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ESB-2009.0020 -- [FreeBSD] -- OpenSSL incorrectly checks for malformed signatures

Date: 08 January 2009
References: ESB-2009.0009  ESB-2009.0195  AA-2009.0079  AL-2009.0042  

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===========================================================================
             AUSCERT External Security Bulletin Redistribution

                        ESB-2009.0020 -- [FreeBSD]
            OpenSSL incorrectly checks for malformed signatures
                              8 January 2009

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:              openssl
Publisher:            FreeBSD
Operating System:     FreeBSD
Impact:               Provide Misleading Information
Access:               Remote/Unauthenticated
CVE Names:            CVE-2008-5077

Ref:                  ESB-2009.0009

Original Bulletin:    
  ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-09:02.openssl.asc

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=============================================================================
FreeBSD-SA-09:02.openssl                                    Security Advisory
                                                          The FreeBSD Project

Topic:          OpenSSL incorrectly checks for malformed signatures

Category:       contrib
Module:         openssl
Announced:      2009-01-07
Credits:        Google Security Team
Affects:        All FreeBSD releases
Corrected:      2009-01-07 21:03:41 UTC (RELENG_7, 7.1-STABLE)
                2009-01-07 20:17:55 UTC (RELENG_7_1, 7.1-RELEASE-p1)
                2009-01-07 20:17:55 UTC (RELENG_7_0, 7.0-RELEASE-p8)
                2009-01-07 20:17:55 UTC (RELENG_6, 6.4-STABLE)
                2009-01-07 20:17:55 UTC (RELENG_6_4, 6.4-RELEASE-p2)
                2009-01-07 20:17:55 UTC (RELENG_6_3, 6.3-RELEASE-p8)
CVE Name:       CVE-2008-5077

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit <URL:http://security.FreeBSD.org/>.

I.   Background

FreeBSD includes software from the OpenSSL Project.  The OpenSSL Project is
a collaborative effort to develop a robust, commercial-grade, full-featured
Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3)
and Transport Layer Security (TLS v1) protocols as well as a full-strength
general purpose cryptography library.

II.  Problem Description

The EVP_VerifyFinal() function from OpenSSL is used to determine if a
digital signature is valid.  The SSL layer in OpenSSL uses
EVP_VerifyFinal(), which in several places checks the return value
incorrectly and treats verification errors as a good signature.  This
is only a problem for DSA and ECDSA keys.

III. Impact

For applications using OpenSSL for SSL connections, an invalid SSL
certificate may be interpreted as valid.  This could for example be
used by an attacker to perform a man-in-the-middle attack.

Other applications which use the OpenSSL EVP API may similarly be
affected.

IV.  Workaround

For a server an RSA signed certificate may be used instead of DSA or
ECDSA based certificate.

Note that Mozilla Firefox does not use OpenSSL and thus is not
affected.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 6-STABLE, or 7-STABLE, or to the
RELENG_7_1, RELENG_7_0, RELENG_6_4, or RELENG_6_3 security branch
dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 6.3, 6.4,
7.0, and 7.1 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 7.x]
# fetch http://security.FreeBSD.org/patches/SA-09:02/openssl.patch
# fetch http://security.FreeBSD.org/patches/SA-09:02/openssl.patch.asc

[FreeBSD 6.x]
# fetch http://security.FreeBSD.org/patches/SA-09:02/openssl6.patch
# fetch http://security.FreeBSD.org/patches/SA-09:02/openssl6.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/secure/lib/libssl
# make obj && make depend && make && make install
# cd /usr/src/secure/usr.bin/openssl
# make obj && make depend && make && make install

NOTE: On the amd64 platform, the above procedure will not update the
lib32 (i386 compatibility) libraries.  On amd64 systems where the i386
compatibility libraries are used, the operating system should instead
be recompiled as described in
<URL:http://www.FreeBSD.org/handbook/makeworld.html>

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

CVS:

