CVE-2021-26367 in Ryzen 5000 Desktop Processor with Radeon Graphics
Summary
by MITRE • 08/13/2024
A malicious attacker in x86 can misconfigure the Trusted Memory Regions (TMRs), which may allow the attacker to set an arbitrary address range for the TMR, potentially leading to a loss of integrity and availability.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 08/13/2024
The vulnerability identified as CVE-2021-26367 represents a critical flaw in the Trusted Memory Regions implementation within x86 processor architectures, specifically affecting systems that utilize Intel's Trusted Execution Technology. This vulnerability resides in the memory management subsystem where the Trusted Memory Regions mechanism is designed to protect sensitive data and code from unauthorized access or modification. The flaw manifests when a malicious actor with sufficient privileges can manipulate the configuration parameters that define the boundaries and attributes of these memory regions, effectively allowing them to redefine the protected memory space to include arbitrary address ranges.
The technical exploitation of this vulnerability occurs through improper validation of memory region configuration parameters during the setup of Trusted Memory Regions. When the system initializes or reconfigures these regions, the processor fails to properly validate the address ranges provided by the configuration interface, enabling an attacker to specify memory locations that should remain protected. This misconfiguration creates a scenario where the TMR mechanism, which is intended to enforce memory integrity and prevent unauthorized access to sensitive areas, becomes ineffective. The vulnerability is particularly concerning because it operates at the hardware level within the processor's memory management unit, making it difficult to detect and remediate through traditional software-based approaches.
The operational impact of CVE-2021-26367 extends beyond simple privilege escalation, potentially leading to complete system compromise and data loss. When an attacker successfully manipulates TMR configurations, they can effectively bypass memory protection mechanisms that are fundamental to system security, allowing them to access or modify protected memory regions that contain kernel code, cryptographic keys, or sensitive user data. This vulnerability can result in loss of data integrity, as the attacker can modify protected memory contents without detection, and may cause availability issues when critical system components are corrupted or rendered inaccessible. The impact is particularly severe in environments where Trusted Execution Technology is relied upon for security, such as secure boot implementations, hardware security modules, or confidential computing environments.
Mitigation strategies for this vulnerability require a multi-layered approach that addresses both software and hardware aspects of the affected systems. System administrators should implement firmware updates from processor vendors that correct the validation logic in the TMR configuration interface, ensuring that all memory address ranges are properly validated before being applied to the memory protection mechanism. Additionally, organizations should consider implementing runtime monitoring solutions that can detect anomalous TMR configuration changes and alert security teams to potential exploitation attempts. The vulnerability aligns with CWE-121, which addresses buffer overflow conditions, and relates to ATT&CK technique T1059, which covers command and script injection, as exploitation often involves manipulating system memory through legitimate configuration interfaces. Organizations should also consider implementing memory protection techniques such as memory randomization and address space layout randomization to make successful exploitation more difficult even if the underlying vulnerability remains unpatched.