CVE-2020-5376 in Inspiron 7347 BIOS
Summary
by MITRE
Dell Inspiron 7347 BIOS versions prior to A13 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
The vulnerability identified as CVE-2020-5376 affects Dell Inspiron 7347 laptops equipped with BIOS versions prior to A13, representing a critical security flaw within the UEFI firmware implementation. This issue stems from inadequate memory protection mechanisms during the boot process, specifically within the EFI_BOOT_SERVICES structure that governs system initialization and boot operations. The vulnerability creates a pathway for malicious actors to manipulate core boot services, potentially compromising the entire system integrity from the earliest stages of operation.
The technical exploitation of this vulnerability occurs through a sophisticated memory overwrite attack that targets the EFI_BOOT_SERVICES structure within the UEFI firmware environment. An attacker with local access to system memory can leverage this flaw to modify critical boot service tables, effectively rewriting the execution flow of the system's firmware initialization process. This manipulation allows for the execution of arbitrary code within the System Management Mode context, which operates with the highest privilege level and complete system access. The attack vector requires physical access to the target system, as the exploit necessitates direct memory manipulation capabilities that are typically restricted to authorized system components.
The operational impact of this vulnerability extends far beyond typical software exploits, as it compromises the fundamental security architecture of the device. System Management Mode represents a privileged execution environment where firmware components operate with unrestricted access to all system resources, including memory, I/O devices, and processor features. When an attacker can execute code within this mode, they gain the ability to persistently compromise the system, potentially installing rootkits, modifying system firmware, or establishing backdoors that survive complete system reboots. The vulnerability undermines the core principle of firmware security, as it allows attackers to bypass traditional operating system security controls and access mechanisms.
The security implications of this vulnerability align with CWE-119, which addresses "Improper Access to Memory" and specifically relates to weaknesses in memory management that enable attackers to manipulate critical system structures. From an ATT&CK framework perspective, this vulnerability maps to techniques involving firmware manipulation and privilege escalation, particularly targeting the system's boot process and firmware integrity. The attack leverages T1068, "Exploitation for Privilege Escalation," and T1542.001, "Pre-OS Boot," as it operates at the pre-operating system level and enables privilege escalation to the highest system privileges. Organizations should implement immediate mitigations including BIOS firmware updates to version A13 or later, along with comprehensive system monitoring to detect unauthorized firmware modifications. Additionally, physical security measures should be reinforced to prevent unauthorized access to system memory, and security teams should conduct thorough vulnerability assessments of all similar devices within their infrastructure to identify potential exposure to this class of attack.