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List:       secunia-sec-adv
Subject:    [SA11534] Apache mod_ssl "ssl_util_uuencode_binary()" Buffer Overflow Vulnerability
From:       Secunia Security Advisories <sec-adv () secunia ! com>
Date:       2004-05-28 9:08:39
Message-ID: 200405280908.i4S98dlV000357 () secunia ! com
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TITLE:
Apache mod_ssl "ssl_util_uuencode_binary()" Buffer Overflow
Vulnerability

SECUNIA ADVISORY ID:
SA11534

VERIFY ADVISORY:
http://secunia.com/advisories/11534/

CRITICAL:
Moderately critical

IMPACT:
DoS, System access

WHERE:
From remote

SOFTWARE:
mod_ssl 2.x
Apache 1.3.x
Apache  2.0.x

DESCRIPTION:
Georgi Guninski has discovered a vulnerability in mod_ssl, which
potentially can be exploited by malicious people to cause a DoS
(Denial of Service) or compromise a vulnerable system.

The vulnerability is caused due to a boundary error within the
"ssl_util_uuencode_binary()" function when handling client
certificates. This can potentially be exploited to cause a
stack-based buffer overflow by sending a specially crafted client
certificate containing an overly long subject DN (more than 6KB).

Successful exploitation requires that the "FakeBasicAuth" option is
enabled and that the malicious client certificate is issued from a
trusted CA (Certificate Authority).

SOLUTION:
Update to version 2.8.18 for Apache 1.3.31:
http://www.modssl.org/source/mod_ssl-2.8.18-1.3.31.tar.gz

A fix for the Apache 2.0 branch is available via CVS:
http://cvs.apache.org/viewcvs.cgi/httpd-2.0/modules/ssl/ssl_engine_kernel.c?r1=1.105&r2=1.106

PROVIDED AND/OR DISCOVERED BY:
Georgi Guninski

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