OpenSSL Updates Fix TLS Denial-of-Service and x86_64 Cryptographic Flaws

OpenSSL released updates 1.1.0d and 1.0.2k to address several Moderate-severity defects, including CVE-2017-3731, an integer-underflow out-of-bounds read that lets specially truncated TLS packets crash affected 32-bit clients or servers using vulnerable cipher suites such as RC4-MD5. The releases also addressed CVE-2017-3730, in which malicious DHE or ECDHE parameters can trigger a NULL-pointer dereference in clients, and CVE-2017-3732, a carry-propagation flaw in x86_64 Montgomery squaring that can yield incorrect cryptographic results. Exploiting the latter against RSA or DSA is considered highly impractical; a Diffie-Hellman attack is more feasible only under restrictive conditions involving unpatched systems, persistent shared DH parameters, and substantial resources.

Red Hat shipped updated OpenSSL packages for RHEL 6 and 7 through RHSA-2017:0286, remediating CVE-2017-3731 and CVE-2016-8610. The latter allows unauthenticated attackers to send large volumes of malformed plaintext TLS/SSL ALERT messages during handshakes, consuming server CPU and preventing new connections; Nginx deployments were identified as affected, while Apache HTTP Server was not. Organizations should apply the vendor updates, restart all services linked to OpenSSL or reboot hosts, disable RC4-MD5 where updates cannot be immediately deployed, and retire unsupported OpenSSL 1.0.1, 1.0.0, and 0.9.8 installations.