OpenSSL Security Advisory [3 Dec 2015] - Updated [4 Dec 2015]
=============================================================
[Updated 4 Dec 2015]: This advisory has been updated to include the details of
CVE-2015-1794, a Low severity issue affecting OpenSSL 1.0.2 which had a fix
included in the released packages but was missed from the advisory text.
NOTE: WE ANTICIPATE THAT 1.0.0t AND 0.9.8zh WILL BE THE LAST RELEASES FOR THE
0.9.8 AND 1.0.0 VERSIONS AND THAT NO MORE SECURITY FIXES WILL BE PROVIDED (AS
PER PREVIOUS ANNOUNCEMENTS). USERS ARE ADVISED TO UPGRADE TO LATER VERSIONS.
BN_mod_exp may produce incorrect results on x86_64 (CVE-2015-3193)
==================================================================
Severity: Moderate
There is a carry propagating bug in the x86_64 Montgomery squaring procedure. No
EC algorithms are affected. Analysis suggests that attacks against RSA and DSA
as a result of this defect would be very difficult to perform and are not
believed likely. Attacks against DH are considered just feasible (although very
difficult) because most of the work necessary to deduce information
about a private key may be performed offline. The amount of resources
required for such an attack would be very significant and likely only
accessible to a limited number of attackers. An attacker would
additionally need online access to an unpatched system using the target
private key in a scenario with persistent DH parameters and a private
key that is shared between multiple clients. For example this can occur by
default in OpenSSL DHE based SSL/TLS ciphersuites.
This issue affects OpenSSL version 1.0.2.
OpenSSL 1.0.2 users should upgrade to 1.0.2e
This issue was reported to OpenSSL on August 13 2015 by Hanno
Böck. The fix was developed by Andy Polyakov of the OpenSSL
development team.
Certificate verify crash with missing PSS parameter (CVE-2015-3194)
===================================================================
Severity: Moderate
The signature verification routines will crash with a NULL pointer dereference
if presented with an ASN.1 signature using the RSA PSS algorithm and absent
mask generation function parameter. Since these routines are used to verify
certificate signature algorithms this can be used to crash any certificate
verification operation and exploited in a DoS attack. Any application which
performs certificate verification is vulnerable including OpenSSL clients and
servers which enable client authentication.
This issue affects OpenSSL versions 1.0.2 and 1.0.1.
OpenSSL 1.0.2 users should upgrade to 1.0.2e
OpenSSL 1.0.1 users should upgrade to 1.0.1q
This issue was reported to OpenSSL on August 27 2015 by Loïc Jonas Etienne
(Qnective AG). The fix was developed by Dr. Stephen Henson of the OpenSSL
development team.
X509_ATTRIBUTE memory leak (CVE-2015-3195)
==========================================
Severity: Moderate
When presented with a malformed X509_ATTRIBUTE structure OpenSSL will leak
memory. This structure is used by the PKCS#7 and CMS routines so any
application which reads PKCS#7 or CMS data from untrusted sources is affected.
SSL/TLS is not affected.
This issue affects OpenSSL versions 1.0.2 and 1.0.1, 1.0.0 and 0.9.8.
OpenSSL 1.0.2 users should upgrade to 1.0.2e
OpenSSL 1.0.1 users should upgrade to 1.0.1q
OpenSSL 1.0.0 users should upgrade to 1.0.0t
OpenSSL 0.9.8 users should upgrade to 0.9.8zh
This issue was reported to OpenSSL on November 9 2015 by Adam Langley
(Google/BoringSSL) using libFuzzer. The fix was developed by Dr. Stephen
Henson of the OpenSSL development team.
Race condition handling PSK identify hint (CVE-2015-3196)
=========================================================
Severity: Low
If PSK identity hints are received by a multi-threaded client then
the values are wrongly updated in the parent SSL_CTX structure. This can
result in a race condition potentially leading to a double free of the
identify hint data.
This issue was fixed in OpenSSL 1.0.2d and 1.0.1p but has not been previously
listed in an OpenSSL security advisory. This issue also affects OpenSSL 1.0.0
and has not been previously fixed in an OpenSSL 1.0.0 release.
