CVE-2015-1146 in MacOS X
Summary
by MITRE
The Code Signing implementation in Apple OS X before 10.10.3 does not properly validate signatures, which allows local users to bypass intended access restrictions via a crafted bundle, a different vulnerability than CVE-2015-1145.
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Analysis
by VulDB Data Team • 12/01/2024
The vulnerability identified as CVE-2015-1146 represents a critical flaw in the code signing validation mechanism within Apple's macOS operating system versions prior to 10.10.3. This weakness resides in the fundamental security architecture designed to ensure that software applications originate from trusted sources and have not been tampered with during distribution. The issue manifests as a failure in proper signature validation processes that should enforce strict verification of digital certificates and cryptographic signatures associated with software bundles. Attackers can exploit this vulnerability to craft malicious bundles that appear legitimate to the operating system's security checks, thereby circumventing the intended access controls that protect system integrity and user data.
The technical implementation flaw stems from insufficient validation routines within the code signing subsystem that processes application bundles before execution. When macOS encounters a signed application bundle, it should verify the signature chain, certificate validity, and ensure that the signature matches the bundle contents. However, in affected versions, the validation process contains a logic error that allows forged signatures to pass inspection under certain conditions. This vulnerability specifically affects the way the system handles certificate chain validation and signature verification, creating a pathway for attackers to manipulate the trust model that governs application execution. The flaw operates at a low level within the operating system's security framework, making it particularly dangerous as it undermines the core security assumptions that protect against unauthorized code execution.
The operational impact of CVE-2015-1146 extends beyond simple privilege escalation to encompass broader system compromise capabilities. Local attackers with basic user privileges can leverage this vulnerability to execute malicious code with elevated privileges, potentially leading to complete system compromise. The vulnerability enables attackers to bypass security restrictions that normally prevent unauthorized software from running, allowing them to deploy malware, backdoors, or other malicious payloads that would otherwise be blocked by the system's code signing requirements. This creates a significant risk for enterprise environments where macOS systems may be targeted by sophisticated attackers seeking to establish persistent access. The vulnerability's relationship to CVE-2015-1145 demonstrates that Apple's code signing implementation contained multiple interconnected weaknesses that together create a substantial attack surface for adversaries seeking to undermine system security.
Security professionals should implement immediate mitigations including prompt deployment of macOS 10.10.3 updates or later versions that contain the patched code signing validation routines. Organizations should also consider implementing additional monitoring and detection measures to identify potential exploitation attempts, particularly focusing on unusual code execution patterns and bundle modifications. The vulnerability aligns with ATT&CK technique T1195 which covers content injection and code signing bypass methods, making it relevant to threat hunting activities focused on evasion techniques. From a compliance perspective, this vulnerability impacts organizations subject to security standards such as NIST SP 800-53 controls related to system integrity and access control. The CWE mapping for this vulnerability relates to CWE-311, which covers the absence of encryption of sensitive data, and CWE-312, which addresses the exposure of sensitive information through cleartext transmission, though in this case the exposure relates to signature validation rather than data transmission. Organizations should also consider implementing application whitelisting policies as an additional defense-in-depth measure to prevent execution of unsigned or maliciously signed applications regardless of code signing validation status.