CVE-2023-31315 in 3rd Gen EPYC Processors
Summary
by MITRE • 08/12/2024
Improper validation in a model specific register (MSR) could allow a malicious program with ring0 access to modify SMM configuration while SMI lock is enabled, potentially leading to arbitrary code execution.
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Analysis
by VulDB Data Team • 12/11/2024
The vulnerability identified as CVE-2023-31315 represents a critical flaw in the management of model specific registers within x86 processor architectures. This weakness specifically targets the interaction between hardware-level model specific registers and the system management mode configuration, creating a pathway for privilege escalation attacks. The issue manifests when a malicious program operating at ring0 privileges attempts to manipulate SMM configuration parameters while the SMI lock mechanism remains enabled, effectively bypassing security controls designed to protect the most privileged execution environment.
The technical root cause of this vulnerability stems from inadequate validation mechanisms within the processor's model specific register handling routines. When SMI lock is enabled, the system should prevent modifications to critical SMM configuration registers that could compromise system integrity. However, the flawed validation logic allows unauthorized access to these registers, enabling attackers to modify SMM settings without proper authorization. This occurs because the processor fails to properly verify the legitimacy of register modifications during the SMM configuration process, creating a persistent backdoor that remains active even when other security measures are in place.
The operational impact of CVE-2023-31315 extends far beyond simple privilege escalation, as it fundamentally undermines the security model of modern computing systems. Attackers with ring0 access can leverage this vulnerability to execute arbitrary code within the SMM environment, which operates at the highest privilege level and is typically isolated from normal operating system protections. This capability enables sophisticated attacks that can persist across system reboots, modify system firmware, or establish covert communication channels that evade traditional security monitoring solutions. The vulnerability is particularly dangerous because SMM operates outside the normal operating system context, making it difficult for standard security tools to detect or prevent malicious activities within this privileged domain.
Security professionals should recognize this vulnerability as a variant of CWE-264, which addresses permissions, privileges, and access controls in processor-level operations. The attack vector aligns with techniques described in the ATT&CK framework under the privilege escalation and persistence tactics, specifically targeting the system management mode as a means to establish long-term control over affected systems. Mitigation strategies should include immediate firmware updates from processor manufacturers, implementation of runtime monitoring solutions capable of detecting unauthorized SMM register modifications, and enhanced system integrity verification procedures that can identify unauthorized changes to critical system configuration parameters. Organizations should also consider implementing hardware-based security features such as Intel's Control Flow Enforcement Technology or similar protections that can prevent unauthorized modifications to privileged execution contexts while maintaining system performance and compatibility.