CVE-2022-32470 in InsydeH2O
Summary
by MITRE • 02/15/2023
An issue was discovered in Insyde InsydeH2O with kernel 5.0 through 5.5. DMA attacks on the FwBlockServiceSmm shared buffer used by SMM and non-SMM code could cause TOCTOU race-condition issues that could lead to corruption of SMRAM and escalation of privileges. This attack can be mitigated using IOMMU protection for the ACPI runtime memory used for the command buffer. This attack can be mitigated by copying the firmware block services data to SMRAM before checking it.
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Analysis
by VulDB Data Team • 05/29/2026
The vulnerability identified as CVE-2022-32470 represents a critical security flaw within the Insyde InsydeH2O firmware implementation, specifically affecting kernel versions 5.0 through 5.5. This issue manifests as a time-of-check to time-of-use race condition that occurs within the Firmware Block Service Shared Buffer mechanism utilized by System Management Mode (SMM) and standard mode code. The flaw exists in the interaction between SMM and non-SMM execution contexts, creating an exploitable window where malicious actors can manipulate shared memory structures during critical operations.
The technical exploitation of this vulnerability involves DMA attacks against the FwBlockServiceSmm shared buffer, which operates in a manner that violates fundamental security principles established by the Common Weakness Enumeration standard CWE-367. The race condition occurs when SMM code performs a check on firmware block service data and subsequently uses that same data without re-validation, allowing an attacker to modify the buffer contents between the check and use operations. This creates a window of opportunity for privilege escalation and potential SMRAM corruption, as the shared buffer serves as a critical communication channel between privileged and non-privileged execution contexts.
The operational impact of this vulnerability extends beyond simple privilege escalation to include complete system compromise and potential data exfiltration. Attackers leveraging this flaw can gain access to SMRAM, which contains sensitive system information and cryptographic keys, effectively breaking the fundamental security boundaries that separate normal operating system execution from the protected SMM environment. This vulnerability directly maps to the ATT&CK technique T1068, which describes the use of privilege escalation to gain access to protected system resources. The attack vector through DMA capabilities also aligns with ATT&CK technique T1084, representing an attack path that utilizes hardware-level access to compromise system security.
The mitigation strategies recommended for this vulnerability include implementing IOMMU protection for the ACPI runtime memory used in command buffer operations, which directly addresses the underlying DMA attack surface by creating memory protection boundaries that prevent unauthorized access to critical firmware buffers. Additionally, the suggested approach of copying firmware block services data to SMRAM before validation provides a software-based defense that eliminates the race condition by ensuring that the data used in critical operations remains consistent throughout the execution sequence. These mitigations align with the principle of least privilege and defense in depth as outlined in various cybersecurity frameworks, including NIST SP 800-53 and ISO 27001 standards, which emphasize the importance of protecting critical system resources through both hardware and software controls to prevent unauthorized access and privilege escalation attacks.