CVE-2022-35893 is a high-severity vulnerability affecting InsydeH2O firmware versions with kernel 5.0 through 5.5. The vulnerability exists in the FvbServicesRuntimeDxe driver, which operates within the System Management Mode (SMM) of the firmware. Specifically, it is an SMM memory corruption issue that allows an attacker to write fixed or predictable data into SMRAM (System Management RAM). SMRAM is a highly privileged memory region used exclusively by SMM code, which runs at a higher privilege level than the operating system and is responsible for critical system functions such as power management and hardware control. By corrupting SMRAM, an attacker can escalate privileges to SMM, effectively gaining control over the system at the highest privilege level. The vulnerability is characterized by CWE-20 (Improper Input Validation), indicating that the driver does not properly validate inputs, enabling memory corruption. The CVSS v3.1 base score is 8.2, reflecting high impact on confidentiality, integrity, and availability, with an attack vector requiring local access (AV:L), low attack complexity (AC:L), high privileges (PR:H), no user interaction (UI:N), and scope change (S:C). Exploitation would require an attacker to have already obtained high privileges on the system, but successful exploitation could lead to complete system compromise by gaining SMM privileges. No known exploits are currently reported in the wild, and no patches are linked, indicating that mitigation may rely on vendor firmware updates or other protective measures. This vulnerability is critical because SMM compromise undermines all OS-level security controls and can be used to install persistent, stealthy malware that is difficult to detect or remove.

For European organizations, this vulnerability poses a significant risk, especially for enterprises and government agencies relying on devices with InsydeH2O firmware versions 5.0 to 5.5. Successful exploitation could lead to full system compromise, enabling attackers to bypass OS security, access sensitive data, and maintain persistent control over affected devices. This is particularly concerning for sectors handling critical infrastructure, finance, healthcare, and defense, where confidentiality and integrity of data are paramount. The local attack vector and requirement for high privileges mean that initial access must be obtained through other means (e.g., phishing, insider threat, or other vulnerabilities), but once foothold is established, this vulnerability could be leveraged to escalate privileges to the highest level. This could facilitate advanced persistent threats (APTs) and sophisticated espionage campaigns targeting European organizations. Additionally, the stealthy nature of SMM-level malware complicates detection and remediation, increasing potential downtime and recovery costs.

1. Immediate mitigation involves verifying firmware versions on all devices and identifying those running InsydeH2O kernel versions 5.0 through 5.5. 2. Coordinate with hardware vendors and Insyde to obtain firmware updates or patches addressing this vulnerability; prioritize deployment in high-risk environments. 3. Implement strict access controls and monitoring to prevent unauthorized local access, as exploitation requires local high privileges. 4. Employ endpoint detection and response (EDR) solutions capable of monitoring for anomalous behavior indicative of privilege escalation attempts, although detection at SMM level is challenging. 5. Harden systems by disabling unnecessary services and drivers that could be leveraged to gain initial access or escalate privileges. 6. Conduct regular security audits and penetration testing focusing on firmware and low-level components. 7. Educate IT and security teams about the risks of firmware vulnerabilities and the importance of timely patching. 8. Where possible, enable hardware-based security features such as Intel Boot Guard or TPM protections that can help detect or prevent unauthorized firmware modifications. 9. Maintain an inventory of devices and their firmware versions to quickly respond to emerging threats.