Updated openssl packages that fix three security issues are now available for Red Hat Enterprise Linux 5

Red Hat Product Security has rated this update as having Important security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols, as well as a full-strength, general purpose cryptography library.

A padding oracle flaw was found in the Secure Sockets Layer version 2.0 (SSLv2) protocol. An attacker can potentially use this flaw to decrypt RSA-encrypted cipher text from a connection using a newer SSL/TLS protocol version, allowing them to decrypt such connections.
This cross-protocol attack is publicly referred to as DROWN.
(CVE-2016-0800)

Note: This issue was addressed by disabling the SSLv2 protocol by default when using the 'SSLv23' connection methods, and removing support for weak SSLv2 cipher suites. It is possible to re-enable the SSLv2 protocol in the 'SSLv23' connection methods by default by setting the OPENSSL_ENABLE_SSL2 environment variable before starting an application that needs to have SSLv2 enabled. For more information, refer to the knowledge base article linked to in the References section.

A flaw was found in the way malicious SSLv2 clients could negotiate SSLv2 ciphers that have been disabled on the server. This could result in weak SSLv2 ciphers being used for SSLv2 connections, making them vulnerable to man-in-the-middle attacks. (CVE-2015-3197)

An integer overflow flaw, leading to a NULL pointer dereference or a heap-based memory corruption, was found in the way some BIGNUM functions of OpenSSL were implemented. Applications that use these functions with large untrusted input could crash or, potentially, execute arbitrary code. (CVE-2016-0797)

Red Hat would like to thank the OpenSSL project for reporting these issues. Upstream acknowledges Nimrod Aviram and Sebastian Schinzel as the original reporters of CVE-2016-0800 and CVE-2015-3197; and Guido Vranken as the original reporter of CVE-2016-0797.

All openssl users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted.

This update for openssl fixes various security issues and bugs :

Security issues fixed :

  - CVE-2016-0800 aka the 'DROWN' attack (bsc#968046):
    OpenSSL was vulnerable to a cross-protocol attack that     could lead to decryption of TLS sessions by using a     server supporting SSLv2 and EXPORT cipher suites as a     Bleichenbacher RSA padding oracle.

    This update changes the openssl library to :

  - Disable SSLv2 protocol support by default.

    This can be overridden by setting the environment     variable 'OPENSSL_ALLOW_SSL2' or by using     SSL_CTX_clear_options using the SSL_OP_NO_SSLv2 flag.

    Note that various services and clients had already     disabled SSL protocol 2 by default previously.

  - Disable all weak EXPORT ciphers by default. These can be     reenabled if required by old legacy software using the     environment variable 'OPENSSL_ALLOW_EXPORT'.

  - CVE-2016-0702 aka the 'CacheBleed' attack. (bsc#968050)     Various changes in the modular exponentation code were     added that make sure that it is not possible to recover     RSA secret keys by analyzing cache-bank conflicts on the     Intel Sandy-Bridge microarchitecture.

    Note that this was only exploitable if the malicious     code was running on the same hyper threaded Intel Sandy     Bridge processor as the victim thread performing     decryptions.

  - CVE-2016-0705 (bnc#968047): A double free() bug in the     DSA ASN1 parser code was fixed that could be abused to     facilitate a denial-of-service attack.

  - CVE-2016-0797 (bnc#968048): The BN_hex2bn() and     BN_dec2bn() functions had a bug that could result in an     attempt to de-reference a NULL pointer leading to     crashes. This could have security consequences if these     functions were ever called by user applications with     large untrusted hex/decimal data. Also, internal usage     of these functions in OpenSSL uses data from config     files or application command line arguments. If user     developed applications generated config file data based     on untrusted data, then this could have had security     consequences as well.

  - CVE-2016-0798 (bnc#968265) The SRP user database lookup     method SRP_VBASE_get_by_user() had a memory leak that     attackers could abuse to facility DoS attacks. To     mitigate the issue, the seed handling in     SRP_VBASE_get_by_user() was disabled even if the user     has configured a seed. Applications are advised to     migrate to SRP_VBASE_get1_by_user().

