TITLE:
OpenSSL Potential SSL 2.0 Rollback Vulnerability

SECUNIA ADVISORY ID:
SA17151

VERIFY ADVISORY:
http://secunia.com/advisories/17151/

CRITICAL:
Less critical

IMPACT:
Security Bypass

WHERE:
>From remote

SOFTWARE:
OpenSSL 0.9.x
http://secunia.com/product/253/

DESCRIPTION:
A vulnerability has been reported in OpenSSL, which potentially can
be exploited by malicious people to bypass certain security
restrictions.

The vulnerability is caused due to an error in handling the use of
SSL_OP_MSIE_SSLV2_RSA_PADDING option. The use of this option causes a
verification check that prevents protocol-version rollback attacks to
be disabled. This may be exploited in "man-in-the-middle" attacks to
force a client and a server to negotiate the less secure SSL 2.0
protocol even when both parties support the more secure SSL 3.0 or
TLS 1.0 protocols. The option is also enabled when the SSL_OP_ALL
option is used.

Successful exploitation requires that SSL 2.0 is enabled, and either
the SSL_OP_MSIE_SSLV2_RSA_PADDING or the SSL_OP_ALL option is used.

The vulnerability has been reported in all versions prior to 0.9.7h,
and prior to 0.9.8a.

Applications that use the OpenSSL SSL/TLS server implementation are
potentially affected.

SOLUTION:
Update to the fixed versions or apply patch.
http://www.openssl.org/source/

OpenSSL 0.9.7 branch:
Update to version 0.9.7h or later.

OpenSSL 0.9.8 branch:
Update to version 0.9.8a or later.

The vendor provides the following source code patch for the 0.9.6,
0.9.7, and 0.9.8 OpenSSL branches for users who are unable to perform
a version update.
http://www.openssl.org/news/patch-CAN-2005-2969.txt

PROVIDED AND/OR DISCOVERED BY:
The vendor credits Yutaka Oiwa, Research Center for Information
Security, National Institute of Advanced Industrial Science and
Technology (AIST), Japan.

ORIGINAL ADVISORY:
http://www.openssl.org/news/secadv_20051011.txt

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