Not out of the woods yet: There are more POODLEs

As I wrote in my previous article about this, in October a group of Google security researchers had discovered a problem, called POODLE, in SSL v3 that in combination with another issue, browsers’ automatic fallback to older TLS and SSL versions, allowed an attacker to quickly break the encryption of sensitive content, like cookies.

The main mitigating methods for this problem are disabling SSL v3 support, both server side (now down to 66.2%, but slowing down) and in the client, and to limit the automatic fallback, either by not falling back to SSL v3 (which is now implemented by several browsers), or by a new method called TLS_FALLBACK_SCSV (introduced by Google Chrome and others). Continue reading “Not out of the woods yet: There are more POODLEs”

Attack of the POODLEs

Three weeks ago a group of researchers from Google announced an attack against the SSL v3 protocol (the ancestor of the TLS 1.x protocol) called POODLE (a stylish abbreviation of “Padding Oracle On Downgraded Legacy Encryption”). This attack is similar to the BEAST¬†attack that was revealed a few years ago, and one of the researchers that found the POODLE attack was part of the team that found BEAST.

POODLE is able to quickly discover the content of a HTTPS request, such as a session cookie, but only if the connection is using the SSL v3 protocol, a version of SSL/TLS that became obsolete with the introduction of TLS 1.0 in 1999. As almost all (>99%) secure web servers now support at least TLS 1.0 (which is not vulnerable to the attack, provided the server is correctly implemented), it might sound like this attack is not very useful. Unfortunately, that is not so. Continue reading “Attack of the POODLEs”