CVE-2021-45597 in CBR40
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by command injection by an authenticated user. This affects CBR40 before 2.5.0.24, CBR750 before 4.6.3.6, RBR850 before 3.2.17.12, RBS850 before 3.2.17.12, and RBS850 before 3.2.17.12.
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Analysis
by VulDB Data Team • 12/28/2021
This vulnerability represents a critical command injection flaw affecting multiple NETGEAR CBR and RBR series routers, specifically targeting firmware versions prior to the listed patches. The issue arises from insufficient input validation within the device's web management interface, allowing authenticated users to inject malicious commands that execute with elevated privileges. The vulnerability is particularly concerning because it requires only authentication credentials, which are often easily obtained through default configurations or weak password practices. The affected devices operate under the assumption that legitimate users can be trusted, creating a dangerous privilege escalation vector where authenticated access translates directly into arbitrary code execution capabilities. This aligns with CWE-77, which categorizes command injection vulnerabilities as critical due to their potential for system compromise and unauthorized access to network resources.
The technical implementation of this vulnerability stems from improper sanitization of user-supplied input within the device's web interface parameters. When authenticated users submit specific payloads through web forms or API endpoints, the system fails to properly validate or escape these inputs before processing them within system commands. This creates a direct path for attackers to inject operating system commands that bypass normal access controls and execute with the privileges of the web server process. The exploitation typically involves crafting malicious input that gets interpreted by the underlying shell, allowing attackers to execute arbitrary commands on the device. This pattern corresponds to ATT&CK technique T1059.001 for command and script injection, where adversaries leverage legitimate system tools to execute malicious code.
The operational impact of this vulnerability extends far beyond simple unauthorized access, as compromised routers can serve as persistent footholds for broader network attacks. An attacker with access to these devices can modify routing tables, redirect traffic, monitor network communications, and potentially establish backdoors for continued access. The affected CBR and RBR series devices often serve as primary network gateways, making them ideal targets for lateral movement within corporate networks. Once compromised, these devices can be used to launch attacks against internal systems, create botnet nodes, or provide attackers with persistent access to sensitive network segments. The vulnerability affects devices from multiple product lines, suggesting a systemic issue in the firmware development process that may impact other similar devices in the NETGEAR product catalog. Organizations using these devices face significant risk of data breaches, network disruption, and compliance violations, particularly in environments where network infrastructure security is paramount.
Mitigation strategies should focus on immediate firmware updates to patched versions, as these releases contain proper input validation and sanitization mechanisms. Network administrators must also implement strict access controls, including strong authentication mechanisms, regular credential rotation, and monitoring for unusual network traffic patterns. The vulnerability demonstrates the importance of principle of least privilege in network infrastructure, where administrative access should be limited and monitored. Additional defensive measures include network segmentation, intrusion detection system deployment, and regular vulnerability assessments of network infrastructure components. Organizations should also consider implementing device integrity monitoring to detect unauthorized changes to router configurations. The vulnerability serves as a reminder of the critical importance of firmware security in IoT and networking equipment, where unpatched devices can serve as primary attack vectors for sophisticated cyber campaigns. Regular security assessments and prompt patch management are essential to protect against similar vulnerabilities that may exist in other network infrastructure components.