CVE-2020-12946 in EPYC
Summary
by MITRE • 11/17/2021
Insufficient input validation in PSP firmware for discrete TPM commands could allow a potential loss of integrity and denial of service.
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Analysis
by VulDB Data Team • 11/19/2021
The vulnerability identified as CVE-2020-12946 resides within the Platform Security Processor firmware of certain Intel systems, specifically affecting the discrete TPM command processing mechanisms. This weakness stems from inadequate validation of input parameters provided to TPM commands, creating a potential attack surface that could be exploited by malicious actors to compromise system integrity. The PSP firmware serves as a critical security component responsible for managing hardware-level security functions including TPM operations, making this vulnerability particularly concerning for enterprise and government deployments where hardware security is paramount.
The technical flaw manifests in the insufficient sanitization and validation of command parameters passed to the TPM interface within the PSP firmware environment. When discrete TPM commands are received, the firmware fails to properly validate the input data structures, potentially allowing malformed or unexpected parameters to be processed without adequate safeguards. This weakness enables attackers to craft specially crafted TPM commands that could bypass normal security checks and validation routines. The vulnerability operates at the firmware level, making it particularly difficult to detect and remediate as it exists below the operating system layer where traditional security controls may not be effective.
The operational impact of this vulnerability extends beyond simple integrity compromise to include potential denial of service conditions that could render security functions unavailable. Attackers exploiting this weakness could potentially cause the TPM to malfunction or crash, leading to complete loss of TPM functionality and undermining the entire hardware security infrastructure. This could result in failed secure boot processes, compromised key storage, and overall system security degradation. The vulnerability particularly affects systems where the PSP firmware manages critical security operations including trusted platform module functionality, secure key management, and hardware-based authentication mechanisms. Organizations utilizing systems with discrete TPM capabilities face significant risk as this vulnerability could enable attackers to escalate privileges and gain unauthorized access to protected system resources.
Mitigation strategies for CVE-2020-12946 should focus on firmware updates provided by vendors, as this vulnerability requires modifications to the PSP firmware itself to address the insufficient input validation mechanisms. System administrators should prioritize applying vendor patches and firmware updates as soon as they become available, particularly in environments where hardware security is critical. Additional defensive measures include monitoring TPM command execution logs for anomalous patterns, implementing network segmentation to limit access to systems with discrete TPM capabilities, and maintaining robust backup and recovery procedures for systems where TPM integrity is essential. The vulnerability aligns with CWE-20, which describes improper input validation, and represents a specific instance of how firmware-level security flaws can create persistent threats that are difficult to detect and remediate. Organizations should also consider implementing hardware security modules and alternative authentication mechanisms as compensating controls while awaiting full patch deployment. This vulnerability demonstrates the critical importance of firmware security in modern computing environments and the need for comprehensive security testing at all levels of the system architecture.