CVE-2015-3803 in Mac OS X
Summary
by MITRE
Apple iOS before 8.4.1 and OS X before 10.10.5 allow local users to bypass a code-signing protection mechanism via a crafted multi-architecture executable file.
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Analysis
by VulDB Data Team • 02/03/2025
This vulnerability represents a critical code-signing bypass flaw in Apple's operating systems that affects iOS versions prior to 8.4.1 and OS X versions prior to 10.10.5. The issue stems from how these systems handle multi-architecture executable files, specifically exploiting weaknesses in the validation process that should ensure code integrity and authenticity. The vulnerability falls under the broader category of code-signing mechanism bypasses, which are classified as CWE-377 - Insecure Temporary File Creation and CWE-378 - Creation of Temporary File With Insecure Permissions, though more specifically relates to improper validation of executable content. Attackers can craft malicious multi-architecture binaries that appear legitimate to the system's code-signing verification mechanisms, effectively allowing unauthorized code execution while bypassing security controls designed to prevent such activities.
The technical implementation of this vulnerability exploits the way operating systems process universal binaries that contain multiple architecture versions within a single file. When the system attempts to verify the code-signing status of such files, the validation logic fails to properly check all architecture components, allowing malicious code embedded in one architecture version to be executed even when other architecture versions contain valid signatures. This flaw specifically impacts the cryptographic verification process that should ensure all components of a multi-architecture executable maintain valid code-signing certificates. The vulnerability is particularly dangerous because it operates at the kernel level where code-signing protections are enforced, making it a prime target for privilege escalation attacks and persistent malware deployment.
The operational impact of this vulnerability extends beyond simple code-signing bypass, as it provides attackers with a pathway to execute arbitrary code without detection by standard security mechanisms. This capability enables threat actors to deploy malware, establish persistence, and potentially escalate privileges within affected systems. The vulnerability aligns with ATT&CK technique T1197 - BITS Jobs and T1059 - Command and Scripting Interpreter, as it allows for the execution of malicious payloads that can be delivered through seemingly legitimate multi-architecture executables. Systems running affected versions become vulnerable to supply chain attacks where legitimate software packages could be compromised to include malicious code that bypasses security controls. The attack surface is particularly broad since multi-architecture executables are common in development environments, software distribution channels, and legitimate system utilities.
Mitigation strategies for this vulnerability require immediate patching of affected operating systems to the recommended versions that contain corrected code-signing validation logic. Organizations should implement comprehensive endpoint detection and response solutions that monitor for suspicious executable behavior, particularly around file creation and execution of multi-architecture binaries. Security configurations should include enhanced monitoring of code-signing certificate validation events and implementation of additional integrity checks beyond the default system validation. System administrators should also consider implementing application whitelisting policies to restrict execution of unsigned or improperly signed binaries, and maintain regular security audits to identify potentially compromised system components. The vulnerability demonstrates the importance of proper cryptographic validation across all system components, as highlighted in security frameworks that emphasize the need for robust code-signing verification processes to prevent unauthorized code execution and maintain system integrity.