CVE-2021-32015 in NPCT75x
Summary
by MITRE • 06/08/2021
In Nuvoton NPCT75x TPM 1.2 firmware 7.4.0.0, a local authenticated malicious user with high privileges could potentially gain unauthorized access to TPM non-volatile memory. NOTE: Upgrading to firmware version 7.4.0.1 will mitigate against the vulnerability, but version 7.4.0.1 is not TCG or Common Criteria (CC) certified. Nuvoton recommends that users apply the NPCT75x TPM 1.2 firmware update.
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Analysis
by VulDB Data Team • 06/11/2021
The vulnerability identified as CVE-2021-32015 affects the Nuvoton NPCT75x TPM 1.2 firmware version 7.4.0.0, representing a critical security flaw that undermines the integrity of trusted platform module operations. This issue specifically targets the non-volatile memory subsystem within the TPM implementation, creating potential pathways for unauthorized data access that could compromise the fundamental security assurances provided by the TPM. The vulnerability manifests when an authenticated user with high privileges attempts to exploit weaknesses in the firmware's memory protection mechanisms, potentially allowing access to sensitive cryptographic keys, certificates, and other confidential data stored within the TPM's persistent storage.
The technical implementation flaw stems from inadequate access control mechanisms within the firmware's memory management system, where proper authorization checks fail to adequately protect the non-volatile memory segments. This weakness aligns with CWE-284, which addresses improper access control vulnerabilities, and represents a direct violation of the TPM specification's requirements for maintaining data confidentiality and integrity. The flaw allows for privilege escalation through authenticated channels, where a malicious actor with elevated system privileges can bypass normal access restrictions and directly read or modify the TPM's persistent storage areas. This represents a significant deviation from the TPM 1.2 specification's security model, which mandates that non-volatile memory be protected against unauthorized access even from authenticated users.
The operational impact of this vulnerability extends beyond simple data exposure, as it fundamentally compromises the trust model that TPMs are designed to establish. When an attacker gains access to the TPM's non-volatile memory, they can potentially extract cryptographic keys, certificates, and other sensitive data that would normally remain protected. This access could enable sophisticated attacks including key recovery, certificate forgery, and complete compromise of the platform's cryptographic security infrastructure. The vulnerability affects systems where the TPM serves as a core security component for hardware-based authentication, secure boot processes, and cryptographic operations, potentially enabling attackers to bypass hardware-level security measures and gain deeper system access.
The recommended mitigation strategy involves upgrading to firmware version 7.4.0.1, which addresses the specific access control weaknesses identified in the vulnerability. However, this remediation introduces additional considerations as the updated firmware version lacks TCG or Common Criteria certification, potentially limiting its deployment in regulated environments where formal security validation is required. Organizations must carefully evaluate the trade-offs between immediate security remediation and compliance requirements when implementing this update. The vulnerability highlights the importance of maintaining current firmware versions and the risks associated with deploying uncertified security updates in enterprise environments. Security teams should implement comprehensive monitoring to detect potential exploitation attempts and establish procedures for firmware validation and deployment that consider both security requirements and compliance obligations.
This vulnerability demonstrates the critical importance of proper firmware security management and the potential risks associated with embedded security components that may not undergo the same rigorous validation processes as other security solutions. The attack vector requires local authentication and high privileges, making it less likely to be exploited remotely but still represents a significant threat in environments where privileged access is compromised. The remediation approach underscores the need for continuous security assessment and the importance of vendor security updates even when they may not meet all certification requirements. Organizations should establish robust firmware update policies that balance security requirements with operational constraints while maintaining awareness of the certification status of security patches and updates.