cache-bank conflicts on
the Intel Sandy-Bridge microarchitecture. An attacker who has the ability
to control code in a thread running on the same hyper-threaded core as the
victim’s thread that is performing decryption, could use this flaw to
recover RSA private keys. (CVE-2016-0702)

A double-free flaw was found in the way OpenSSL parsed certain malformed
DSA (Digital Signature Algorithm) private keys. An attacker could create
specially crafted DSA private keys that, when processed by an application
compiled against OpenSSL, could cause the application to crash.
(CVE-2016-0705)

An integer overflow flaw, leading to a NULL pointer dereference or a
heap-based memory corruption, was found in the way some BIGNUM functions of
OpenSSL were implemented. Applications that use these functions with large
untrusted 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 original
reporters 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 Aviv
University), Nadia Heninger (University of Pennsylvania) as the original
reporters of CVE-2016-0702; and Guido Vranken as the original reporter of
CVE-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.