CVE-2021-45536 in RAX75
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by command injection by an authenticated user. This affects RAX75 before 1.0.3.106, RAX80 before 1.0.3.106, RBK752 before 3.2.16.6, RBR750 before 3.2.16.6, RBS750 before 3.2.16.6, RBK852 before 3.2.16.6, RBR850 before 3.2.16.6, and RBS850 before 3.2.16.6.
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Analysis
by VulDB Data Team • 12/28/2021
The vulnerability CVE-2021-45536 represents a critical command injection flaw affecting multiple NETGEAR router models within the RAX and RBK/RBR/RBS series. This vulnerability exists in firmware versions prior to specific patches, creating a significant security risk for affected devices. The flaw allows authenticated users to execute arbitrary commands on the affected devices, potentially enabling attackers with legitimate network access to gain full control over the router's functionality. The affected models include RAX75, RAX80, and various RBK, RBR, and RBS series routers, all of which are vulnerable due to insufficient input validation in their web-based management interfaces.
The technical implementation of this vulnerability stems from improper sanitization of user-supplied input within the device's web administration portal. When authenticated users submit commands through specific parameters in the web interface, the system fails to properly validate or escape these inputs before processing them. This creates an environment where maliciously crafted input can be interpreted as shell commands rather than simple data, allowing attackers to execute arbitrary code with the privileges of the web server process. The vulnerability aligns with CWE-77 and CWE-89, which specifically address command injection and SQL injection flaws respectively, and represents a clear violation of secure input handling principles. The flaw operates at the application layer, making it particularly dangerous as it requires minimal privileges to exploit once an attacker has gained authentication access to the device.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it can enable attackers to completely compromise the affected routers. Successful exploitation could allow threat actors to modify network configurations, redirect traffic through malicious proxies, establish backdoors, or use the compromised devices as entry points for further network infiltration. The vulnerability is particularly concerning in enterprise environments where these devices may serve as network gateways, as it could facilitate lateral movement and persistent access to internal networks. From an attack framework perspective, this vulnerability maps to ATT&CK technique T1059.001 for command and scripting interpreter and T1021.001 for remote services, representing both execution and lateral movement capabilities. The authenticated nature of the exploit means that even devices with strong network segmentation could be compromised if an attacker gains legitimate user credentials or if the device uses weak default credentials.
Mitigation strategies for CVE-2021-45536 must prioritize immediate firmware updates from NETGEAR to address the root cause of the command injection vulnerability. Organizations should also implement network monitoring to detect suspicious command execution patterns and establish strict access controls for router management interfaces. Regular security audits of network infrastructure should include verification of firmware versions and patch status for all affected devices. Network segmentation and firewall rules should be implemented to restrict access to administrative interfaces to only authorized personnel. Additionally, implementing multi-factor authentication for router management access and disabling unnecessary administrative services can significantly reduce the attack surface. Security teams should also consider deploying intrusion detection systems capable of identifying command injection attempts and establishing incident response procedures specifically addressing router compromise scenarios. The vulnerability underscores the importance of maintaining up-to-date firmware and implementing robust network access controls as fundamental defensive measures against authenticated command injection attacks.