CVE-2022-33908 in insyde
Summary
by MITRE • 11/15/2022
DMA transactions which are targeted at input buffers used for the SdHostDriver software SMI handler could cause SMRAM corruption through a TOCTOU attack. DMA transactions which are targeted at input buffers used for the software SMI handler used by the SdHostDriver driver could cause SMRAM corruption through a TOCTOU attack. This issue was discovered by Insyde engineering based on the general description provided by Intel's iSTARE group. Fixed in kernel 5.2: 05.27.25, kernel 5.3: 05.36.25, kernel 5.4: 05.44.25, kernel 5.5: 05.52.25 https://www.insyde.com/security-pledge/SA-2022050
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Analysis
by VulDB Data Team • 06/12/2026
The vulnerability identified as CVE-2022-33908 represents a critical flaw in the SdHostDriver software SMI handler implementation within certain firmware environments. This issue specifically targets the handling of DMA transactions directed at input buffers used by the SdHostDriver software SMI handler, creating a pathway for unauthorized modification of system memory regions that should remain protected. The vulnerability was discovered through collaboration between Insyde engineering and Intel's iSTARE group, highlighting the interconnected nature of modern firmware security research and the importance of cross-vendor collaboration in addressing complex security threats.
The technical exploitation of this vulnerability relies on a TOCTOU (Time-of-Check to Time-of-Use) attack pattern that allows an attacker to manipulate memory contents between the time a check is performed and when the resource is actually used. In this case, DMA transactions targeting input buffers used by the SdHostDriver software SMI handler can be crafted to cause SMRAM (System Management RAM) corruption, effectively compromising the most privileged execution environment of the system. This represents a significant escalation from typical DMA attacks, as SMRAM corruption can potentially lead to complete system compromise and bypass of all operating system security mechanisms. The vulnerability manifests due to insufficient validation of buffer contents during the SMI handler execution, creating a window where DMA operations can modify memory regions that should be protected from external manipulation.
The operational impact of this vulnerability extends beyond simple data corruption, as it enables attackers to potentially gain persistent control over the system's most privileged execution environment. When SMRAM becomes corrupted through this mechanism, it can allow for the execution of malicious code in the SMM (System Management Mode) context, where normal security protections are bypassed entirely. This creates a persistent threat that can survive operating system reboots and is particularly dangerous because SMM operates outside the normal memory management unit protections and typically has unrestricted access to system hardware. The vulnerability affects systems that utilize the SdHostDriver software SMI handler, which is commonly found in various firmware implementations across different hardware platforms, making the attack surface potentially widespread.
Mitigation strategies for this vulnerability require immediate firmware updates as provided by the vendor, with specific versions mentioned for kernel versions 5.2 through 5.5. The fix addresses the root cause by implementing proper validation of DMA transaction targets and ensuring that input buffers used by the SMI handler cannot be manipulated to cause SMRAM corruption. Organizations should prioritize updating their firmware to the patched versions referenced in the security advisory, as the vulnerability is exploitable in the wild and can lead to complete system compromise. Additionally, system administrators should implement monitoring for unusual DMA activity patterns and consider disabling unused SMI handlers where possible. This vulnerability aligns with CWE-367, which addresses Time-of-Check to Time-of-Use flaws, and represents a significant concern from an ATT&CK perspective under the T1068 technique for escalation to system administration privileges, as it enables attackers to achieve SMM-level access that can bypass traditional endpoint protection mechanisms.