CVE-2012-3486 in Tunnelblick
Summary
by MITRE
Tunnelblick 3.3beta20 and earlier allows local users to gain privileges via an OpenVPN configuration file that specifies execution of a script upon occurrence of an OpenVPN event.
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Analysis
by VulDB Data Team • 02/20/2019
The vulnerability identified as CVE-2012-3486 affects Tunnelblick versions 3.3beta20 and earlier, representing a critical privilege escalation flaw that exploits the software's handling of OpenVPN configuration files. This issue stems from insufficient input validation and privilege management within the Tunnelblick application, which processes OpenVPN configuration files that may contain script execution directives. The vulnerability specifically targets the manner in which Tunnelblick interprets and executes scripts associated with OpenVPN events, creating an attack vector where local users can manipulate the system's privilege level through carefully crafted configuration files.
The technical implementation of this vulnerability involves the improper handling of script execution permissions within the OpenVPN event processing framework. When Tunnelblick encounters an OpenVPN configuration file containing script directives, it fails to properly validate or restrict the execution context of these scripts, allowing local attackers to specify arbitrary commands that execute with elevated privileges. This flaw operates under CWE-78, which addresses improper neutralization of special elements used in OS commands, and specifically manifests as a privilege escalation vulnerability where unprivileged users can leverage the application's trust in configuration files to execute malicious code with higher privileges than intended. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1068, which involves the exploitation of local privilege escalation mechanisms.
The operational impact of CVE-2012-3486 extends beyond simple unauthorized access, as it provides attackers with the capability to execute arbitrary commands with elevated system privileges. This creates a significant risk for environments where Tunnelblick is used to manage VPN connections, particularly in scenarios where users may have access to configuration files or where the application runs with elevated permissions. Attackers can exploit this vulnerability to install backdoors, modify system configurations, access sensitive data, or establish persistent access to the compromised system. The vulnerability is particularly concerning because it operates at the local user level, meaning that any user with access to modify OpenVPN configuration files can potentially exploit this flaw, making it a widespread concern for organizations that rely on Tunnelblick for network connectivity management.
Mitigation strategies for CVE-2012-3486 should prioritize immediate software updates to versions that address the privilege escalation vulnerability, as the original affected versions are no longer supported and lack security patches. Organizations should implement strict access controls over OpenVPN configuration files, ensuring that only authorized administrators can modify these critical components. Additionally, system administrators should consider implementing script execution restrictions and monitoring mechanisms that can detect unauthorized script execution attempts. The remediation approach should include comprehensive security assessments of all VPN client configurations, particularly focusing on script execution permissions and the trust model applied to configuration file processing. Network segmentation and privilege separation measures can further reduce the attack surface by limiting the potential impact of successful exploitation attempts.