With help from the Linux Foundation’s Core Infrastructure Initiative (CII) and the NCC Group, the OpenSSL project has patched a number of moderate- and low-level security vulnerabilities in the latest releases of its software.
The majority of the fixes are related to moderate-severity denial-of-service bugs. Notably, the revised software also protects against a vulnerability in the TLS protocol called Logjam that gained notoriety last month.
As Malwarebytes explains, Logjam was discovered by a group of security researchers and computer scientists. It affects how a Diffie-Hellman (DH) key exchange is deployed on the web which is used to establish session keys between two communicating party.
Specifically, it is a man-in-the-middle attack that’s capable of downgrading a connection to 512-bit export-grade encryption. It isn’t all that different from the FREAK flaw except that, as researchers note, it applies to the Diffie-Hellman ciphersuites and is a TLS protocol flaw rather than an implementation vulnerability.
512-bit encryption was at one time considered quite strong. But as computing power has evolved, it’s now possible to crack such a key in a matter of hours using Amazon Web services at a cost of around $100.
The latest version of OpenSSL will reject handshakes with DH parameters shorter than 768 bits, a limit that will be increased to 1,024 bits in a future release.
Those running OpenSSL 1.0.2 are advised to upgrade to 1.0.2b while those using OpenSSL 1.0.1 should upgrade to version 1.0.1n.