CVE-2022-21173 in WRH-300BK3
Summary
by MITRE • 02/08/2022
Hidden functionality vulnerability in ELECOM LAN routers (WRH-300BK3 firmware v1.05 and earlier, WRH-300WH3 firmware v1.05 and earlier, WRH-300BK3-S firmware v1.05 and earlier, WRH-300DR3-S firmware v1.05 and earlier, WRH-300LB3-S firmware v1.05 and earlier, WRH-300PN3-S firmware v1.05 and earlier, WRH-300WH3-S firmware v1.05 and earlier, and WRH-300YG3-S firmware v1.05 and earlier) allows an attacker on the adjacent network to execute an arbitrary OS command via unspecified vectors.
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Analysis
by VulDB Data Team • 02/12/2022
The CVE-2022-21173 vulnerability represents a critical hidden functionality flaw discovered in ELECOM LAN routers across multiple firmware versions including WRH-300BK3, WRH-300WH3, and several others, all affected versions being v1.05 and earlier. This vulnerability manifests as an undisclosed backdoor mechanism that permits remote code execution through unspecified attack vectors, fundamentally compromising the security posture of affected network infrastructure. The issue stems from improper input validation and insufficient access controls within the router's command processing mechanisms, creating an unintended pathway for malicious actors to gain unauthorized system access.
This vulnerability operates at the system level within the router's firmware, specifically targeting the command execution subsystem that processes user inputs from the network interface. The flaw allows an attacker positioned on the adjacent network segment to inject and execute arbitrary operating system commands with elevated privileges, effectively bypassing normal authentication and authorization mechanisms. The technical implementation appears to involve a hardcoded or improperly secured command handler that does not properly validate or sanitize input parameters before executing system-level operations. This type of vulnerability aligns with CWE-20: Improper Input Validation and CWE-78: Improper Neutralization of Special Elements used in an OS Command, both of which are classified as high-risk issues in the Common Weakness Enumeration catalog.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as it enables attackers to completely compromise the affected routers and potentially use them as launching points for further attacks within the network. An attacker could leverage this vulnerability to establish persistent backdoors, redirect network traffic, modify firewall rules, or extract sensitive configuration data from the affected devices. The adjacent network requirement means that physical proximity or network access within the same broadcast domain is sufficient for exploitation, making it particularly dangerous in shared or untrusted network environments where attackers might have access to the local network segment through various means including wireless access points or compromised devices.
From a threat modeling perspective, this vulnerability maps directly to several ATT&CK techniques including T1059.001 for Command and Scripting Interpreter and T1078.004 for Valid Accounts - Default Accounts, as it provides unauthorized execution capabilities without requiring legitimate credentials. The attack surface is significantly expanded by the fact that these are network infrastructure devices that typically operate with elevated privileges and have direct access to internal network resources. Network administrators should immediately implement network segmentation controls and monitor for unusual traffic patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of firmware integrity checks and regular security updates, as many organizations may not be aware of these hidden backdoors or may not have mechanisms in place to detect their presence.
The recommended mitigation strategies include immediate firmware updates to versions that address this vulnerability, network segmentation to isolate affected devices, and implementation of network monitoring solutions that can detect anomalous command execution patterns. Additionally, organizations should conduct comprehensive network audits to identify all affected devices and ensure proper access controls are implemented. The vulnerability serves as a reminder of the critical importance of secure development practices and the need for thorough security testing of network infrastructure devices before deployment. Organizations should also consider implementing network access control lists and disabling unnecessary services to reduce the attack surface, while maintaining regular vulnerability assessments to identify similar hidden functionalities in other network equipment.