CVE-2014-3566

El protocolo SSL 3.0, utilizado en OpenSSL hasta 1.0.1i y otros productos, utiliza relleno (padding) CBC no determinístico, lo que facilita a los atacantes man-in-the-middle obtener datos de texto plano a través de un ataque de relleno (padding) oracle, también conocido como el problema "POODLE".

A flaw was found in the way SSL 3.0 handled padding bytes when decrypting messages encrypted using block ciphers in cipher block chaining (CBC) mode. This flaw allows a man-in-the-middle (MITM) attacker to decrypt a selected byte of a cipher text in as few as 256 tries if they are able to force a victim application to repeatedly send the same data over newly created SSL 3.0 connections.

A flaw in the DTLS SRTP extension parsing code allows an attacker, who sends a carefully crafted handshake message, to cause OpenSSL to fail to free up to 64k of memory causing a memory leak. When an OpenSSL SSL/TLS/DTLS server receives a session ticket the integrity of that ticket is first verified. In the event of a session ticket integrity check failing, OpenSSL will fail to free memory causing a memory leak. The SSL protocol 3.0, as supported in OpenSSL and other products, supports CBC mode encryption where it could not adequately check the integrity of padding, because of the use of non-deterministic CBC padding. This protocol weakness makes it possible for an attacker to obtain clear text data through a padding-oracle attack. Some client applications (such as browsers) will reconnect using a downgraded protocol to work around interoperability bugs in older servers. This could be exploited by an active man-in-the-middle to downgrade connections to SSL 3.0 even if both sides of the connection support higher protocols. SSL 3.0 contains a number of weaknesses including POODLE.