TITLE:
OpenVPN Format String and Denial of Service Vulnerabilities

SECUNIA ADVISORY ID:
SA17376

VERIFY ADVISORY:
http://secunia.com/advisories/17376/

CRITICAL:
Moderately critical

IMPACT:
DoS, System access

WHERE:
>From remote

SOFTWARE:
OpenVPN 2.x
http://secunia.com/product/5568/

DESCRIPTION:
Two vulnerabilities have been reported in OpenVPN, which can be
exploited by malicious people to cause a DoS (Denial of Service) and
potentially to compromise a user's system.

1) A format string error exists in the "foreign_option()" function in
"options.c" when handling command options pushed from the server (e.g.
"dhcp-option"). This can potentially be exploited by a malicious or
compromised server to execute arbitrary code on the OpenVPN client. 

Successful exploitation requires that e.g. the user is tricked into
connecting to a malicious VPN server, and the "pull" option is
enabled in the client's configuration file. However, it has reported
that enabling the "pull" option may not be required.

The vulnerability has been reported in all OpenVPN 2.0 versions, and
affects only non-Windows OpenVPN clients.

2) A NULL pointer dereferencing error in the OpenVPN server when
running in TCP mode may be exploited to crash the service. This is
caused due to the exception handler dereferencing a NULL pointer when
the "accept()" call fails.

The vulnerability has been reported in all OpenVPN 2.0 versions.

SOLUTION:
Update to version 2.0.3.
http://openvpn.net/download.html

PROVIDED AND/OR DISCOVERED BY:
1) vade79

ORIGINAL ADVISORY:
OpenVPN:
http://openvpn.net/changelog.html

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