CVE-2022-32470 is a high-severity vulnerability affecting InsydeH2O firmware versions with kernel versions 5.0 through 5.5. The vulnerability arises from a time-of-check to time-of-use (TOCTOU) race condition in the FwBlockServiceSmm shared buffer, which is used for communication between System Management Mode (SMM) and non-SMM code. Specifically, the vulnerability involves Direct Memory Access (DMA) attacks targeting the shared buffer used by the firmware block services. Because SMM operates at a highly privileged level with access to system management RAM (SMRAM), corruption of SMRAM through this race condition can lead to privilege escalation, allowing an attacker to execute arbitrary code at the highest privilege level on the system. The attack exploits the window between checking and using the data in the shared buffer, where malicious manipulation can occur. Mitigations include enabling Input-Output Memory Management Unit (IOMMU) protections to restrict DMA access to the ACPI runtime memory used for the command buffer, thereby preventing unauthorized DMA operations. Another mitigation is to copy the firmware block services data into SMRAM before performing validation checks, eliminating the race condition by ensuring the data used is not altered during processing. The vulnerability has a CVSS v3.1 base score of 7.0, indicating high severity, with attack vector local (requiring local access), high attack complexity, low privileges required, no user interaction, and impacts on confidentiality, integrity, and availability. No known exploits are currently reported in the wild. This vulnerability is classified under CWE-367 (Time-of-check Time-of-use Race Condition).

For European organizations, this vulnerability poses a significant risk because it allows local attackers with limited privileges to escalate their privileges to the highest system level by exploiting firmware-level flaws. This could lead to complete system compromise, including unauthorized access to sensitive data, disruption of critical services, and persistent malware implantation that is difficult to detect or remove. Organizations relying on devices with InsydeH2O firmware—commonly found in laptops, servers, and embedded systems—may face risks to data confidentiality, integrity, and availability. In sectors such as finance, healthcare, government, and critical infrastructure, where firmware integrity is crucial, exploitation could result in severe operational disruptions and data breaches. The requirement for local access limits remote exploitation but insider threats or attackers with physical or local network access could leverage this vulnerability. The lack of known exploits in the wild suggests limited immediate threat, but the high impact and complexity warrant proactive mitigation.

European organizations should implement the following specific mitigations: 1) Enable and properly configure IOMMU on all affected systems to restrict unauthorized DMA access, particularly to ACPI runtime memory regions. This requires verifying BIOS/UEFI settings and operating system support for IOMMU (e.g., Intel VT-d or AMD-Vi). 2) Work with hardware and firmware vendors to obtain and deploy firmware updates or patches that copy firmware block services data into SMRAM before validation, eliminating the TOCTOU race condition. 3) Conduct thorough inventory and asset management to identify devices running vulnerable InsydeH2O firmware versions and prioritize patching or mitigation on high-value or high-risk assets. 4) Implement strict local access controls and monitoring to detect and prevent unauthorized local access attempts, including physical security measures and endpoint detection solutions capable of identifying suspicious firmware-level activity. 5) Employ secure boot and firmware integrity verification mechanisms to detect unauthorized firmware modifications. 6) Educate IT and security teams about the risks of firmware vulnerabilities and the importance of layered defenses including hardware-based protections.