CVE-2012-4677 in Tunnelblick
Summary
by MITRE
Tunnelblick 3.3beta20 and earlier allows local users to gain privileges by using a crafted Info.plist file to control the gOkIfNotSecure value.
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Analysis
by VulDB Data Team • 02/20/2019
The vulnerability identified as CVE-2012-4677 affects Tunnelblick versions 3.3beta20 and earlier, representing a significant privilege escalation flaw within the OpenVPN client implementation for macOS. This issue stems from inadequate input validation and security controls within the application's handling of configuration files, specifically the Info.plist file that governs application behavior and security parameters. The vulnerability exists in the way Tunnelblick processes the gOkIfNotSecure value, which is a critical security parameter that determines whether the application should proceed with network configuration despite potential security concerns.
The technical exploitation of this vulnerability occurs through manipulation of the Info.plist configuration file, where a local attacker can craft a malicious payload that alters the gOkIfNotSecure parameter to bypass security checks. This flaw operates at the application-level privilege boundary, allowing a local user to escalate their privileges from standard user level to elevated permissions that would normally be restricted. The vulnerability is classified as a privilege escalation issue under CWE-269, which specifically addresses improper privilege management in software applications. The flaw demonstrates a clear failure in access control mechanisms, where the application fails to properly validate or sanitize input from user-controlled configuration files before applying security-relevant parameters.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with potential access to sensitive network configurations and potentially sensitive data that the application might handle. Attackers can leverage this vulnerability to execute arbitrary code with elevated privileges, potentially compromising the entire system or gaining access to protected network resources. The vulnerability is particularly concerning in environments where Tunnelblick is used for enterprise network access, as it could enable attackers to bypass security controls and gain unauthorized access to corporate networks. This flaw aligns with ATT&CK technique T1068 which covers local privilege escalation, and specifically addresses the use of application configuration files as attack vectors.
Mitigation strategies for CVE-2012-4677 require immediate patching of affected Tunnelblick versions to the latest stable release that contains the security fix. Organizations should also implement strict access controls and monitoring for configuration file modifications, particularly for applications that handle network security parameters. The fix typically involves enhanced validation of the Info.plist file contents and stricter enforcement of security parameters such as gOkIfNotSecure. System administrators should conduct thorough security audits of all OpenVPN client installations and ensure that automatic updates are enabled to prevent exploitation of known vulnerabilities. Additional protective measures include implementing application whitelisting policies and monitoring for unauthorized changes to critical system configuration files, which would help detect potential exploitation attempts before they can be successfully executed.