OpenSSL 1.0.2 users should upgrade to 1.0.2d
OpenSSL 1.0.1 users should upgrade to 1.0.1p
OpenSSL 1.0.0 users should upgrade to 1.0.0t
The fix for this issue can be identified in the OpenSSL git repository by commit
ids 3c66a669dfc7 (1.0.2), d6be3124f228 (1.0.1) and 1392c238657e (1.0.0).
The fix was developed by Dr. Stephen Henson of the OpenSSL development team.
Anon DH ServerKeyExchange with 0 p parameter (CVE-2015-1794)
============================================================
Severity: Low
If a client receives a ServerKeyExchange for an anonymous DH ciphersuite with
the value of p set to 0 then a seg fault can occur leading to a possible denial
of service attack.
This issue affects OpenSSL version 1.0.2.
OpenSSL 1.0.2 users should upgrade to 1.0.2e
This issue was reported to OpenSSL on August 3 2015 by Guy Leaver (Cisco). The
fix was developed by Matt Caswell of the OpenSSL development team.
Note
====
As per our previous announcements and our Release Strategy
(https://www.openssl.org/about/releasestrat.html), support for OpenSSL versions
1.0.0 and 0.9.8 will cease on 31st December 2015. No security updates for these
versions will be provided after that date. In the absence of significant
security issues being identified prior to that date, the 1.0.0t and 0.9.8zh
releases will be the last for those versions. Users of these versions are
advised to upgrade.
References
==========
URL for this Security Advisory:
https://www.openssl.org/news/secadv/20151203.txt
Note: the online version of the advisory may be updated with additional
details over time.
For details of OpenSSL severity classifications please see:
https://www.openssl.org/about/secpolicy.html
Changes since OpenSSH 6.9
=========================
This focus of this release is primarily to deprecate weak, legacy
and/or unsafe cryptography.
Security
--------
* sshd(8): OpenSSH 6.8 and 6.9 incorrectly set TTYs to be world-
writable. Local attackers may be able to write arbitrary messages
to logged-in users, including terminal escape sequences.
Reported by Nikolay Edigaryev.
* sshd(8): Portable OpenSSH only: Fixed a privilege separation
weakness related to PAM support. Attackers who could successfully
compromise the pre-authentication process for remote code
execution and who had valid credentials on the host could
impersonate other users. Reported by Moritz Jodeit.
* sshd(8): Portable OpenSSH only: Fixed a use-after-free bug
related to PAM support that was reachable by attackers who could
compromise the pre-authentication process for remote code
execution. Also reported by Moritz Jodeit.
* sshd(8): fix circumvention of MaxAuthTries using keyboard-
interactive authentication. By specifying a long, repeating
keyboard-interactive "devices" string, an attacker could request
the same authentication method be tried thousands of times in
a single pass. The LoginGraceTime timeout in sshd(8) and any
authentication failure delays implemented by the authentication
mechanism itself were still applied. Found by Kingcope.
Potentially-incompatible Changes
--------------------------------
* Support for the legacy SSH version 1 protocol is disabled by
default at compile time.
* Support for the 1024-bit diffie-hellman-group1-sha1 key exchange
is disabled by default at run-time. It may be re-enabled using
the instructions at http://www.openssh.com/legacy.html
* Support for ssh-dss, ssh-dss-cert-* host and user keys is disabled
by default at run-time. These may be re-enabled using the
instructions at http://www.openssh.com/legacy.html
* Support for the legacy v00 cert format has been removed.
* The default for the sshd_config(5) PermitRootLogin option has
changed from "yes" to "prohibit-password".
* PermitRootLogin=without-password/prohibit-password now bans all
interactive authentication methods, allowing only public-key,
hostbased and GSSAPI authentication (previously it permitted
keyboard-interactive and password-less authentication if those
were enabled).
New Features
------------
* ssh_config(5): add PubkeyAcceptedKeyTypes option to control which
public key types are available for user authentication.
* sshd_config(5): add HostKeyAlgorithms option to control which
public key types are offered for host authentications.
