CVE-2023-39539 is a vulnerability identified in the AMI AptioV BIOS firmware, specifically affecting version BKS_5.0. The root cause is improper input validation (CWE-20) combined with unrestricted file upload (CWE-434) of a PNG logo file via local access. This flaw allows a user with high privileges on the system to upload a maliciously crafted PNG file that the BIOS does not properly validate. Since the BIOS operates at a low level with high privileges, successful exploitation can compromise the confidentiality, integrity, and availability of the entire system. The vulnerability requires local access and high privileges, with no user interaction needed, and the scope is considered changed because the impact extends beyond the local user to the entire system firmware. The CVSS v3.1 score is 7.5 (High), reflecting the significant impact but higher attack complexity and privilege requirements. No public exploits or patches are currently available, increasing the risk window. The vulnerability could be leveraged to implant persistent malware or disrupt system boot processes, severely impacting system security and availability.

For European organizations, the impact of CVE-2023-39539 is substantial. Compromise of BIOS firmware can lead to persistent, stealthy malware infections that survive OS reinstalls and can evade traditional security controls. This threatens confidentiality by potentially exposing sensitive data, integrity by allowing unauthorized firmware modifications, and availability by disrupting system boot or operation. Critical sectors such as finance, government, healthcare, and critical infrastructure are particularly vulnerable due to the high value of their data and systems. The requirement for local high-privilege access limits remote exploitation but insider threats or compromised administrative accounts could facilitate attacks. The lack of patches increases exposure time, and organizations relying on AMI AptioV BIOS in their hardware supply chain must prioritize mitigation to avoid long-term compromise.

1. Restrict and monitor local administrative access to systems with AMI AptioV BIOS to prevent unauthorized users from uploading files. 2. Implement strict access controls and auditing on BIOS update and configuration utilities to detect and prevent unauthorized modifications. 3. Employ endpoint detection and response (EDR) solutions capable of monitoring firmware-level changes or suspicious activities related to BIOS. 4. Coordinate with hardware vendors and AMI to obtain and apply firmware updates or patches as soon as they become available. 5. Conduct regular security training for administrators to recognize and prevent misuse of local privileges. 6. Use hardware-based security features such as TPM and Secure Boot to detect unauthorized firmware changes. 7. Maintain an inventory of affected hardware to prioritize remediation efforts. 8. Consider network segmentation to limit access to critical systems and reduce insider threat risks.