CVE-2020-5378 in G7 17 7790
Summary
by MITRE
Dell G7 17 7790 BIOS versions prior to 1.13.2 contain a UEFI BIOS Boot Services overwrite vulnerability. A local attacker with access to system memory may exploit this vulnerability by overwriting the EFI_BOOT_SERVICES structure to execute arbitrary code in System Management Mode (SMM).
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Analysis
by VulDB Data Team • 11/12/2020
This vulnerability resides within the UEFI BIOS implementation of Dell G7 17 7790 laptops running firmware versions earlier than 1.13.2. The flaw represents a critical security weakness that allows local attackers with system memory access to manipulate the EFI_BOOT_SERVICES structure, effectively compromising the system's foundational boot process. The vulnerability stems from inadequate memory protection mechanisms during the UEFI boot phase, creating an exploitable condition where malicious code can overwrite critical boot services data structures.
The technical exploitation involves overwriting the EFI_BOOT_SERVICES structure which serves as a critical interface between the UEFI firmware and the operating system during the boot process. When an attacker successfully overwrites this structure, they gain the ability to execute arbitrary code within the System Management Mode context, which operates with the highest privilege level in the system architecture. This privilege escalation allows the attacker to bypass standard operating system security controls and potentially gain complete system control. The vulnerability specifically targets the UEFI boot services that are responsible for initializing the system environment and managing boot processes, making it particularly dangerous as it can be exploited before the operating system loads.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to establish persistent backdoors within the system's firmware layer. Since the exploitation occurs during the UEFI boot phase, any malicious code executed in SMM can survive operating system reboots and remain undetected by traditional security mechanisms. This makes the vulnerability particularly dangerous for enterprise environments where persistent threats are a primary concern, and for users who store sensitive data on these devices. The local attack requirement means that physical access or remote code execution capabilities must first be established, but once achieved, the attack can be devastating.
The vulnerability maps directly to CWE-248, which addresses "Uncaught Exception in UEFI" and represents a failure in proper exception handling within the UEFI environment. It also aligns with ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation" and specifically targets firmware-based attacks that leverage system management mode access. Organizations should implement immediate mitigation measures including firmware updates to version 1.13.2 or later, which address the memory protection gaps in the EFI_BOOT_SERVICES structure. Additionally, system administrators should consider implementing hardware security modules and firmware integrity monitoring solutions to detect unauthorized modifications to the UEFI firmware. Regular security assessments should include verification of UEFI firmware integrity and monitoring for signs of persistent threats that may exploit similar firmware vulnerabilities. The remediation process must include comprehensive testing of firmware updates to ensure compatibility with existing system configurations and avoid potential boot failures that could compromise system availability.