FreeBSD Security Advisory - 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.
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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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