CVE-2021-45560 in RBK752
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by command injection by an authenticated user. This affects 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-2021-45560 represents a critical command injection flaw affecting multiple NETGEAR router models including RBK752, RBR750, RBS750, RBK852, RBR850, and RBS850. This issue stems from insufficient input validation within the web management interface of these devices, allowing authenticated users to execute arbitrary commands on the underlying operating system. The vulnerability specifically impacts firmware versions prior to 3.2.16.6, indicating a widespread concern across several router generations that were likely deployed in both residential and small business environments. The affected devices operate on embedded systems that process user-supplied input without proper sanitization, creating a pathway for malicious command execution that could compromise the entire network infrastructure.
The technical implementation of this vulnerability resides in the web server component of the router firmware where user inputs are directly passed to system commands without adequate filtering or escaping mechanisms. When an authenticated user submits malicious input through the web interface, the system processes these commands through shell execution functions, enabling attackers to inject arbitrary shell commands that execute with the privileges of the web server process. This flaw aligns with CWE-77 and CWE-88 categories, representing command injection vulnerabilities that occur when untrusted data is incorporated into system commands without proper validation or sanitization. The authenticated nature of the attack means that an adversary must first obtain valid credentials to the device's web management interface, but once achieved, the impact is severe as the attacker gains the ability to execute commands with elevated privileges.
The operational impact of this vulnerability extends beyond simple command execution, as it provides attackers with comprehensive control over the affected routers. An attacker could potentially modify firewall rules, redirect network traffic, extract sensitive configuration data, install malware, or even create backdoors for persistent access. The implications for network security are significant since routers serve as critical gateways in network infrastructure, and compromising them can lead to widespread network disruption, data exfiltration, or serving as a launching point for attacks on connected devices. This vulnerability particularly affects environments where these routers are deployed without proper network segmentation or monitoring, as the compromised device could be used to pivot attacks to other systems within the network. The attack surface is further expanded by the fact that these devices are commonly accessible from both internal and external networks, especially when default credentials are not changed.
Mitigation strategies for CVE-2021-45560 primarily focus on firmware updates and access control measures. NETGEAR released firmware version 3.2.16.6 and later to address this vulnerability, making immediate patching the most effective remediation approach for affected devices. Organizations should also implement strict access controls for router management interfaces, including changing default credentials, implementing strong authentication mechanisms, and restricting access to management interfaces to authorized personnel only. Network segmentation and monitoring solutions can help detect anomalous behavior that might indicate exploitation attempts, while regular vulnerability assessments should be conducted to identify and remediate similar issues in other network infrastructure components. The ATT&CK framework categorizes this vulnerability under T1059.001 for command and script injection, and T1068 for exploit for privilege escalation, highlighting the need for comprehensive defensive measures that address both initial access and post-compromise activities. Additionally, implementing network access control lists and disabling unnecessary services can reduce the attack surface and limit the potential impact of such vulnerabilities in the broader network environment.