* ssh(1), sshd(8): extend Ciphers, MACs, KexAlgorithms,
HostKeyAlgorithms, PubkeyAcceptedKeyTypes and HostbasedKeyTypes
options to allow appending to the default set of algorithms
instead of replacing it. Options may now be prefixed with a '+'
to append to the default, e.g. "HostKeyAlgorithms=+ssh-dss".
* sshd_config(5): PermitRootLogin now accepts an argument of
'prohibit-password' as a less-ambiguous synonym of 'without-
password'.
Bugfixes
--------
* ssh(1), sshd(8): add compatability workarounds for Cisco and more
PuTTY versions. bz#2424
* Fix some omissions and errors in the PROTOCOL and PROTOCOL.mux
documentation relating to Unix domain socket forwarding;
bz#2421 bz#2422
* ssh(1): Improve the ssh(1) manual page to include a better
description of Unix domain socket forwarding; bz#2423
* ssh(1), ssh-agent(1): skip uninitialised PKCS#11 slots, fixing
failures to load keys when they are present. bz#2427
* ssh(1), ssh-agent(1): do not ignore PKCS#11 hosted keys that wth
empty CKA_ID; bz#2429
* sshd(8): clarify documentation for UseDNS option; bz#2045
the support in the rest of the source tree.
X11 sets could use some cleaning up perhaps (just deletion, as
we've never really marked the old X11R6 as obsolete for native
xorg using platforms so far either.)
*) Alternate chains certificate forgery
During certificate verfification, OpenSSL will attempt to find an
alternative certificate chain if the first attempt to build such a chain
fails. An error in the implementation of this logic can mean that an
attacker could cause certain checks on untrusted certificates to be
bypassed, such as the CA flag, enabling them to use a valid leaf
certificate to act as a CA and "issue" an invalid certificate.
This issue was reported to OpenSSL by Adam Langley/David Benjamin
(Google/BoringSSL).
[Matt Caswell]
=========================
This is primarily a bugfix release.
Security
--------
* ssh(1): when forwarding X11 connections with ForwardX11Trusted=no,
connections made after ForwardX11Timeout expired could be permitted
and no longer subject to XSECURITY restrictions because of an
ineffective timeout check in ssh(1) coupled with "fail open"
behaviour in the X11 server when clients attempted connections with
expired credentials. This problem was reported by Jann Horn.
* ssh-agent(1): fix weakness of agent locking (ssh-add -x) to
password guessing by implementing an increasing failure delay,
storing a salted hash of the password rather than the password
itself and using a timing-safe comparison function for verifying
unlock attempts. This problem was reported by Ryan Castellucci.
New Features
------------
* ssh(1), sshd(8): promote chacha20-poly1305@openssh.com to be the
default cipher
* sshd(8): support admin-specified arguments to AuthorizedKeysCommand;
bz#2081
* sshd(8): add AuthorizedPrincipalsCommand that allows retrieving
authorized principals information from a subprocess rather than
a file.
* ssh(1), ssh-add(1): support PKCS#11 devices with external PIN
entry devices bz#2240
* sshd(8): allow GSSAPI host credential check to be relaxed for
multihomed hosts via GSSAPIStrictAcceptorCheck option; bz#928
* ssh-keygen(1): support "ssh-keygen -lF hostname" to search
known_hosts and print key hashes rather than full keys.
* ssh-agent(1): add -D flag to leave ssh-agent in foreground without
enabling debug mode; bz#2381
Bugfixes
--------
* ssh(1), sshd(8): deprecate legacy SSH2_MSG_KEX_DH_GEX_REQUEST_OLD
message and do not try to use it against some 3rd-party SSH
implementations that use it (older PuTTY, WinSCP).
