Many modern TLS clients can fall back to version 3.0 of the SSL protocol, which is vulnerable to a padding-oracle attack when Cypher-block chaining (CBC) mode is used. This is commonly referred to as the "POODLE" (Padding Oracle On Downgraded Legacy Encryption) attack.
CWE-327: Use of a Broken or Risky Cryptographic Algorithm - CVE-2014-3566
Multiple implementations of SSL 3.0, including the implementation in OpenSSL up to version 1.0.1i, support the use of CBC mode. However, SSL 3.0 is vulnerable to a padding-oracle attack when CBC mode is used. A successful padding-oracle attack can provide an attacker with cleartext information from the encrypted communications.
An adjacent, unauthenticated attacker may be able to derive cleartext information from communications that utilize the SSL 3.0 protocol with CBC mode.
OpenSSL has fixed the issue in OpenSSL versions 1.0.1j, 1.0.0o, and 0.9.8zc. For other implementations of the protocol, please check with the appropriate maintainer or vendor to determine if the implementation is affected by this issue. Additionally, consider the following workaround:
This document was written by Todd Lewellen.
|Date First Published:||2014-10-17|
|Date Last Updated:||2015-01-21 19:34 UTC|