CVE-2022-3744 in LCFC BIOS
Summary
by MITRE • 08/23/2023
A potential vulnerability was discovered in LCFC BIOS for some Lenovo consumer notebook models that could allow a local attacker with elevated privileges to unlock UEFI variables due to a hard-coded SMI handler credential.
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Analysis
by VulDB Data Team • 08/24/2023
The vulnerability identified as CVE-2022-3744 resides within the LCFC BIOS implementation used in certain Lenovo consumer notebook models, representing a critical security flaw that undermines the fundamental integrity of the Unified Extensible Firmware Interface. This weakness stems from a hard-coded SMI (System Management Interrupt) handler credential that persists across multiple device generations, creating a persistent backdoor mechanism that can be exploited by attackers with local elevated privileges. The flaw fundamentally compromises the UEFI secure boot process and firmware protection mechanisms that are designed to prevent unauthorized modification of critical system components.
The technical implementation of this vulnerability manifests through the improper handling of SMI interrupts within the firmware layer, where a hardcoded credential allows unauthorized access to UEFI variable protection mechanisms. This design flaw falls under the CWE-798 category of using hardcoded credentials, which directly violates security best practices and creates a permanent access vector for attackers who can elevate their privileges locally. The SMI handler operates at the highest privilege level within the firmware, making this vulnerability particularly dangerous as it provides direct access to firmware configuration and variable manipulation capabilities. The hard-coded nature of the credential means that regardless of system updates or security patches applied at the operating system level, the underlying firmware vulnerability remains persistent.
From an operational perspective, this vulnerability creates significant risk for Lenovo consumer notebook users as it enables a local attacker with elevated privileges to bypass UEFI variable protection mechanisms entirely. The impact extends beyond simple privilege escalation, as compromised UEFI variables can lead to complete system compromise through firmware rootkit installation, secure boot bypass, and persistent backdoor creation. Attackers can manipulate critical system parameters including boot order, firmware settings, and secure boot policies, effectively undermining the entire security architecture of the device. This vulnerability is particularly concerning because UEFI variables are typically protected by the firmware itself, and the hard-coded credential undermines these protections entirely. The attack surface is limited to local access with elevated privileges but the potential impact is severe, as it allows for persistent system compromise that can survive operating system reinstallation and hardware replacement.
Mitigation strategies for CVE-2022-3744 require immediate firmware updates from Lenovo to address the hardcoded credential issue, though the nature of firmware vulnerabilities means that complete remediation may require hardware-level changes to the SMI handler implementation. Organizations should implement strict access controls and privilege management to minimize local elevated privilege exposure, while security monitoring should focus on detecting unauthorized changes to UEFI variables and boot configurations. The vulnerability demonstrates the critical importance of firmware security in modern computing environments, as the attack surface extends beyond traditional operating system boundaries into the fundamental firmware layer. Security professionals should also consider implementing firmware integrity monitoring solutions and regularly audit UEFI variable configurations to detect potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1542.003 for exploitation of firmware, emphasizing the need for comprehensive firmware security practices that extend beyond traditional software security measures.