The DTLS implementation provides some protection against replay attacks
in accordance with RFC6347 section 4.1.2.6.
A sliding "window" of valid record sequence numbers is maintained with
the "right" hand edge of the window set to the highest sequence number we
have received so far. Records that arrive that are off the "left" hand
edge of the window are rejected. Records within the window are checked
against a list of records received so far. If we already received it then
we also reject the new record.
If we have not already received the record, or the sequence number is off
the right hand edge of the window then we verify the MAC of the record.
If MAC verification fails then we discard the record. Otherwise we mark
the record as received. If the sequence number was off the right hand edge
of the window, then we slide the window along so that the right hand edge
is in line with the newly received sequence number.
Records may arrive for future epochs, i.e. a record from after a CCS being
sent, can arrive before the CCS does if the packets get re-ordered. As we
have not yet received the CCS we are not yet in a position to decrypt or
validate the MAC of those records. OpenSSL places those records on an
unprocessed records queue. It additionally updates the window immediately,
even though we have not yet verified the MAC. This will only occur if
currently in a handshake/renegotiation.
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 the right hand edge of the window is
moved very far to the right, and all subsequent legitimate packets are
dropped causing a denial of service.
A similar effect can be achieved during the initial handshake. In this
case there is no MAC key negotiated yet. Therefore an attacker can send a
message for the current epoch with a very large sequence number. The code
will process the record as normal. If the hanshake message sequence number
(as opposed to the record sequence number that we have been talking about
so far) is in the future then the injected message is bufferred to be
handled later, but the window is still updated. Therefore all subsequent
legitimate handshake records are dropped. This aspect is not considered a
security issue because there are many ways for an attacker to disrupt the
initial handshake and prevent it from completing successfully (e.g.
injection of a handshake message will cause the Finished MAC to fail and
the handshake to be aborted). This issue comes about as a result of trying
to do replay protection, but having no integrity mechanism in place yet.
Does it even make sense to have replay protection in epoch 0? That
issue isn't addressed here though.
This addressed an OCAP Audit issue.
CVE-2016-2181
Reviewed-by: Richard Levitte <levitte@openssl.org>
Modified version of the commit ffaef3f15 in the master branch by Stephen
Henson. This makes the SSL_OP_SINGLE_DH_USE option a no-op and always
generates a new DH key for every handshake regardless.
This is a follow on from CVE-2016-0701. This branch is not impacted by
that CVE because it does not support X9.42 style parameters. It is still
possible to generate parameters based on primes that are not "safe",
although by default OpenSSL does not do this. The documentation does
sign post that using such parameters is unsafe if the private DH key is
reused. However to avoid accidental problems or future attacks this commit
has been backported to this branch.
Issue reported by Antonio Sanso
Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
There are lots of calls to EVP functions from within libssl There were
various places where we should probably check the return value but don't.
This adds these checks.
Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit 56d913467541506572f908a34c32ca7071f77a94)
Conflicts:
ssl/s3_enc.c
ssl/s3_srvr.c
If a client receives a ServerKeyExchange for an anon DH ciphersuite with the
value of p set to 0 then a seg fault can occur. This commits adds a test to
reject p, g and pub key parameters that have a 0 value (in accordance with
RFC 5246)
The security vulnerability only affects master and 1.0.2, but the fix is
additionally applied to 1.0.1 for additional confidence.
CVE-2015-1794
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
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
This also fixes RT#3808 where a session ID is changed for a session already
in the client session cache. Since the session ID is the key to the cache
this breaks the cache access.
Parts of this patch were inspired by this Akamai change:
c0bf69a791
Reviewed-by: Rich Salz <rsalz@openssl.org>
(cherry picked from commit 27c76b9b8010b536687318739c6f631ce4194688)
Conflicts:
ssl/ssl.h
ssl/ssl_err.c
Since the client has no way of communicating her supported parameter
range to the server, connections to servers that choose weak DH will
simply fail.
Reviewed-by: Kurt Roeckx <kurt@openssl.org>
Reusing an SSL object when it has encountered a fatal error can
have bad consequences. This is a bug in application code not libssl
but libssl should be more forgiving and not crash.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(cherry picked from commit a89db885e0d8aac3a9df1bbccb0c1ddfd8b2e10a)
Conflicts:
ssl/s3_srvr.c
ssl/ssl_stat.c
EAP-FAST session resumption relies on handshake message lookahead
to determine server intentions. Commits
980bc1ec6114f5511b20c2e6ca741e61a39b99d6
and
7b3ba508af5c86afe43e28174aa3c53a0a24f4d9
removed the lookahead so broke session resumption.
This change partially reverts the commits and brings the lookahead back
in reduced capacity for TLS + EAP-FAST only. Since EAP-FAST does not
support regular session tickets, the lookahead now only checks for a
Finished message.
Regular handshakes are unaffected by this change.
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(cherry picked from commit 6e3d015363ed09c4eff5c02ad41153387ffdf5af)
They are moved to the COMPLEMENTOFDEFAULT instead.
This also fixes SSLv2 to be part of COMPLEMENTOFDEFAULT.
