CVE-2016-8103 in NUC Kit
Summary
by MITRE
SMM call out in all Intel Branded NUC Kits allows a local privileged user to access the System Management Mode and take full control of the platform.
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Analysis
by VulDB Data Team • 08/24/2019
The vulnerability identified as CVE-2016-8103 represents a critical flaw in Intel NUC (Next Unit of Computing) kits that affects the System Management Mode execution environment. This vulnerability specifically targets the System Management Mode call out mechanism present in all Intel-branded NUC kits, creating a pathway for exploitation that can compromise the entire platform security. The issue stems from improper access controls within the system management subsystem, allowing unauthorized local users with privileged access to gain entry into the System Management Mode where they can execute arbitrary code with the highest level of privileges available to the system.
The technical flaw manifests through a weakness in the System Management Mode implementation that fails to properly validate the privileges of callers attempting to access the SMM environment. This vulnerability is classified under CWE-284 which addresses improper access control, specifically in the context of system management mode operations. The flaw allows a local privileged user to leverage the SMM call out mechanism to transition from user mode to system management mode without proper authentication or authorization checks, effectively bypassing the normal security boundaries that should protect the most critical system components.
From an operational impact perspective, this vulnerability presents a severe risk to system integrity and confidentiality as it enables attackers to gain complete control over the platform. Once inside the System Management Mode, an attacker can modify system firmware, intercept system calls, manipulate hardware components, and potentially establish persistent backdoors that survive operating system reboots. The attack surface is particularly concerning because the SMM environment operates with the highest privilege level in the system, making it a prime target for attackers seeking to establish persistent access or to perform advanced persistent threats against the platform. This vulnerability undermines the fundamental security model of modern computing systems where SMM is designed to be a trusted execution environment.
The mitigation strategies for CVE-2016-8103 primarily involve firmware updates from Intel that address the improper access control in the SMM call out mechanism. Organizations should immediately apply the latest firmware updates provided by Intel to address this vulnerability, as these patches typically include enhanced access control checks and proper validation of caller privileges before allowing SMM transitions. Additionally, system administrators should implement strict access controls and monitor for unusual system behavior that might indicate exploitation attempts. The vulnerability aligns with ATT&CK technique T1068 which covers the use of local privilege escalation to gain system-level access, and T1543 which involves the use of system services to maintain persistence. Regular security assessments and monitoring of system management mode activities should be implemented as part of comprehensive security controls to detect potential exploitation attempts and ensure the continued integrity of the platform's security architecture.