The SWEET32 issue, CVE-2016-2183

Today, Karthik Bhargavan and Gaetan Leurent from Inria have unveiled a new attack on Triple-DES, SWEET32, Birthday attacks on 64-bit block ciphers in TLS and OpenVPN. It has been assigned CVE-2016-2183.

This post gives a bit of background and describes what OpenSSL is doing. For more details, see their website.

An OpenSSL user's guide to DROWN

Today, an international group of researchers unveiled DROWN (Decrypting RSA with Obsolete and Weakened eNcryption), aka CVE-2016-0800, a novel cross-protocol attack that uses SSLv2 handshakes to decrypt TLS sessions.

Over the past weeks, the OpenSSL team worked closely with the researchers to determine the exact impact of DROWN on OpenSSL and devise countermeasures to protect our users. Today’s OpenSSL release makes it impossible to configure a TLS server in such a way that it is vulnerable to DROWN.

New severity level, "Critical"

We’ve just added a new severity level called “critical severity” to our security policy. When we first introduced the policy, over a year ago, we just had three levels, “Low”, “Moderate”, and “High”. So why did we add “Critical” and why are we not using someone else’s standard definitions? After introducing the new policy we started giving everyone a headsup when we were due to release OpenSSL updates that included security fixes.

OpenSSL Security: A Year in Review

Over the last 10 years, OpenSSL has published advisories on over 100 vulnerabilities. Many more were likely silently fixed in the early days, but in the past year our goal has been to establish a clear public record. In September 2014, the team adopted a security policy that defines how we handle vulnerability reports. One year later, I’m very happy to conclude that our policy is enforced, and working well.

Logjam, FREAK and upcoming changes in OpenSSL

Today, news broke of Logjam, an attack on TLS connections using Diffie-Hellman ciphersuites. To protect OpenSSL-based clients, we’re increasing the minimum accepted DH key size to 768 bits immediately in the next release, and to 1024 bits soon after. We have also made several other changes to strengthen our cryptographic defaults and have updated our tools and documentation to help servers configure Diffie-Hellman ciphersuites securely - see below for details.

Security Updates

We’ve just released security updates to OpenSSL 0.9.8, 1.0.0, 1.0.1, and 1.0.2.

These updates fix a number of Moderate and Low severity security issues in OpenSSL. They also fix one new High severity issue, CVE-2015-0291, that affects just OpenSSL 1.0.2, released in January this year. A remote attacker could use this flaw to cause unfixed servers to crash, which could lead to a denial of service attack depending on the server.