CVE-2022-35895 is a high-severity vulnerability affecting the Insyde InsydeH2O firmware, specifically in versions of the kernel from 5.0 through 5.5. The vulnerability resides in the FwBlockSericceSmm driver, which handles software System Management Interrupt (SMI) routines. The core issue is improper validation of input parameters passed to this driver, which leads to memory corruption at arbitrary addresses, including the System Management RAM (SMRAM). SMRAM is a highly privileged memory region used by the system management mode (SMM) firmware, which operates at a higher privilege level than the operating system kernel. Exploitation of this vulnerability can result in arbitrary code execution within SMM, effectively allowing an attacker to execute code with the highest system privileges, bypassing OS-level security controls. The vulnerability is classified under CWE-787 (Out-of-bounds Write), indicating that the flaw involves writing data outside the intended memory boundaries. The CVSS v3.1 score of 8.2 reflects a high severity, with attack vector being local (AV:L), requiring low attack complexity (AC:L), high privileges (PR:H), no user interaction (UI:N), and a scope change (S:C) that affects confidentiality, integrity, and availability at a high level (C:H/I:H/A:H). No known exploits have been reported in the wild as of the publication date, but the potential impact is significant due to the ability to execute arbitrary code at the firmware level. The lack of specific vendor or product information limits precise identification of affected devices, but InsydeH2O is a widely used BIOS/UEFI firmware solution in many OEM devices, including laptops and embedded systems. This vulnerability highlights the critical risk posed by firmware-level flaws that can undermine system security from the lowest levels of the computing stack.

For European organizations, the impact of CVE-2022-35895 can be severe. Organizations relying on devices with InsydeH2O firmware versions containing this vulnerability face risks of firmware-level compromise, which can lead to persistent, stealthy attacks that are difficult to detect and remediate. Successful exploitation could allow attackers to bypass OS and hypervisor security, steal sensitive data, implant persistent malware, or disrupt system availability. This is particularly critical for sectors with high-value targets such as finance, government, critical infrastructure, and manufacturing, where firmware compromise could lead to espionage, sabotage, or data breaches. The local attack vector and requirement for high privileges mean that attackers would need some level of access to the target system, such as through compromised credentials or physical access, but once achieved, the attacker gains near-complete control. The scope change and high impact on confidentiality, integrity, and availability underscore the potential for widespread damage. European organizations with large fleets of laptops, embedded devices, or servers using InsydeH2O firmware should be especially vigilant. The absence of known exploits in the wild suggests a window of opportunity for proactive mitigation before widespread exploitation occurs.

Mitigation should focus on a multi-layered approach: 1) Firmware Updates: Organizations must identify devices using InsydeH2O firmware versions 5.0 through 5.5 and apply vendor-provided firmware patches or updates as soon as they become available. Coordination with device OEMs is critical to obtain and deploy these updates. 2) Access Controls: Since exploitation requires high privileges, enforcing strict access controls, including least privilege principles and robust authentication mechanisms, can reduce the risk of attackers gaining the necessary access. 3) Endpoint Security: Deploy advanced endpoint detection and response (EDR) solutions capable of monitoring for unusual SMI activity or firmware tampering attempts. 4) Physical Security: Prevent unauthorized physical access to devices, as local access could facilitate exploitation. 5) Firmware Integrity Verification: Implement runtime firmware integrity checks and secure boot mechanisms to detect unauthorized firmware modifications. 6) Network Segmentation: Limit lateral movement by segmenting networks and restricting access to critical systems that may be vulnerable. 7) Incident Response Preparedness: Develop and test incident response plans that include firmware compromise scenarios. 8) Vendor Engagement: Engage with Insyde and device OEMs to receive timely vulnerability disclosures and patches. Given the lack of patches at the time of disclosure, organizations should prioritize asset inventory and risk assessment to identify and isolate vulnerable systems until remediation is possible.