10 - RHSA-2016:0301

Problem Description:

Updated openssl packages that fix multiple security issues are now available for Red Hat Enterprise Linux 6 and 7.

Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Client (v. 7) - x86_64 Red Hat Enterprise Linux Client Optional (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode (v. 7) - x86_64 Red Hat Enterprise Linux ComputeNode Optional (v. 7) - x86_64 Red Hat Enterprise Linux Desktop (v. 6) - i386, x86_64 Red Hat Enterprise Linux Desktop Optional (v. 6) - i386, x86_64 Red Hat Enterprise Linux HPC Node (v. 6) - x86_64 Red Hat Enterprise Linux HPC Node Optional (v. 6) - x86_64 Red Hat Enterprise Linux Server (v. 6) - i386, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server (v. 7) - ppc64, ppc64le, s390x, x86_64 Red Hat Enterprise Linux Server Optional (v. 6) - i386, ppc64, s390x, x86_64 Red Hat Enterprise Linux Server Optional (v. 7) - ppc64, ppc64le, s390x, x86_64 Red Hat Enterprise Linux Workstation (v. 6) - i386, x86_64 Red Hat Enterprise Linux Workstation (v. 7) - x86_64 Red Hat Enterprise Linux Workstation Optional (v. 6) - i386, x86_64 Red Hat Enterprise Linux Workstation Optional (v. 7) - x86_64

3. Description:

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.

4. Solution:

Before applying this update, make sure all previously released errata relevant to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258

5. Bugs fixed (https://bugzilla.redhat.com/):

1301846 - CVE-2015-3197 OpenSSL: SSLv2 doesn't block disabled ciphers 1310593 - CVE-2016-0800 SSL/TLS: Cross-protocol attack on TLS using SSLv2 (DROWN) 1310596 - CVE-2016-0705 OpenSSL: Double-free in DSA code 1310599 - CVE-2016-0702 OpenSSL: Side channel attack on modular exponentiation 1311880 - CVE-2016-0797 OpenSSL: BN_hex2bn/BN_dec2bn NULL pointer deref/heap corruption