Updating openssl due to security scan
This bug, if present in the server, makes the DROWN attack run in just a few minutes on, well, our laptops.This reduced complexity could lead to successful real-time man-in-the-middle attacks, hijacking a session even if the client and the server would otherwise negotiate a forward-secure Diffie-Hellman ciphersuite.Much to our surprise, DROWN scans found over 4 million HTTPS servers that, almost a year later, are still unpatched.In the wake of Heartbleed, the world saw a surge of upgrades but the awareness appears to have dropped.Nevertheless, in addition to ensuring that your Postfix configuration disables SSLv2 and weak or obsolete ciphers, you should also deploy the appropriate Open SSL upgrade.Note that if you’re running anything but the latest Open SSL releases from January 2016 (1.0.2f and 1.0.1r), a subtle bug (CVE-2015-3197) allows the server to accept SSLv2 EXPORT handshakes even if EXPORT ciphers are not configured.The below recommended TLS settings for Postfix are sufficient to avoid exposure to DROWN.
The researchers spent a mere US0 on the EC2 cloud platform to decrypt a victim client session in a matter of hours.
Today, an international group of researchers unveiled DROWN (Decrypting RSA with Obsolete and Weakened e Ncryption), aka CVE-2016-0800, a novel cross-protocol attack that uses SSLv2 handshakes to decrypt TLS sessions.
Over the past weeks, the Open SSL team worked closely with the researchers to determine the exact impact of DROWN on Open SSL and devise countermeasures to protect our users.
While 11% of HTTPS servers with browser-trusted certificates are directly vulnerable to DROWN, another whopping 11% fall victim through some other service (most commonly SMTP on port 25).
Second, in the Open SSL security releases of March 2015, we rewrote a section of code, which coincidentally fixed a security bug (CVE-2016-0703).