  - CVE-2016-0799 (bnc#968374) On many 64 bit systems, the     internal fmtstr() and doapr_outch() functions could     miscalculate the length of a string and attempt to     access out-of-bounds memory locations. These problems     could have enabled attacks where large amounts of     untrusted data is passed to the BIO_*printf functions.
    If applications use these functions in this way then     they could have been vulnerable. OpenSSL itself uses     these functions when printing out human-readable dumps     of ASN.1 data. Therefore applications that print this     data could have been vulnerable if the data is from     untrusted sources. OpenSSL command line applications     could also have been vulnerable when they print out     ASN.1 data, or if untrusted data is passed as command     line arguments. Libssl is not considered directly     vulnerable.

  - CVE-2015-3197 (bsc#963415): The SSLv2 protocol did not     block disabled ciphers.

Note that the March 1st 2016 release also references following CVEs that were fixed by us with CVE-2015-0293 in 2015 :

  - CVE-2016-0703 (bsc#968051): This issue only affected     versions of OpenSSL prior to March 19th 2015 at which     time the code was refactored to address vulnerability     CVE-2015-0293. It would have made the above 'DROWN'     attack much easier.

  - CVE-2016-0704 (bsc#968053): 'Bleichenbacher oracle in     SSLv2' This issue only affected versions of OpenSSL     prior to March 19th 2015 at which time the code was     refactored to address vulnerability CVE-2015-0293. It     would have made the above 'DROWN' attack much easier.

Bugs fixed :

  - Avoid running OPENSSL_config twice. This avoids breaking     engine loading. (bsc#952871)

  - Ensure that OpenSSL doesn't fall back to the default     digest algorithm (SHA1) in case a non-FIPS algorithm was     negotiated while running in FIPS mode. Instead, OpenSSL     will refuse the digest. (bnc#958501)

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

A denial of service flaw was found in the way OpenSSL handled SSLv2 handshake messages. A remote attacker could use this flaw to cause a TLS/SSL server using OpenSSL to exit on a failed assertion if it had both the SSLv2 protocol and EXPORT-grade cipher suites enabled.
(CVE-2015-0293)

It was discovered that the SSLv2 servers using OpenSSL accepted SSLv2 connection handshakes that indicated non-zero clear key length for non-export cipher suites. An attacker could use this flaw to decrypt recorded SSLv2 sessions with the server by using it as a decryption oracle. (CVE-2016-0703)

It was discovered that the SSLv2 protocol implementation in OpenSSL did not properly implement the Bleichenbacher protection for export cipher suites. An attacker could use a SSLv2 server using OpenSSL as a Bleichenbacher oracle. (CVE-2016-0704)

A padding oracle flaw was found in the Secure Sockets Layer version 2.0 (SSLv2) protocol. An attacker can potentially use this flaw to decrypt RSA-encrypted cipher text from a connection using a newer SSL/TLS protocol version, allowing them to decrypt such connections.
This cross-protocol attack is publicly referred to as DROWN.
(CVE-2016-0800)

A flaw was found in the way malicious SSLv2 clients could negotiate SSLv2 ciphers that have been disabled on the server. This could result in weak SSLv2 ciphers being used for SSLv2 connections, making them vulnerable to man-in-the-middle attacks. (CVE-2015-3197)

According to its banner, the version of OpenSSL on the remote host is 1.0.2 prior to 1.0.2f or 1.0.1 prior to 1.0.1r and is affected by a flaw that is triggered when handling cipher negotiation. This may allow a remote attacker to negotiate SSLv2 ciphers that are disabled on the server.

ID	Name	Product	Family	Published	Updated	Severity
89068	RHEL 5 : openssl (RHSA-2016:0302) (DROWN)	Nessus	Red Hat Local Security Checks	3/2/2016	10/24/2019	high
89076	SUSE SLED12 / SLES12 Security Update : openssl (SUSE-SU-2016:0617-1) (DROWN)	Nessus	SuSE Local Security Checks	3/2/2016	1/6/2021	critical
90364	Amazon Linux AMI : openssl098e (ALAS-2016-682) (DROWN)	Nessus	Amazon Linux Local Security Checks	4/7/2016	4/18/2018	medium
89060	CentOS 5 : openssl (CESA-2016:0302) (DROWN)	Nessus	CentOS Local Security Checks	3/2/2016	1/4/2021	high
9464	OpenSSL 1.0.1 < 1.0.1r / 1.0.2 < 1.0.2f Information Disclosure	Nessus Network Monitor	Web Servers	8/5/2016	3/6/2019	low

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