CVE-2015-5945 in Mac OS X
Summary
by MITRE
The Sandbox subsystem in Apple OS X before 10.11.1 allows local users to gain privileges via vectors involving NVRAM parameters.
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Analysis
by VulDB Data Team • 11/21/2024
The vulnerability identified as CVE-2015-5945 represents a critical privilege escalation flaw within the Sandbox subsystem of Apple's macOS operating system. This issue affects versions prior to macOS 10.11.1 and specifically exploits weaknesses in how the system handles NVRAM (Non-Volatile Random Access Memory) parameters during the boot process. The Sandbox subsystem serves as a crucial security mechanism that restricts applications from accessing system resources and performing privileged operations, making this vulnerability particularly dangerous as it undermines fundamental security boundaries.
The technical exploitation occurs through improper validation of NVRAM parameters that are loaded during system initialization. When a local attacker can manipulate these parameters, they can bypass the sandbox restrictions and elevate their privileges to root level access. This flaw stems from insufficient input validation and improper parameter handling within the kernel-level components that manage NVRAM operations. The vulnerability allows attackers to inject malicious values into NVRAM that persist across reboots, creating a persistent backdoor mechanism. According to CWE classification, this maps to CWE-20: Improper Input Validation, specifically manifesting in kernel-level memory corruption scenarios where attacker-controlled data influences system behavior.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with complete system compromise capabilities. Once elevated to root privileges, malicious actors can install persistent malware, modify system files, access encrypted data, and establish covert communication channels without detection. The persistence aspect of this vulnerability is particularly concerning as NVRAM parameters typically survive system reboots, meaning the attacker's control remains intact even after system restarts. This characteristic aligns with ATT&CK technique T1547.001: Registry Run Keys / Startup Folder, though implemented through hardware-level persistence rather than software mechanisms. The vulnerability affects all macOS users who have not updated to version 10.11.1 or later, making it a widespread concern across enterprise and individual deployments.
Mitigation strategies for CVE-2015-5945 primarily focus on immediate system updates to macOS 10.11.1 or later versions where Apple has implemented proper NVRAM parameter validation and enhanced kernel security controls. System administrators should prioritize patch deployment across all affected macOS installations, particularly in enterprise environments where the risk of unauthorized access is highest. Additional protective measures include implementing hardware security modules for NVRAM protection, monitoring system boot processes for unauthorized parameter changes, and maintaining comprehensive audit logs of system modifications. The vulnerability highlights the importance of kernel-level security controls and demonstrates how low-level system components can create significant security risks when proper input validation and access controls are not implemented. Organizations should also consider implementing network-based intrusion detection systems to monitor for potential exploitation attempts and establish incident response procedures specifically addressing kernel-level privilege escalation attacks.