Reviewed-by: Rich Salz <rsalz@openssl.org>
(cherry picked from commit f417997a324037025be61737288e40e171a8218c)
Conflicts:
ssl/ssl_ciph.c
Sometimes it fails to format them very well, and sometimes it corrupts them!
This commit moves some particularly problematic ones.
Conflicts:
crypto/bn/bn.h
crypto/ec/ec_lcl.h
crypto/rsa/rsa.h
demos/engines/ibmca/hw_ibmca.c
ssl/ssl.h
ssl/ssl3.h
Conflicts:
crypto/ec/ec_lcl.h
ssl/tls1.h
Reviewed-by: Tim Hudson <tjh@openssl.org>
indent will not alter them when reformatting comments
(cherry picked from commit 1d97c8435171a7af575f73c526d79e1ef0ee5960)
Conflicts:
crypto/bn/bn_lcl.h
crypto/bn/bn_prime.c
crypto/engine/eng_all.c
crypto/rc4/rc4_utl.c
crypto/sha/sha.h
ssl/kssl.c
ssl/t1_lib.c
Conflicts:
crypto/rc4/rc4_enc.c
crypto/x509v3/v3_scts.c
crypto/x509v3/v3nametest.c
ssl/d1_both.c
ssl/s3_srvr.c
ssl/ssl.h
ssl/ssl_locl.h
ssl/ssltest.c
ssl/t1_lib.c
Reviewed-by: Tim Hudson <tjh@openssl.org>
OpenSSL clients would tolerate temporary RSA keys in non-export
ciphersuites. It also had an option SSL_OP_EPHEMERAL_RSA which
enabled this server side. Remove both options as they are a
protocol violation.
Thanks to Karthikeyan Bhargavan for reporting this issue.
(CVE-2015-0204)
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 4b4c1fcc88aec8c9e001b0a0077d3cd4de1ed0e6)
Conflicts:
doc/ssl/SSL_CTX_set_options.pod
and instead use the value provided by the underlying BIO. Also provide some
new DTLS_CTRLs so that the library user can set the mtu without needing to
know this constant. These new DTLS_CTRLs provide the capability to set the
link level mtu to be used (i.e. including this IP/UDP overhead). The previous
DTLS_CTRLs required the library user to subtract this overhead first.
Reviewed-by: Tim Hudson <tjh@openssl.org>
(cherry picked from commit 59669b6abf620d1ed2ef4d1e2df25c998b89b64d)
Conflicts:
ssl/d1_both.c
ssl/ssl_lib.c
When no-ssl3 is set only make SSLv3 disabled by default. Retain -ssl3
options for s_client/s_server/ssltest.
When no-ssl3-method is set SSLv3_*method() is removed and all -ssl3
options.
We should document this somewhere, e.g. wiki, FAQ or manual page.
Reviewed-by: Emilia Käsper <emilia@openssl.org>
(cherry picked from commit 3881d8106df732fc433d30446625dfa2396da42d)
Conflicts:
util/mkdef.pl
Don't call internal functions directly call them through
SSL_test_functions(). This also makes unit testing work on
Windows and platforms that don't export internal functions
from shared libraries.
By default unit testing is not enabled: it requires the compile
time option "enable-unit-test".
Reviewed-by: Geoff Thorpe <geoff@openssl.org>
(cherry picked from commit e0fc7961c4fbd27577fb519d9aea2dc788742715)
Conflicts:
ssl/Makefile
util/mkdef.pl
SRP ciphersuites do not have no authentication. They have authentication
based on SRP. Add new SRP authentication flag and cipher string.
(cherry picked from commit a86b88acc373ac1fb0ca709a5fb8a8fa74683f67)
Add TLS padding extension to SSL_OP_ALL so it is used with other
"bugs" options and can be turned off.
This replaces SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG which is an ancient
option referring to SSLv2 and SSLREF.
PR#3336
The flag SSL_OP_MSIE_SSLV2_RSA_PADDING hasn't done anything since OpenSSL
0.9.7h but deleting it will break source compatibility with any software
that references it. Restore it but #define to zero.
(cherry picked from commit b17d6b8d1d49fa4732deff17cfd1833616af0d9c)
(I'd rather use an option, but it appears that the options field is
full.)
Now, we send the time in the gmt_unix_time field if the appropriate
one of these mode options is set, but randomize the field if the flag
is not set.
New function to retrieve compression method from SSL_SESSION structure.
Delete SSL_SESSION_get_id_len and SSL_SESSION_get0_id functions
as they duplicate functionality of SSL_SESSION_get_id. Note: these functions
have never appeared in any release version of OpenSSL.
Submitted by: Peter Sylvester <peter.sylvester@edelweb.fr>
Reviewed by: steve
Remove unnecessary code for srp and to add some comments to
s_client.
- the callback to provide a user during client connect is
no longer necessary since rfc 5054 a connection attempt
with an srp cipher and no user is terminated when the
cipher is acceptable
- comments to indicate in s_client the (non-)usefulness of
th primalaty tests for non known group parameters.