* Many fixes for problems caused by compile-time deactivation of
SSH1 support (including bz#2369)
* ssh(1), sshd(8): cap DH-GEX group size at 4Kbits for Cisco
implementations as some would fail when attempting to use group
sizes >4K; bz#2209
* ssh(1): fix out-of-bound read in EscapeChar configuration option
parsing; bz#2396
* sshd(8): fix application of PermitTunnel, LoginGraceTime,
AuthenticationMethods and StreamLocalBindMask options in Match
blocks
* ssh(1), sshd(8): improve disconnection message on TCP reset;
bz#2257
* ssh(1): remove failed remote forwards established by muliplexing
from the list of active forwards; bz#2363
* sshd(8): make parsing of authorized_keys "environment=" options
independent of PermitUserEnv being enabled; bz#2329
* sshd(8): fix post-auth crash with permitopen=none; bz#2355
* ssh(1), ssh-add(1), ssh-keygen(1): allow new-format private keys
to be encrypted with AEAD ciphers; bz#2366
* ssh(1): allow ListenAddress, Port and AddressFamily configuration
options to appear in any order; bz#86
* sshd(8): check for and reject missing arguments for VersionAddendum
and ForceCommand; bz#2281
* ssh(1), sshd(8): don't treat unknown certificate extensions as
fatal; bz#2387
* ssh-keygen(1): make stdout and stderr output consistent; bz#2325
* ssh(1): mention missing DISPLAY environment in debug log when X11
forwarding requested; bz#1682
* sshd(8): correctly record login when UseLogin is set; bz#378
* sshd(8): Add some missing options to sshd -T output and fix output
of VersionAddendum and HostCertificate. bz#2346
* Document and improve consistency of options that accept a "none"
argument" TrustedUserCAKeys, RevokedKeys (bz#2382),
AuthorizedPrincipalsFile (bz#2288)
* ssh(1): include remote username in debug output; bz#2368
* sshd(8): avoid compatibility problem with some versions of Tera
Term, which would crash when they received the hostkeys notification
message (hostkeys-00@openssh.com)
* sshd(8): mention ssh-keygen -E as useful when comparing legacy MD5
host key fingerprints; bz#2332
* ssh(1): clarify pseudo-terminal request behaviour and use make
manual language consistent; bz#1716
* ssh(1): document that the TERM environment variable is not subject
to SendEnv and AcceptEnv; bz#2386
*) Malformed ECParameters causes infinite loop
When processing an ECParameters structure OpenSSL enters an infinite loop
if the curve specified is over a specially malformed binary polynomial
field.
This can be used to perform denial of service against any
system which processes public keys, certificate requests or
certificates. This includes TLS clients and TLS servers with
client authentication enabled.
This issue was reported to OpenSSL by Joseph Barr-Pixton.
(CVE-2015-1788)
[Andy Polyakov]
*) Exploitable out-of-bounds read in X509_cmp_time
X509_cmp_time does not properly check the length of the ASN1_TIME
string and can read a few bytes out of bounds. In addition,
X509_cmp_time accepts an arbitrary number of fractional seconds in the
time string.
An attacker can use this to craft malformed certificates and CRLs of
various sizes and potentially cause a segmentation fault, resulting in
a DoS on applications that verify certificates or CRLs. TLS clients
that verify CRLs are affected. TLS clients and servers with client
authentication enabled may be affected if they use custom verification
callbacks.
This issue was reported to OpenSSL by Robert Swiecki (Google), and
independently by Hanno Böck.
(CVE-2015-1789)
[Emilia Käsper]
*) PKCS7 crash with missing EnvelopedContent
The PKCS#7 parsing code does not handle missing inner EncryptedContent
correctly. An attacker can craft malformed ASN.1-encoded PKCS#7 blobs
with missing content and trigger a NULL pointer dereference on parsing.
Applications that decrypt PKCS#7 data or otherwise parse PKCS#7
structures from untrusted sources are affected. OpenSSL clients and
servers are not affected.
This issue was reported to OpenSSL by Michal Zalewski (Google).
(CVE-2015-1790)
[Emilia Käsper]
*) CMS verify infinite loop with unknown hash function
When verifying a signedData message the CMS code can enter an infinite loop
if presented with an unknown hash function OID. This can be used to perform
denial of service against any system which verifies signedData messages using
the CMS code.
This issue was reported to OpenSSL by Johannes Bauer.
(CVE-2015-1792)
[Stephen Henson]
*) Race condition handling NewSessionTicket
If a NewSessionTicket is received by a multi-threaded client when attempting to
reuse a previous ticket then a race condition can occur potentially leading to
a double free of the ticket data.
(CVE-2015-1791)
[Matt Caswell]
*) Reject DH handshakes with parameters shorter than 768 bits.
[Kurt Roeckx and Emilia Kasper]
