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Vulnerability of OpenVPN: no authentication for management interface

Synthesis of the vulnerability 

When administration interface is activated, an attacker can connect without authenticating, because access password is optional.
Vulnerable software: Unix (platform) ~ not comprehensive.
Severity of this announce: 1/4.
Creation date: 04/05/2006.
Références of this computer vulnerability: CVE-2006-2229, VIGILANCE-VUL-5815.

Description of the vulnerability 

Administrator can activate administration interface which uses a text protocol, without encryption, listening on a TCP port. This service generally listens on 127.0.0.1 to only allow local users to access it.

The administrative interface is activated using following parameter of OpenVPN:
  --management IP port [password-file]

However, file containing passwords is facultative. An administrator then could forget to add it. In this case, all local users can administer OpenVPN by connecting to this port using telnet.
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This security note impacts software or systems such as Unix (platform) ~ not comprehensive.

Our Vigil@nce team determined that the severity of this threat announce is low.

The trust level is of type confirmed by a trusted third party, with an origin of intranet client.

An attacker with a expert ability can exploit this computer weakness announce.

Solutions for this threat 

OpenVPN: workaround for missing authentication.
A workaround is to ensure that a password is activated. For example:
 --management 127.0.0.1 IP 7505 file_containing_a_password
More information:
  http://openvpn.net/management.html
  man 8 openvpn
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