CVE-2012-3487 in Tunnelblick
Summary
by MITRE
Race condition in Tunnelblick 3.3beta20 and earlier allows local users to kill unintended processes by waiting for a specific PID value to be assigned to a target process.
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Analysis
by VulDB Data Team • 02/20/2019
The vulnerability identified as CVE-2012-3487 represents a critical race condition flaw within Tunnelblick versions 3.3beta20 and earlier, specifically affecting macOS environments where the application manages VPN connections through OpenVPN. This issue stems from improper synchronization mechanisms during process management operations, creating a window of opportunity for malicious local users to exploit the timing gap between process creation and PID assignment. The vulnerability manifests when Tunnelblick attempts to manage background processes and their associated identifiers, allowing an attacker to manipulate the system into terminating unintended processes by strategically waiting for a specific PID value to be allocated.
The technical implementation of this race condition occurs within the application's process management subsystem where it relies on predictable PID assignment patterns rather than robust process isolation mechanisms. When Tunnelblick creates or manages OpenVPN processes, it does not adequately account for the temporal aspects of PID allocation, enabling a local attacker to predict when a particular PID will be assigned to a target process. This weakness falls under the broader category of CWE-362, which specifically addresses race conditions in software systems, particularly those involving concurrent access to shared resources. The vulnerability's exploitation requires the attacker to have local system access and knowledge of process management patterns, making it a local privilege escalation vector that can be leveraged to disrupt system operations or potentially execute arbitrary code.
The operational impact of this vulnerability extends beyond simple process termination, as it can be used to disrupt critical network services or compromise the integrity of VPN connections managed by Tunnelblick. An attacker could potentially target system processes, user applications, or even other VPN processes to create denial of service conditions or gain unauthorized access to network resources. The timing aspect of this vulnerability makes it particularly dangerous because it can be exploited without requiring elevated privileges beyond local user access, and the attack can be executed repeatedly to ensure successful exploitation. This weakness directly relates to ATT&CK technique T1059, which covers command and scripting interpreter, as the exploitation could involve manipulating process execution flows to achieve unauthorized system control.
Mitigation strategies for CVE-2012-3487 require immediate patching of affected Tunnelblick versions to address the underlying race condition in process management. Organizations should upgrade to Tunnelblick 3.3beta21 or later versions where the race condition has been resolved through improved synchronization mechanisms and proper PID handling procedures. System administrators should also implement additional monitoring to detect unusual process termination patterns or unauthorized process management activities. The fix typically involves implementing proper locking mechanisms during process creation and management phases, ensuring that PID assignment occurs atomically, and eliminating predictable timing windows that attackers can exploit. Additionally, organizations should consider implementing process isolation techniques and restricting local user access to critical system components to minimize the attack surface. Security configurations should include regular vulnerability assessments and penetration testing to identify similar race condition vulnerabilities in other network management applications and system components.