CVE-2015-0204

La función ssl3_get_key_exchange en s3_clnt.c en OpenSSL en versiones anteriores a 0.9.8zd, 1.0.0 en versiones anteriores a 1.0.0p y 1.0.1 en versiones anteriores a 1.0.1k permite a servidores SSL remotos llevar a cabo ataques de degradación de versión RSA-a-EXPORT_RSA y facilitar el descifrado de fuerza bruta ofreciendo una clave RSA efímera débil en un rol no sumiso, relacionado con el caso "FREAK" . NOTA: el alcance de esta CVE es solo código cliente basado en OpenSSL, no un problema de EXPORT_RSA asociado con servidores u otras implementaciones TLS.

It was discovered that OpenSSL would accept ephemeral RSA keys when using non-export RSA cipher suites. A malicious server could make a TLS/SSL client using OpenSSL use a weaker key exchange method.

A carefully crafted DTLS message can cause a segmentation fault in OpenSSL due to a NULL pointer dereference. A memory leak can occur in the dtls1_buffer_record function under certain conditions. When OpenSSL is built with the no-ssl3 option and a SSL v3 ClientHello is received the ssl method would be set to NULL which could later result in a NULL pointer dereference. An OpenSSL client will accept a handshake using an ephemeral ECDH ciphersuite using an ECDSA certificate if the server key exchange message is omitted. An OpenSSL client will accept the use of an RSA temporary key in a non-export RSA key exchange ciphersuite. An OpenSSL server will accept a DH certificate for client authentication without the certificate verify message. OpenSSL accepts several non-DER-variations of certificate signature algorithm and signature encodings. OpenSSL also does not enforce a match between the signature algorithm between the signed and unsigned portions of the certificate. Bignum squaring (BN_sqr) may produce incorrect results on some platforms, including x86_64.