CVE-2009-2811 in Mac OS X
Summary
by MITRE
Incomplete blacklist vulnerability in Launch Services in Apple Mac OS X 10.5.8 allows user-assisted remote attackers to execute arbitrary code via a .fileloc file, which does not trigger a "potentially unsafe" warning message in the Quarantine feature.
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Analysis
by VulDB Data Team • 03/30/2025
The vulnerability described in CVE-2009-2811 represents a critical security flaw within Apple Mac OS X 10.5.8's Launch Services component that demonstrates a failure in proper input validation and security policy enforcement. This issue stems from an incomplete blacklist implementation that fails to adequately restrict the execution of potentially malicious file types through the Quarantine feature, which is designed to warn users about downloaded files that may pose security risks. The vulnerability specifically affects the handling of .fileloc files, which are used by macOS to store file location information and are typically processed by the system's Launch Services framework to determine how to open or execute files.
The technical flaw manifests in the Launch Services subsystem's inability to properly identify and block .fileloc files that contain malicious payloads or point to harmful executables. When a user encounters such a file, the Quarantine feature fails to display the expected "potentially unsafe" warning message that would normally alert the user to the security risk. This incomplete blacklist mechanism allows attackers to craft .fileloc files that bypass the system's security checks, effectively enabling a user-assisted remote code execution attack vector. The vulnerability operates at the system integration layer where file type associations and execution policies are enforced, making it particularly dangerous as it leverages legitimate system functionality to execute unauthorized code.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally undermines the security model of macOS 10.5.8 by allowing attackers to circumvent the quarantine protection mechanism. This creates a scenario where users may unknowingly execute malicious code through seemingly benign file location references, particularly when these files are obtained through email attachments, web downloads, or removable media. The user-assisted nature of the attack means that social engineering plays a crucial role in exploitation, as users must be convinced to open the malicious .fileloc files, but the underlying flaw removes the security warning that would typically prevent such actions. This vulnerability aligns with CWE-20, which describes improper input validation, and demonstrates how incomplete security controls can lead to privilege escalation and arbitrary code execution.
Security mitigations for this vulnerability require both immediate system updates and operational procedures to address the incomplete blacklist implementation. Apple's subsequent release of security patches would have focused on strengthening the Quarantine feature's file type validation and ensuring that .fileloc files are properly analyzed for potential security threats. Organizations should implement additional monitoring of file associations and execution patterns, particularly around .fileloc files, while users need to be educated about the risks of opening untrusted files even when no warning messages appear. The remediation process should include verifying that the system's Launch Services framework properly enforces security policies and that all file type handlers are correctly configured to prevent unauthorized execution. This vulnerability highlights the importance of comprehensive security testing and the need for robust input validation mechanisms, as outlined in the ATT&CK framework's techniques for privilege escalation and execution. The issue also demonstrates how seemingly minor security gaps in system components can create significant attack vectors, emphasizing the critical nature of maintaining complete and up-to-date security controls across all system layers.