CVE-2014-4391

Vulnerability

CVE-2014-4391 is a vulnerability in the Code Signing feature of Apple OS X versions prior to 10.10 Yosemite. The bug occurs when the system processes signed application bundles with incomplete resource envelopes. Specifically, if an attacker omits an execution-related resource from the envelope, the operating system fails to properly validate the bundle's integrity, allowing the bundle to be signed with seemingly valid credentials while missing critical execution resources [1].

Exploitation

An attacker can exploit this vulnerability by crafting a signed bundle that deliberately omits an execution-related resource. The attacker must then convince the target user to download and open this malicious bundle, typically through social engineering (e.g., a phishing email or malicious website). No additional authentication or privileged network position is required beyond user interaction. The attack does not require the attacker to have valid code signing certificates because the system accepts the incomplete envelope as valid [1].

Impact

Successful exploitation allows a remote attacker to bypass the intended app-author restrictions enforced by OS X's Code Signing mechanism. This means the attacker can execute arbitrary code without the user being warned that the application has been tampered with or is missing required components. The impact is a compromise of the application's integrity and the system's security policy, potentially leading to full system compromise depending on the malicious bundle's payload [1].

Mitigation

Apple addressed CVE-2014-4391 in OS X Yosemite v10.10. Users should upgrade to OS X 10.10 or later to receive the fix. No workarounds are available for affected versions prior to 10.10. This vulnerability is not listed on the CISA Known Exploited Vulnerabilities (KEV) catalog as of the publication date [1].