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Poodle (CVE-2014-3566) Attack and Mitigation Details from PLXsert

Akamai's Prolexic Security Engineering & Research Team (PLXsert) issued a new advisory Monday that provides a full analysis of the Poodle vulnerability, including actions companies can take to blunt the impact.

It's the latest in a series of postings Akamai has done to keep the public informed of its Poodle response. In addition to reviewing this new advisory, please refer to the following posts as well:

This is the latest in a string of severe vulnerabilities this year, including Shellshock and Heartbleed. A full list of resources for all of these incidents can be found here.

The PLXsert Poodle advisory, available on Akamai's new State of the Internet website, describes the problem this way:

A newly disclosed vulnerability in Secure Socket Layer version 3 (SSLv3) CVE-2014-35661 may allow an attacker to calculate the plaintext (cleartext) in secure connections, effectively defeating SSL protection. The SSL security protocol is designed to protect communications on the Internet by wrapping them with encryption to preserve the confidentiality and integrity of communications. It is often used for banking transactions, shopping, secure messaging, instant messaging and email. The vulnerability affects only SSL version 3. It does not affect newer encryption protocols such as Transport Layer Security (TLS).

A proof-of-concept attack called POODLE (Padding Oracle On Downgraded Legacy Encryption) crafted by Google researchers was provided with the vulnerability disclosure.2 Malicious actors are likely to weaponize and create exploitation tools for the vulnerability. (Please note that the name padding oracle has nothing to do with Oracle Corporation or its products; it refers to the target system as an answer-providing oracle.)

This vulnerability may be exploited via man-in-the-middle attacks where a malicious actor will force the fallback (downgrade) of the encryption protocol to SSLv3 and then target the system decrypting the data (the client), observing the exchange and applying a padding oracle attack3 to recover the plaintext.

The advisory gives a step-by-step example of how attackers could exploit the vulnerability, complete with screen shots and other graphics.

The most important information in the advisory concerns the steps companies can take to protect themselves. Specifically:

  • PLXsert recommends disabling SSLv3 wherever possible. Details are provided in the bulletin.
  • Apply patches and updates from vendors, especially in cases where SSLv3 can't be disabled.
  • Akamai has accelerated its deprecation of SSLv3 and earlier versions.
  • Akamai has deployed support for TLS Signaling Cipher Suite Value (SCSV). SCSV prevents downgrading or fallback attacks to SSLv3 or earlier versions in case of a man-in-the-middle attack.
  • A snort rule provided in the bulletin detects SSLv3 client connection attempts.