OpenSSL: 8 Bugs Fixed

First off, I’d like to explain what OpenSSL is!

OpenSSL refers to the name of a 1998 project that was started to encrypt websites and user information across the Web. The “SSL” in “OpenSSL” refers to a Secure Sockets Layer (also known as transport layer security or TLS), and OpenSSL is an open project, meaning any programmer or coder can work on it, it was designed to prevent hackers from retrieving personal data submitted by users to a website (such as a banking, shopping, or digital content website). Eric Young is responsible for the eventual establishment of OpenSSL, seeing that he started what ultimately became SSL software back in the 1990s. OpenSSL is an important undertaking, seeing that, without it, our personal information submitted across every website we hold dear could find its way into the hands of dishonest criminals. What started as a project committed to data encryption has now become standard on two-thirds of all websites on the Internet.

According to this advisory from OpenSSL, there are eight security fixes. They address some very technical issues:

1. A carefully crafted DTLS message can cause a segmentation fault in OpenSSL due to a NULL pointer dereference. This could lead to a Denial Of Service attack.
2. A memory leak can occur in the dtls1_buffer_record function under certain conditions. In particular this could occur if an attacker sent repeated DTLS records with the same sequence number but for the next epoch. The memory leak could be exploited by an attacker in a Denial of Service attack through memory exhaustion.
3. 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.
4. An OpenSSL client will accept a handshake using an ephemeral ECDH ciphersuite using an ECDSA certificate if the server key exchange message is omitted. This effectively removes forward secrecy from the ciphersuite.
5. An OpenSSL client will accept the use of an RSA temporary key in a non-export RSA key exchange ciphersuite. A server could present a weak temporary key and downgrade the security of the session.
6. An OpenSSL server will accept a DH certificate for client authentication without the certificate verify message. This effectively allows a client to authenticate without the use of a private key. This only affects servers which trust a client certificate authority which issues certificates containing DH keys: these are extremely rare and hardly ever encountered.
7. OpenSSL accepts several non-DER-variations (DER = Distinguished Encoding Rules) 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. By modifying the contents of the signature algorithm or the encoding of the signature, it is possible to change the certificate’s fingerprint. This does not allow an attacker to forge certificates, and does not affect certificate verification or OpenSSL servers/clients in any other way. It also does not affect common revocation mechanisms. Only custom applications that rely on the uniqueness of the fingerprint (e.g. certificate blacklists) may be affected.
8. Bignum squaring (BN_sqr) may produce incorrect results on some platforms, including x86_64. This bug occurs at random with a very low probability, and is not known to be exploitable in any way, though its exact impact is difficult to determine.