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OpenVPN Format String and Denial of Service Vulnerabilities
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Secunia Advisory:
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SA17376
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Release Date:
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2005-11-01
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Last Update:
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2005-11-07
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Popularity:
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9,382 views
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Critical:
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Moderately critical
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Impact:
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DoS
System access
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Where:
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From remote
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Solution Status:
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Vendor Patch
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| Software: | OpenVPN 2.x
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| CVE reference: | CVE-2005-3393
CVE-2005-3409
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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
Changelog:
2005-11-07: Added CVE references.
Original Advisory:
OpenVPN:
http://openvpn.net/changelog.html
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Please note: The information that this Secunia Advisory is based on comes from a third party unless stated otherwise.
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