Georgi Guninski has discovered a vulnerability in mod_ssl versions below 2.8.17, which potentially can be exploited by malicious people to cause a DoS (Denial of Service) or compromise a vulnerable system. Successful exploitation requires that the FakeBasicAuth option is enabled and that the malicious client certificate is issued from a trusted CA (Certificate Authority).
9510c3cbe496d79d6ba299e4a9cfefccde6cd32836986fc9c388bc98a38277d8
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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