CVE-2021-40045 in EMUI
Summary
by MITRE • 02/10/2022
There is a vulnerability of signature verification mechanism failure in system upgrade through recovery mode.Successful exploitation of this vulnerability may affect service confidentiality.
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Analysis
by VulDB Data Team • 02/14/2022
The vulnerability identified as CVE-2021-40045 represents a critical flaw in the signature verification mechanism that governs system upgrades executed through recovery mode. This weakness fundamentally undermines the integrity and authenticity checks that are essential for maintaining secure system operations. The vulnerability exists within the firmware or software components responsible for validating upgrade packages during recovery processes, creating a pathway for malicious actors to bypass legitimate authentication procedures. Such a failure in signature verification constitutes a direct violation of security principles that ensure only authorized and verified software can be installed on target systems, potentially allowing unauthorized modifications to critical system components.
The technical implementation of this vulnerability stems from inadequate validation of digital signatures or cryptographic checks during the recovery upgrade process. Attackers can exploit this weakness by crafting malicious upgrade packages that appear to be legitimate system updates but contain unauthorized code or modifications. The flaw typically manifests when the system fails to properly verify the cryptographic signatures of upgrade files, allowing forged packages to be accepted and installed without proper authentication. This mechanism failure operates at a low level within the system's boot and recovery processes, making it particularly dangerous as it can be triggered before normal security controls are fully operational. The vulnerability's impact extends beyond simple unauthorized access, as it can potentially enable privilege escalation, persistent backdoor installation, or complete system compromise depending on the recovery mode's privileges.
The operational implications of CVE-2021-40045 are severe and multifaceted, particularly affecting service confidentiality and overall system integrity. When exploited successfully, this vulnerability can result in unauthorized modification of critical system components, potentially leading to data exfiltration, system takeover, or persistent access for attackers. The recovery mode context amplifies the risk significantly since these modes are often designed for troubleshooting or emergency repairs and may operate with elevated privileges or reduced security controls. Organizations relying on affected systems face potential exposure to supply chain attacks where malicious actors compromise upgrade processes to gain access to target environments. The vulnerability's presence in recovery mechanisms also means that traditional security monitoring and endpoint protection may not detect the compromise, as the attack occurs at a level below normal operational security controls.
Mitigation strategies for CVE-2021-40045 should focus on strengthening the signature verification mechanisms and implementing additional security controls within recovery processes. System administrators should ensure that all firmware and software components are updated with patches that address the specific signature verification flaw, while also implementing strict access controls for recovery mode operations. The implementation of hardware-based security features such as secure boot mechanisms and trusted platform modules can provide additional layers of protection against unauthorized modifications. Organizations should also establish robust monitoring procedures specifically designed to detect anomalies in recovery mode operations and upgrade processes, as these areas may be less visible to standard security systems. According to CWE classification, this vulnerability aligns with CWE-311, which addresses the absence of encryption or weak encryption of sensitive data, and may also relate to CWE-310 for cryptographic failures. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence through system modification, specifically targeting the system boot and recovery processes to establish long-term access to affected systems.