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OpenVPN Format String and Denial of Service Vulnerabilities
Secunia Advisory: SA17376
Release Date: 2005-11-01
Last Update: 2005-11-07
Popularity: 11,260 views

Critical:
Moderately critical
Impact: DoS
System access
Where: From remote
Solution Status: Vendor Patch

Software:OpenVPN 2.x

Secunia CVSS-2 Score: Available in Secunia business solutions

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Advisory Content (Page 1 of 3)[ 1 ] [ 2 ] [ 3 ]

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.

Change Page:
[ 1 ] [ 2 ] [ 3 ]



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