RHEL 5 : openssl (RHSA-2015:1197) (Logjam)
Medium Nessus Plugin ID 84467
SynopsisThe remote Red Hat host is missing one or more security updates.
DescriptionUpdated 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 Moderate 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.
An out-of-bounds read flaw was found in the X509_cmp_time() function of OpenSSL. A specially crafted X.509 certificate or a Certificate Revocation List (CRL) could possibly cause a TLS/SSL server or client using OpenSSL to crash. (CVE-2015-1789)
A NULL pointer dereference was found in the way OpenSSL handled certain PKCS#7 inputs. A specially crafted PKCS#7 input with missing EncryptedContent data could cause an application using OpenSSL to crash. (CVE-2015-1790)
A flaw was found in the way the TLS protocol composes the Diffie-Hellman (DH) key exchange. A man-in-the-middle attacker could use this flaw to force the use of weak 512 bit export-grade keys during the key exchange, allowing them to decrypt all traffic.
Note: This update forces the TLS/SSL client implementation in OpenSSL to reject DH key sizes below 768 bits, which prevents sessions to be downgraded to export-grade keys. Future updates may raise this limit to 1024 bits.
Red Hat would like to thank the OpenSSL project for reporting CVE-2015-1789 and CVE-2015-1790. Upstream acknowledges Robert Swiecki and Hanno Bock as the original reporters of CVE-2015-1789, and Michal Zalewski as the original reporter of CVE-2015-1790.
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.