CVE-2021-45634 in CBR750
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by command injection by an unauthenticated attacker. This affects CBR750 before 4.6.3.6, RBK752 before 3.2.17.12, RBR750 before 3.2.17.12, RBS750 before 3.2.17.12, RBK852 before 3.2.17.12, RBR850 before 3.2.17.12, and RBS850 before 3.2.17.12.
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Analysis
by VulDB Data Team • 12/28/2021
The vulnerability identified as CVE-2021-45634 represents a critical command injection flaw affecting multiple NETGEAR router models within the CBR750, RBK752, RBR750, RBS750, RBK852, RBR850, and RBS850 device families. This security weakness allows unauthenticated attackers to execute arbitrary commands on affected devices, potentially compromising the entire network infrastructure. The vulnerability stems from insufficient input validation and sanitization within the device's web interface, specifically in the handling of user-supplied parameters that are directly passed to system commands without proper filtering mechanisms.
The technical implementation of this command injection vulnerability occurs through the manipulation of web interface parameters that are processed by the device's underlying operating system. Attackers can exploit this flaw by crafting malicious HTTP requests containing specially formatted command sequences that bypass authentication requirements and execute arbitrary code with the privileges of the web server process. This type of vulnerability maps directly to CWE-77, which specifically addresses command injection flaws in software applications, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter. The affected firmware versions indicate that this vulnerability has persisted across multiple device generations, suggesting a systemic flaw in the development and testing processes rather than an isolated incident.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as successful exploitation can result in complete network compromise, data exfiltration, and potential lateral movement within the affected network. An unauthenticated attacker can gain root-level access to the device, enabling them to modify network configurations, install malware, monitor network traffic, or establish persistent backdoors. The vulnerability affects devices that are commonly deployed in residential and small office environments, where network security is often insufficiently implemented, making these targets particularly attractive for malicious actors. The lack of authentication requirements for exploitation means that attackers can target these devices from outside the network perimeter, significantly expanding the attack surface and reducing the effectiveness of traditional network security controls.
Mitigation strategies for CVE-2021-45634 should prioritize immediate firmware updates to versions 4.6.3.6 and 3.2.17.12 or later for the affected device models, as provided by NETGEAR. Network administrators should also implement network segmentation and access control measures to limit the potential impact of successful exploitation. Additional protective measures include disabling unnecessary services, implementing robust firewall rules, and conducting regular security assessments of network infrastructure. The vulnerability highlights the importance of secure coding practices and proper input validation, particularly for web applications that interface with system commands. Organizations should also consider implementing network monitoring solutions to detect anomalous traffic patterns that may indicate exploitation attempts. Given the nature of command injection vulnerabilities, the implementation of web application firewalls and input sanitization mechanisms can provide additional layers of protection against similar attack vectors. The affected devices represent a significant risk to network security, particularly in environments where network access controls are minimal or non-existent, emphasizing the critical need for prompt remediation and ongoing security monitoring.