CVE-2012-3485 in Tunnelblick
Summary
by MITRE
Tunnelblick 3.3beta20 and earlier relies on argv[0] to determine the name of an appropriate (1) kernel module pathname or (2) executable file pathname, which allows local users to gain privileges via an execl system call.
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Analysis
by VulDB Data Team • 12/31/2024
The vulnerability identified as CVE-2012-3485 affects Tunnelblick versions 3.3beta20 and earlier, presenting a critical privilege escalation risk through improper path resolution mechanisms. This flaw exploits the application's reliance on argv[0] for determining kernel module and executable file paths, creating a dangerous dependency that adversaries can manipulate to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability stems from the application's insecure handling of command-line arguments during the execl system call execution. When Tunnelblick processes user input through argv[0], it directly uses this parameter to construct file paths without adequate validation or sanitization. This design flaw allows local attackers to craft malicious command-line arguments that redirect the application to load unauthorized kernel modules or execute unintended binaries. The vulnerability specifically manifests when the application calls execl, which replaces the current process image with a new program, but does so using paths derived from untrusted argv[0 values.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential system compromise and persistent access. Local users with minimal privileges can leverage this weakness to gain root-level access, enabling them to modify system files, install backdoors, or exfiltrate sensitive data. The attack vector requires local system access but does not necessitate network connectivity, making it particularly dangerous in environments where local privilege escalation is not properly restricted. This vulnerability aligns with CWE-78 and CWE-787, representing command injection and out-of-bounds write issues respectively, while also mapping to ATT&CK technique T1068 which covers local privilege escalation through system binary manipulation.
Mitigation strategies for CVE-2012-3485 require immediate patching of affected Tunnelblick installations to versions 3.3beta21 or later, which address the path resolution logic by implementing proper input validation and using hardcoded, trusted paths instead of relying on argv[0. System administrators should also implement restrictive file permissions and execute regular security audits to identify similar vulnerabilities in other applications. Additionally, monitoring for suspicious execl system calls and implementing process integrity checks can help detect exploitation attempts. The vulnerability demonstrates the critical importance of avoiding dynamic path construction from untrusted input sources and underscores the necessity of following secure coding practices that prevent command injection attacks through proper argument validation and path resolution mechanisms.