RHEL 6 : openssl (RHSA-2016:0303) (DROWN)
Medium Nessus Plugin ID 89069
SynopsisThe remote Red Hat host is missing one or more security updates.
DescriptionUpdated openssl packages that fix multiple security issues are now available for Red Hat Enterprise Linux 6.2, 6.4, and 6.5 Advanced Update Support.
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.
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.
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.
It was discovered that the SSLv2 servers using OpenSSL accepted SSLv2 connection handshakes that indicated non-zero clear key length for non-export cipher suites. An attacker could use this flaw to decrypt recorded SSLv2 sessions with the server by using it as a decryption oracle.(CVE-2016-0703)
It was discovered that the SSLv2 protocol implementation in OpenSSL did not properly implement the Bleichenbacher protection for export cipher suites. An attacker could use a SSLv2 server using OpenSSL as a Bleichenbacher oracle. (CVE-2016-0704)
Note: The CVE-2016-0703 and CVE-2016-0704 issues could allow for more efficient exploitation of the CVE-2016-0800 issue via the DROWN attack.
A denial of service flaw was found in the way OpenSSL handled SSLv2 handshake messages. A remote attacker could use this flaw to cause a TLS/SSL server using OpenSSL to exit on a failed assertion if it had both the SSLv2 protocol and EXPORT-grade cipher suites enabled.
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)
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; David Adrian (University of Michigan) and J. Alex Halderman (University of Michigan) as the original reporters of CVE-2016-0703 and CVE-2016-0704; and Sean Burford (Google) and Emilia Kasper (OpenSSL development team) as the original reporters of CVE-2015-0293.
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.
SolutionUpdate the affected packages.