CVE-2022-32475 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 VariableRuntimeDxe 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 issue was fixed in the kernel, which also protected chipset and OEM chipset code.
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Analysis
by VulDB Data Team • 05/29/2026
The vulnerability identified as CVE-2022-32475 affects Insyde InsydeH2O firmware implementations running kernel versions 5.0 through 5.5, representing a critical security flaw that undermines the integrity of System Management Mode operations. This issue stems from improper handling of shared memory buffers between SMM and non-SMM execution contexts, creating a dangerous attack surface for sophisticated adversaries. The vulnerability specifically targets the VariableRuntimeDxe shared buffer mechanism, which serves as a communication channel between different firmware execution modes and is fundamental to proper system operation.
The technical flaw manifests as a time-of-check to time-of-use race condition that occurs during DMA operations on the shared buffer. When malicious actors perform DMA attacks against the VariableRuntimeDxe buffer, they can exploit the temporal gap between when the system validates buffer access permissions and when the actual memory operations occur. This race condition allows attackers to manipulate memory contents while the system is in the process of validating access, potentially corrupting the System Management RAM that is supposed to remain protected from normal operating system access. The vulnerability is classified under CWE-367, which specifically addresses Time-of-Check to Time-of-Use race conditions, making it particularly dangerous as it enables privilege escalation attacks that can bypass traditional security boundaries.
The operational impact of this vulnerability extends beyond simple data corruption, as it enables attackers to gain unauthorized access to SMRAM memory regions that should remain isolated from normal system operations. This represents a fundamental breach in the security architecture of the firmware, allowing attackers to potentially execute arbitrary code with the highest privilege levels available to the system. The threat is particularly severe because it operates at the firmware level, where traditional operating system security controls are ineffective. Attackers could leverage this vulnerability to install rootkits, modify system firmware, or extract sensitive cryptographic keys that are typically protected within SMRAM. The vulnerability affects not just the base firmware but also chipset and OEM implementations that rely on the same shared buffer mechanisms.
Mitigation strategies for this vulnerability require immediate firmware updates from vendors, as the fix was implemented directly within the kernel components. System administrators should prioritize updating to firmware versions that address this specific race condition in the VariableRuntimeDxe buffer handling. Additionally, organizations should implement hardware-based security measures such as memory protection units and DMA protection features where available. The fix addresses the core issue by implementing proper synchronization mechanisms and access controls that prevent the race condition from occurring during DMA operations. Security monitoring should focus on detecting unusual DMA activity patterns and unauthorized buffer access attempts, as these could indicate exploitation attempts. The vulnerability highlights the importance of proper firmware security practices and demonstrates how seemingly minor implementation flaws in shared memory handling can create significant security risks for entire computing platforms. Organizations should also consider implementing microcode updates from chipset vendors and ensuring that all firmware components maintain consistent security standards across different OEM implementations.