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OpenSSL CHANGES
_______________
+ Changes between 1.0.1t and 1.0.1u [22 Sep 2016]
+
+ *) OCSP Status Request extension unbounded memory growth
+
+ A malicious client can send an excessively large OCSP Status Request
+ extension. If that client continually requests renegotiation, sending a
+ large OCSP Status Request extension each time, then there will be unbounded
+ memory growth on the server. This will eventually lead to a Denial Of
+ Service attack through memory exhaustion. Servers with a default
+ configuration are vulnerable even if they do not support OCSP. Builds using
+ the "no-ocsp" build time option are not affected.
+
+ This issue was reported to OpenSSL by Shi Lei (Gear Team, Qihoo 360 Inc.)
+ (CVE-2016-6304)
+ [Matt Caswell]
+
+ *) In order to mitigate the SWEET32 attack, the DES ciphers were moved from
+ HIGH to MEDIUM.
+
+ This issue was reported to OpenSSL Karthikeyan Bhargavan and Gaetan
+ Leurent (INRIA)
+ (CVE-2016-2183)
+ [Rich Salz]
+
+ *) OOB write in MDC2_Update()
+
+ An overflow can occur in MDC2_Update() either if called directly or
+ through the EVP_DigestUpdate() function using MDC2. If an attacker
+ is able to supply very large amounts of input data after a previous
+ call to EVP_EncryptUpdate() with a partial block then a length check
+ can overflow resulting in a heap corruption.
+
+ The amount of data needed is comparable to SIZE_MAX which is impractical
+ on most platforms.
+
+ This issue was reported to OpenSSL by Shi Lei (Gear Team, Qihoo 360 Inc.)
+ (CVE-2016-6303)
+ [Stephen Henson]
+
+ *) Malformed SHA512 ticket DoS
+
+ If a server uses SHA512 for TLS session ticket HMAC it is vulnerable to a
+ DoS attack where a malformed ticket will result in an OOB read which will
+ ultimately crash.
+
+ The use of SHA512 in TLS session tickets is comparatively rare as it requires
+ a custom server callback and ticket lookup mechanism.
+
+ This issue was reported to OpenSSL by Shi Lei (Gear Team, Qihoo 360 Inc.)
+ (CVE-2016-6302)
+ [Stephen Henson]
+
+ *) OOB write in BN_bn2dec()
+
+ The function BN_bn2dec() does not check the return value of BN_div_word().
+ This can cause an OOB write if an application uses this function with an
+ overly large BIGNUM. This could be a problem if an overly large certificate
+ or CRL is printed out from an untrusted source. TLS is not affected because
+ record limits will reject an oversized certificate before it is parsed.
+
+ This issue was reported to OpenSSL by Shi Lei (Gear Team, Qihoo 360 Inc.)
+ (CVE-2016-2182)
+ [Stephen Henson]
+
+ *) OOB read in TS_OBJ_print_bio()
+
+ The function TS_OBJ_print_bio() misuses OBJ_obj2txt(): the return value is
+ the total length the OID text representation would use and not the amount
+ of data written. This will result in OOB reads when large OIDs are
+ presented.
+
+ This issue was reported to OpenSSL by Shi Lei (Gear Team, Qihoo 360 Inc.)
+ (CVE-2016-2180)
+ [Stephen Henson]
+
+ *) Pointer arithmetic undefined behaviour
+
+ Avoid some undefined pointer arithmetic
+
+ A common idiom in the codebase is to check limits in the following manner:
+ "p + len > limit"
+
+ Where "p" points to some malloc'd data of SIZE bytes and
+ limit == p + SIZE
+
+ "len" here could be from some externally supplied data (e.g. from a TLS
+ message).
+
+ The rules of C pointer arithmetic are such that "p + len" is only well
+ defined where len <= SIZE. Therefore the above idiom is actually
+ undefined behaviour.
+
+ For example this could cause problems if some malloc implementation
+ provides an address for "p" such that "p + len" actually overflows for
+ values of len that are too big and therefore p + len < limit.
+
+ This issue was reported to OpenSSL by Guido Vranken
+ (CVE-2016-2177)
+ [Matt Caswell]
+
+ *) Constant time flag not preserved in DSA signing
+
+ Operations in the DSA signing algorithm should run in constant time in
+ order to avoid side channel attacks. A flaw in the OpenSSL DSA
+ implementation means that a non-constant time codepath is followed for
+ certain operations. This has been demonstrated through a cache-timing
+ attack to be sufficient for an attacker to recover the private DSA key.
+
+ This issue was reported by César Pereida (Aalto University), Billy Brumley
+ (Tampere University of Technology), and Yuval Yarom (The University of
+ Adelaide and NICTA).
+ (CVE-2016-2178)
+ [César Pereida]
+
+ *) DTLS buffered message DoS
+
+ In a DTLS connection where handshake messages are delivered out-of-order
+ those messages that OpenSSL is not yet ready to process will be buffered
+ for later use. Under certain circumstances, a flaw in the logic means that
+ those messages do not get removed from the buffer even though the handshake
+ has been completed. An attacker could force up to approx. 15 messages to
+ remain in the buffer when they are no longer required. These messages will
+ be cleared when the DTLS connection is closed. The default maximum size for
+ a message is 100k. Therefore the attacker could force an additional 1500k
+ to be consumed per connection. By opening many simulataneous connections an
+ attacker could cause a DoS attack through memory exhaustion.
+
+ This issue was reported to OpenSSL by Quan Luo.
+ (CVE-2016-2179)
+ [Matt Caswell]
+
+ *) DTLS replay protection DoS
+
+ A flaw in the DTLS replay attack protection mechanism means that records
+ that arrive for future epochs update the replay protection "window" before
+ the MAC for the record has been validated. This could be exploited by an
+ attacker by sending a record for the next epoch (which does not have to
+ decrypt or have a valid MAC), with a very large sequence number. This means
+ that all subsequent legitimate packets are dropped causing a denial of
+ service for a specific DTLS connection.
+
+ This issue was reported to OpenSSL by the OCAP audit team.
+ (CVE-2016-2181)
+ [Matt Caswell]
+
+ *) Certificate message OOB reads
+
+ In OpenSSL 1.0.2 and earlier some missing message length checks can result
+ in OOB reads of up to 2 bytes beyond an allocated buffer. There is a
+ theoretical DoS risk but this has not been observed in practice on common
+ platforms.
+
+ The messages affected are client certificate, client certificate request
+ and server certificate. As a result the attack can only be performed
+ against a client or a server which enables client authentication.
+
+ This issue was reported to OpenSSL by Shi Lei (Gear Team, Qihoo 360 Inc.)
+ (CVE-2016-6306)
+ [Stephen Henson]
+
Changes between 1.0.1s and 1.0.1t [3 May 2016]
*) Prevent padding oracle in AES-NI CBC MAC check