SUSE SLED12 / SLES12 Security Update : openssl (SUSE-SU-2016:0617-1) (DROWN)

This script is Copyright (C) 2016 Tenable Network Security, Inc.


Synopsis :

The remote SUSE host is missing one or more security updates.

Description :

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.

See also :

https://bugzilla.suse.com/952871
https://bugzilla.suse.com/958501
https://bugzilla.suse.com/963415
https://bugzilla.suse.com/968046
https://bugzilla.suse.com/968047
https://bugzilla.suse.com/968048
https://bugzilla.suse.com/968050
https://bugzilla.suse.com/968051
https://bugzilla.suse.com/968053
https://bugzilla.suse.com/968265
https://bugzilla.suse.com/968374
https://www.suse.com/security/cve/CVE-2015-3197.html
https://www.suse.com/security/cve/CVE-2016-0702.html
https://www.suse.com/security/cve/CVE-2016-0703.html
https://www.suse.com/security/cve/CVE-2016-0704.html
https://www.suse.com/security/cve/CVE-2016-0705.html
https://www.suse.com/security/cve/CVE-2016-0797.html
https://www.suse.com/security/cve/CVE-2016-0798.html
https://www.suse.com/security/cve/CVE-2016-0799.html
https://www.suse.com/security/cve/CVE-2016-0800.html
http://www.nessus.org/u?9ee18e5c

Solution :

To install this SUSE Security Update use YaST online_update.
Alternatively you can run the command listed for your product :

SUSE Linux Enterprise Software Development Kit 12 :

zypper in -t patch SUSE-SLE-SDK-12-2016-352=1

SUSE Linux Enterprise Server 12 :

zypper in -t patch SUSE-SLE-SERVER-12-2016-352=1

SUSE Linux Enterprise Desktop 12 :

zypper in -t patch SUSE-SLE-DESKTOP-12-2016-352=1

To bring your system up-to-date, use 'zypper patch'.

Risk factor :

Critical / CVSS Base Score : 10.0
(CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C)
CVSS Temporal Score : 7.4
(CVSS2#E:U/RL:OF/RC:C)
Public Exploit Available : false

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