RHSA-2016:0302 - Security Advisory

Topic

Updated openssl packages that fix three security issues are now available
for Red Hat Enterprise Linux 5

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.

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. It is possible to re-enable the SSLv2 protocol in the
'SSLv23' connection methods by default by setting the OPENSSL_ENABLE_SSL2
environment variable before starting an application that needs to have
SSLv2 enabled. 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)

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; 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.

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

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 1301846 - CVE-2015-3197 OpenSSL: SSLv2 doesn't block disabled ciphers
• BZ - 1310593 - CVE-2016-0800 SSL/TLS: Cross-protocol attack on TLS using SSLv2 (DROWN)
• BZ - 1311880 - CVE-2016-0797 OpenSSL: BN_hex2bn/BN_dec2bn NULL pointer deref/heap corruption

CVEs

• CVE-2016-0797
• CVE-2016-0800
• CVE-2015-3197

References

• https://access.redhat.com/security/updates/classification/#important
• https://access.redhat.com/articles/2176731
• https://drownattack.com/
• https://openssl.org/news/secadv/20160128.txt
• https://openssl.org/news/secadv/20160301.txt