CVE-2021-33205 in EdgeRover
Summary
by MITRE • 06/11/2021
Western Digital EdgeRover before 0.25 has an escalation of privileges vulnerability where a low privileged user could load malicious content into directories with higher privileges, because of how Node.js is used. An attacker can gain admin privileges and carry out malicious activities such as creating a fake library and stealing user credentials.
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Analysis
by VulDB Data Team • 06/14/2021
The CVE-2021-33205 vulnerability affects Western Digital EdgeRover devices running firmware versions prior to 0.25, representing a critical privilege escalation flaw that fundamentally compromises the device's security architecture. This vulnerability stems from improper privilege management within the Node.js runtime environment, creating a dangerous attack vector that allows low-privileged users to manipulate system directories with elevated permissions. The flaw specifically manifests when the system fails to properly validate or restrict file loading operations, enabling malicious actors to inject content into directories that should normally be restricted to administrative access. The vulnerability is particularly concerning because it operates at the core of the device's application execution environment, where Node.js serves as the primary runtime for handling various system functions and user interactions.
The technical implementation of this vulnerability involves a classic path traversal and privilege escalation pattern where the Node.js framework does not adequately enforce access controls when processing file operations. Attackers can exploit this by leveraging the existing user account permissions to load malicious code or content into system directories that typically require administrative privileges to modify. The Node.js runtime environment's handling of file system operations appears to lack proper sandboxing or privilege separation mechanisms, allowing the low-privileged user context to perform operations that should be restricted to higher-privileged processes. This flaw creates a persistent backdoor within the system architecture, enabling attackers to establish malicious persistence while maintaining elevated privileges throughout their operations.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it provides attackers with comprehensive administrative control over the EdgeRover device. Once successfully exploited, attackers can create fake library components that appear legitimate to the system's validation processes, effectively bypassing security checks designed to prevent unauthorized modifications. The stolen user credentials obtained through this attack vector can be used for lateral movement within network environments, potentially compromising additional systems that rely on the same authentication mechanisms. This vulnerability also enables attackers to establish persistent access points, modify system configurations, and potentially exfiltrate sensitive data from connected network infrastructure. The implications are particularly severe for edge computing environments where these devices often serve as critical network nodes with access to sensitive corporate or consumer data.
Mitigation strategies for CVE-2021-33205 should prioritize immediate firmware updates to version 0.25 or later, which contain the necessary patches to address the privilege escalation mechanism. Organizations should implement network segmentation to limit access to EdgeRover devices and reduce the attack surface available to potential adversaries. Additional security measures include implementing strict file system access controls, monitoring for unauthorized file modifications, and conducting regular security audits of Node.js applications running on affected systems. The vulnerability aligns with CWE-269: "Improper Privilege Management" and represents a clear violation of the principle of least privilege, as defined in the MITRE ATT&CK framework under the Privilege Escalation technique. System administrators should also consider implementing application whitelisting policies and restricting Node.js execution privileges to prevent similar vulnerabilities from being exploited in other components of the device's architecture.