CVE-2023-43571 in Desktop BIOS
Summary
by MITRE • 11/09/2023
A buffer overflow was reported in the BiosExtensionLoader module in some Lenovo Desktop products that may allow a local attacker with elevated privileges to execute arbitrary code.
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Analysis
by VulDB Data Team • 11/09/2023
The vulnerability identified as CVE-2023-43571 represents a critical buffer overflow flaw within the BiosExtensionLoader module of specific Lenovo desktop computing systems. This issue resides in the firmware layer of the system architecture, specifically affecting the boot process and system initialization procedures where the BIOS extension loader component operates. The vulnerability manifests when the system attempts to process certain input data within the BIOS extension loading mechanism, creating a condition where memory boundaries are exceeded during data handling operations.
The technical exploitation of this buffer overflow vulnerability occurs within the BiosExtensionLoader module which is responsible for loading and executing BIOS extensions during system boot sequences. When malformed or oversized input data is processed by this module, the lack of proper bounds checking allows memory corruption to occur, potentially leading to arbitrary code execution. This flaw specifically impacts systems where the BIOS extension loader does not properly validate the size and content of data structures before copying them into fixed-size memory buffers. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, where insufficient bounds checking enables attackers to overwrite adjacent memory locations.
The operational impact of this vulnerability is significant for affected Lenovo desktop systems, as it provides a local attacker with elevated privileges the capability to execute malicious code within the system firmware context. This represents a particularly dangerous condition since the BIOS extension loader operates at the lowest privilege level during system boot, making it an attractive target for attackers seeking to establish persistent footholds within the computing environment. The attack vector requires local access with elevated privileges, typically corresponding to administrator or root-level access, but the potential for privilege escalation remains high due to the firmware-level nature of the vulnerability. The exploitation could enable attackers to modify system firmware, install rootkits, or establish backdoors that persist beyond traditional operating system boundaries.
Mitigation strategies for CVE-2023-43571 should prioritize immediate firmware updates from Lenovo, as these patches typically address the buffer overflow conditions through proper bounds checking and memory validation mechanisms. Organizations should implement comprehensive inventory management to identify all affected Lenovo desktop models and ensure timely patch deployment across their computing environments. The vulnerability aligns with ATT&CK technique T1068 which involves exploiting vulnerabilities in legitimate system processes, and T1542 which covers privilege escalation through exploitation of system components. Additional protective measures include implementing firmware integrity monitoring, restricting local administrative access, and establishing robust system hardening procedures that limit the attack surface for firmware-level exploits. Security teams should also consider implementing runtime protection mechanisms that can detect anomalous behavior in BIOS extension loading processes and monitor for potential exploitation attempts.