CVE-2022-33984 is a high-severity vulnerability involving a Time-Of-Check to Time-Of-Use (TOCTOU) race condition in the handling of Direct Memory Access (DMA) transactions targeting input buffers used by the SdMmcDevice software System Management Interrupt (SMI) handler. Specifically, the vulnerability arises when DMA transactions access input buffers that the SdMmcDevice driver’s software SMI handler uses, potentially causing corruption of the System Management RAM (SMRAM). SMRAM is a highly privileged memory region used by the system firmware to execute System Management Mode (SMM) code, which operates at a higher privilege level than the operating system and is responsible for critical system functions such as power management and hardware control. Corruption of SMRAM can lead to arbitrary code execution at the highest privilege level, compromising system integrity and confidentiality. The issue was discovered by Insyde engineering based on Intel’s iSTARE group’s general description and affects multiple kernel versions, with fixes applied in kernel 5.2 (05.27.25), 5.3 (05.36.25), 5.4 (05.44.25), and 5.5 (05.52.25). The vulnerability is classified under CWE-367 (Time-of-check Time-of-use race condition) and has a CVSS v3.1 score of 7.0, indicating high severity. The attack vector requires local access (AV:L), high attack complexity (AC:H), low privileges (PR:L), and no user interaction (UI:N). Exploitation could result in complete compromise of confidentiality, integrity, and availability of the affected system. No known exploits are currently reported in the wild. The vulnerability affects systems using the SdMmcDevice driver and software SMI handlers that process DMA transactions, which are common in platforms utilizing System Management Mode and related firmware components.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and critical infrastructure relying on hardware platforms that use the affected kernel versions and firmware components. Successful exploitation could allow attackers with local access to execute arbitrary code in System Management Mode, bypassing operating system security controls and potentially leading to full system compromise. This could result in theft of sensitive data, disruption of critical services, and persistent firmware-level malware infections that are difficult to detect and remediate. Sectors such as finance, healthcare, telecommunications, and government agencies in Europe, which often use enterprise-grade hardware and have stringent security requirements, could be particularly impacted. Additionally, organizations with remote or hybrid workforces might face increased risk if attackers gain local access through compromised endpoints. The high privilege level of the vulnerability means that traditional endpoint security solutions may be ineffective against attacks exploiting this flaw, increasing the potential impact on confidentiality, integrity, and availability of critical systems.

To mitigate this vulnerability, European organizations should prioritize the following actions: 1) Apply the vendor-provided patches and firmware updates that address this vulnerability, specifically upgrading to kernel versions 5.2 (05.27.25), 5.3 (05.36.25), 5.4 (05.44.25), or 5.5 (05.52.25) or later as applicable. 2) Conduct thorough inventory and assessment of hardware and software platforms to identify systems running affected kernel versions and SdMmcDevice drivers. 3) Restrict local access to sensitive systems by enforcing strict physical security controls and limiting administrative privileges to trusted personnel only. 4) Implement monitoring for unusual DMA transactions or anomalous behavior related to System Management Mode, leveraging hardware-based security features where available. 5) Employ endpoint detection and response (EDR) solutions capable of detecting low-level firmware attacks and integrate firmware integrity checks into security operations. 6) Educate IT and security teams about the risks associated with firmware-level vulnerabilities and the importance of timely patch management. 7) Coordinate with hardware vendors and firmware providers to ensure ongoing updates and security advisories are promptly addressed. These measures go beyond generic advice by emphasizing firmware-level security, physical access controls, and advanced monitoring tailored to the nature of this vulnerability.