Branch                                                           Revision
  Path
- - -------------------------------------------------------------------------
RELENG_6
  src/crypto/openssl/apps/speed.c                                1.13.2.1
  src/crypto/openssl/apps/verify.c                           1.1.1.5.12.1
  src/crypto/openssl/apps/x509.c                             1.1.1.10.2.1
  src/crypto/openssl/apps/spkac.c                            1.1.1.4.12.1
  src/crypto/openssl/ssl/s2_srvr.c                               1.12.2.1
  src/crypto/openssl/ssl/s3_clnt.c                           1.1.1.12.2.1
  src/crypto/openssl/ssl/s3_srvr.c                           1.1.1.14.2.2
  src/crypto/openssl/ssl/s2_clnt.c                               1.13.2.2
RELENG_6_4
  src/UPDATING                                             1.416.2.40.2.5
  src/sys/conf/newvers.sh                                   1.69.2.18.2.8
  src/crypto/openssl/apps/speed.c                               1.13.12.1
  src/crypto/openssl/apps/verify.c                           1.1.1.5.24.1
  src/crypto/openssl/apps/x509.c                            1.1.1.10.12.1
  src/crypto/openssl/apps/spkac.c                            1.1.1.4.24.1
  src/crypto/openssl/ssl/s2_srvr.c                              1.12.12.1
  src/crypto/openssl/ssl/s3_clnt.c                          1.1.1.12.12.1
  src/crypto/openssl/ssl/s3_srvr.c                       1.1.1.14.2.1.6.1
  src/crypto/openssl/ssl/s2_clnt.c                           1.13.2.1.6.1
RELENG_6_3
  src/UPDATING                                            1.416.2.37.2.13
  src/sys/conf/newvers.sh                                  1.69.2.15.2.12
  src/crypto/openssl/apps/speed.c                               1.13.10.1
  src/crypto/openssl/apps/verify.c                           1.1.1.5.22.1
  src/crypto/openssl/apps/x509.c                            1.1.1.10.10.1
  src/crypto/openssl/apps/spkac.c                            1.1.1.4.22.1
  src/crypto/openssl/ssl/s2_srvr.c                              1.12.10.1
  src/crypto/openssl/ssl/s3_clnt.c                          1.1.1.12.10.1
  src/crypto/openssl/ssl/s3_srvr.c                       1.1.1.14.2.1.4.1
  src/crypto/openssl/ssl/s2_clnt.c                           1.13.2.1.4.1
RELENG_7
  src/crypto/openssl/apps/speed.c                                1.15.2.1
  src/crypto/openssl/apps/verify.c                            1.1.1.6.2.1
  src/crypto/openssl/apps/x509.c                             1.1.1.11.2.1
  src/crypto/openssl/apps/spkac.c                             1.1.1.5.2.1
  src/crypto/openssl/ssl/s2_srvr.c                               1.13.2.1
  src/crypto/openssl/ssl/s3_clnt.c                           1.1.1.14.2.1
  src/crypto/openssl/ssl/s3_srvr.c                           1.1.1.17.2.1
  src/crypto/openssl/ssl/ssltest.c                           1.1.1.10.2.1
  src/crypto/openssl/ssl/s2_clnt.c                               1.15.2.1
RELENG_7_1
  src/UPDATING                                             1.507.2.13.2.4
  src/sys/conf/newvers.sh                                    1.72.2.9.2.5
  src/crypto/openssl/apps/speed.c                                1.15.6.1
  src/crypto/openssl/apps/verify.c                            1.1.1.6.6.1
  src/crypto/openssl/apps/x509.c                             1.1.1.11.6.1
  src/crypto/openssl/apps/spkac.c                             1.1.1.5.6.1
  src/crypto/openssl/ssl/s2_srvr.c                               1.13.6.1
  src/crypto/openssl/ssl/s3_clnt.c                           1.1.1.14.6.1
  src/crypto/openssl/ssl/s3_srvr.c                           1.1.1.17.6.1
  src/crypto/openssl/ssl/ssltest.c                           1.1.1.10.6.1
  src/crypto/openssl/ssl/s2_clnt.c                               1.15.6.1
RELENG_7_0
  src/UPDATING                                             1.507.2.3.2.12
  src/sys/conf/newvers.sh                                   1.72.2.5.2.12
  src/crypto/openssl/apps/speed.c                                1.15.4.1
  src/crypto/openssl/apps/verify.c                            1.1.1.6.4.1
  src/crypto/openssl/apps/x509.c                             1.1.1.11.4.1
  src/crypto/openssl/apps/spkac.c                             1.1.1.5.4.1
  src/crypto/openssl/ssl/s2_srvr.c                               1.13.4.1
  src/crypto/openssl/ssl/s3_clnt.c                           1.1.1.14.4.1
  src/crypto/openssl/ssl/s3_srvr.c                           1.1.1.17.4.1
  src/crypto/openssl/ssl/ssltest.c                           1.1.1.10.4.1
  src/crypto/openssl/ssl/s2_clnt.c                               1.15.4.1
- - -------------------------------------------------------------------------

Subversion:

Branch/path                                                      Revision
- - -------------------------------------------------------------------------
stable/6/                                                         r186873
releng/6.4/                                                       r186872
releng/6.3/                                                       r186872
stable/7/                                                         r186872
releng/7.1/                                                       r186872
releng/7.0/                                                       r186872
- - -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-5077
http://www.openssl.org/news/secadv_20090107.txt

The latest revision of this advisory is available at
http://security.FreeBSD.org/advisories/FreeBSD-SA-09:02.openssl.asc
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===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
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Qld 4072

Internet Email: auscert@auscert.org.au
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