CVE-2022-31243 in insyde
Summary
by MITRE • 11/15/2022
Update description and links DMA transactions which are targeted at input buffers used for the software SMI handler used by the FvbServicesRuntimeDxe driver 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 FvbServicesRuntimeDxe driver could cause SMRAM corruption. This issue was discovered by Insyde engineering based on the general description provided by Intel's iSTARE group. Fixed in Kernel 5.2: 05.27.21. Kernel 5.3: 05.36.21. Kernel 5.4: 05.44.21. Kernel 5.5: 05.52.21 https://www.insyde.com/security-pledge/SA-2022044
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Analysis
by VulDB Data Team • 05/01/2025
The vulnerability identified as CVE-2022-31243 represents a critical security flaw in the firmware implementation of the FvbServicesRuntimeDxe driver, which operates within the UEFI runtime environment. This issue stems from improper handling of DMA transactions targeting input buffers used by the software SMI (System Management Interrupt) handler, creating a significant attack surface that could lead to complete system compromise. The vulnerability was discovered through collaboration between Insyde engineering and Intel's iSTARE group, highlighting the interconnected nature of firmware security research across major technology vendors.
The technical flaw manifests through a TOCTOU (Time-of-Check to Time-of-Use) attack pattern where malicious DMA operations can manipulate input buffers during the software SMI handler execution. This specific vulnerability occurs within the FvbServicesRuntimeDxe driver's runtime services, which are responsible for flash vector block services and provide runtime access to firmware volumes. When DMA transactions target these input buffers, they can corrupt the SMRAM (System Management RAM) memory space, which is protected from normal system operations but accessible during SMI execution. The flaw essentially allows an attacker to manipulate data structures that are expected to remain consistent between the time of validation and actual processing, creating a window for memory corruption attacks.
The operational impact of this vulnerability extends beyond simple data corruption, as SMRAM corruption can enable attackers to gain complete control over the system's firmware runtime environment. This represents a severe threat to system integrity since SMRAM is designed to be protected from normal system memory access and typically contains critical firmware code and data structures. Attackers could potentially execute arbitrary code within the SMM (System Management Mode) context, which operates with the highest privilege level and can bypass normal operating system security controls. The vulnerability affects multiple kernel versions, with fixes implemented across Kernel 5.2 through 5.5, indicating this was a widespread issue affecting various Linux kernel implementations.
The attack vector for this vulnerability requires an attacker to have the ability to perform DMA operations against system memory, which can be achieved through various means including malicious hardware devices, compromised USB peripherals, or other DMA-capable components. This aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and specifically addresses the use of DMA attacks against system firmware. The vulnerability also relates to CWE-367 which describes Time-of-Check to Time-of-Use (TOCTOU) flaws, where the state of a resource changes between when it's checked and when it's used, allowing for exploitation. This flaw demonstrates how firmware-level vulnerabilities can bypass traditional security controls and provides a pathway for attackers to achieve persistent, stealthy system compromise through the firmware layer.
Mitigation strategies for this vulnerability should focus on implementing proper DMA protection mechanisms, including enabling IOMMU (Input-Output Memory Management Unit) support, disabling unnecessary DMA capabilities, and ensuring that firmware updates are applied promptly. System administrators should also consider implementing hardware-level protections such as Intel's VT-d or AMD-Vi technologies to prevent unauthorized DMA operations. The fix implemented in kernel versions from 5.2 through 5.5 addresses the root cause by properly synchronizing buffer access during SMI handler execution and preventing the TOCTOU conditions that enabled the corruption. Organizations should also conduct regular firmware security assessments and maintain updated firmware repositories to ensure complete protection against similar vulnerabilities in their infrastructure.