FreeBSD : FreeBSD -- Multiple OpenSSL vulnerabilities (7b1a4a27-600a-11e6-a6c3-14dae9d210b8) (DROWN)
Critical Nessus Plugin ID 92921
SynopsisThe remote FreeBSD host is missing one or more security-related updates.
DescriptionA cross-protocol attack was discovered that could lead to decryption of TLS sessions by using a server supporting SSLv2 and EXPORT cipher suites as a Bleichenbacher RSA padding oracle. Note that traffic between clients and non-vulnerable servers can be decrypted provided another server supporting SSLv2 and EXPORT ciphers (even with a different protocol such as SMTP, IMAP or POP3) shares the RSA keys of the non-vulnerable server. This vulnerability is known as DROWN.
A double free bug was discovered when OpenSSL parses malformed DSA private keys and could lead to a DoS attack or memory corruption for applications that receive DSA private keys from untrusted sources.
This scenario is considered rare. [CVE-2016-0705]
The SRP user database lookup method SRP_VBASE_get_by_user had confusing memory management semantics; the returned pointer was sometimes newly allocated, and sometimes owned by the callee. The calling code has no way of distinguishing these two cases.
In the BN_hex2bn function, the number of hex digits is calculated using an int value |i|. Later |bn_expand| is called with a value of |i
* 4|. For large values of |i| this can result in |bn_expand| not allocating any memory because |i * 4| is negative. This can leave the internal BIGNUM data field as NULL leading to a subsequent NULL pointer dereference. For very large values of |i|, the calculation |i
* 4| could be a positive value smaller than |i|. In this case memory is allocated to the internal BIGNUM data field, but it is insufficiently sized leading to heap corruption. A similar issue exists in BN_dec2bn. This could have security consequences if BN_hex2bn/BN_dec2bn is ever called by user applications with very large untrusted hex/dec data. This is anticipated to be a rare occurrence. [CVE-2016-0797]
The internal |fmtstr| function used in processing a '%s' formatted string in the BIO_*printf functions could overflow while calculating the length of a string and cause an out-of-bounds read when printing very long strings. [CVE-2016-0799]
A side-channel attack was found which makes use of cache-bank conflicts on the Intel Sandy-Bridge microarchitecture which could lead to the recovery of RSA keys. [CVE-2016-0702]
s2_srvr.c did not enforce that clear-key-length is 0 for non-export ciphers. If clear-key bytes are present for these ciphers, they displace encrypted-key bytes. [CVE-2016-0703]
s2_srvr.c overwrites the wrong bytes in the master key when applying Bleichenbacher protection for export cipher suites. [CVE-2016-0704] Impact : Servers that have SSLv2 protocol enabled are vulnerable to the 'DROWN' attack which allows a remote attacker to fast attack many recorded TLS connections made to the server, even when the client did not make any SSLv2 connections themselves.
An attacker who can supply malformed DSA private keys to OpenSSL applications may be able to cause memory corruption which would lead to a Denial of Service condition. [CVE-2016-0705]
An attacker connecting with an invalid username can cause memory leak, which could eventually lead to a Denial of Service condition.
An attacker who can inject malformed data into an application may be able to cause memory corruption which would lead to a Denial of Service condition. [CVE-2016-0797, CVE-2016-0799]
A local attacker who has control of code in a thread running on the same hyper-threaded core as the victim thread which is performing decryptions could recover RSA keys. [CVE-2016-0702]
An eavesdropper who can intercept SSLv2 handshake can conduct an efficient divide-and-conquer key recovery attack and use the server as an oracle to determine the SSLv2 master-key, using only 16 connections to the server and negligible computation. [CVE-2016-0703]
An attacker can use the Bleichenbacher oracle, which enables more efficient variant of the DROWN attack. [CVE-2016-0704]
SolutionUpdate the affected packages.