There are more POODLEs in the forest

In December it was announced that several TLS server implementations were affected by a problem similar to an SSL v3 issue called POODLE disclosed by Google researchers in October. This attack worked by modifying the padding bytes of the encrypted SSL/TLS records that are used to make the records into even multiples of 8 or 16 byte blocks of data, checking how the server responded, and used this to deduce the plain text of the transmitted data, one byte at a time, with just a few tries.

Several major vendors were affected by the TLS variant of the POODLE issue, and released patches. Continue reading «There are more POODLEs in the forest»

The POODLE has friends

In October last year, researchers from Google published details about an attack on SSL v3, called POODLE. This attack worked by modifying the padding bytes of the encrypted SSL records that are used to make the records into even multiples of 8 or 16 byte blocks of data, as used by 3DES and AES encryption in the «CBC» mode, checking how the server responded, and used this to deduce the plain text of the transmitted data, one byte at a time, with just a few tries. Continue reading «The POODLE has friends»

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»