CVE-2021-45617 in CBR40
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by command injection by an unauthenticated attacker. This affects CBR40 before 2.5.0.24, EAX20 before 1.0.0.48, EAX80 before 1.0.1.64, EX7500 before 1.0.0.72, R6400 before 1.0.1.68, R6900P before 1.3.2.132, R7000 before 1.0.11.116, R7000P before 1.3.2.132, R7900 before 1.0.4.38, R7960P before 1.4.1.66, R8000 before 1.0.4.66, RAX200 before 1.0.3.106, RS400 before 1.5.1.80, XR300 before 1.0.3.68, MK62 before 1.0.6.110, MR60 before 1.0.6.110, R6400v2 before 1.0.4.106, R8000P before 1.4.1.66, RAX20 before 1.0.2.64, RAX45 before 1.0.2.82, RAX80 before 1.0.3.106, MS60 before 1.0.6.110, R6700v3 before 1.0.4.106, R7900P before 1.4.1.66, RAX15 before 1.0.2.64, RAX50 before 1.0.2.82, RAX75 before 1.0.3.106, RBR750 before 3.2.16.22, RBR850 before 3.2.16.22, RBS750 before 3.2.16.22, RBS850 before 3.2.16.22, RBK752 before 3.2.16.22, and RBK852 before 3.2.16.22.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 12/28/2021
This vulnerability represents a critical command injection flaw in multiple NETGEAR router models that allows unauthenticated attackers to execute arbitrary commands on affected devices. The vulnerability stems from insufficient input validation and sanitization in the web interface handling of specific parameters, enabling remote attackers to inject malicious commands that are then executed with the privileges of the web server process. The affected device families span across various router series including CBR40, R6400, R7900, R8000, RAX200, and numerous others, indicating a widespread issue affecting both consumer and business grade networking equipment. The vulnerability exists in firmware versions prior to the specified patches, with each model having its own version threshold for protection. This flaw directly violates security principles outlined in CWE-77, which specifically addresses command injection vulnerabilities where user-supplied data is improperly incorporated into system commands without adequate sanitization or validation. The attack vector is particularly concerning as it requires no authentication, making it accessible to anyone who can reach the device's web interface over the network. The impact of this vulnerability extends beyond simple command execution, as it can enable attackers to gain full control of the affected devices, potentially leading to network compromise, data exfiltration, or use as a pivot point for attacking other systems within the local network.
The technical implementation of this vulnerability occurs through improper handling of HTTP parameters in the device's web server component, where user input is directly passed to system commands without proper sanitization. Attackers can craft malicious requests that include shell metacharacters such as semicolons, pipes, or command separators that get interpreted by the underlying operating system. This allows for arbitrary code execution with elevated privileges, potentially enabling attackers to modify device configurations, install malware, or redirect network traffic. The vulnerability affects devices running firmware versions that predate the specified security patches, with some models requiring updates to versions as recent as 1.4.1.66 or 2.5.0.24. The exploitation requires network access to the device's management interface, typically accessible via HTTP or HTTPS ports, and can be performed remotely without any authentication credentials. This aligns with ATT&CK technique T1059.001 for command and scripting interpreter, specifically shell scripting, which is a core component of many attack frameworks targeting network infrastructure. The widespread nature of affected models suggests this was likely a design flaw in the web application framework rather than an isolated incident, potentially affecting hundreds of thousands of devices globally. The vulnerability can be exploited to establish persistent access to networks through compromised devices, making it particularly dangerous in enterprise environments where these routers serve as network gateways.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete control over affected devices and potentially the entire local network they protect. Successful exploitation can result in man-in-the-middle attacks, DNS hijacking, traffic interception, and unauthorized access to sensitive network resources. The compromised devices can be used as command and control nodes for further attacks, or attackers can use them to establish backdoors for future access. Organizations relying on these devices for network security may find their defenses compromised, as the routers themselves become attack vectors rather than protective barriers. The vulnerability also impacts network availability, as attackers can potentially cause device crashes or reboots through malicious command injection. The scope of affected devices includes both residential and business-grade routers, with many enterprise deployments likely affected given the widespread use of NETGEAR equipment in small to medium business environments. The patching process for these devices requires careful coordination as many are deployed in remote locations or managed by third parties, potentially creating extended periods of vulnerability exposure. This vulnerability directly impacts the CIA triad by compromising confidentiality through data interception, integrity through configuration modification, and availability through potential denial of service conditions. Network administrators should consider this vulnerability as a high-priority threat requiring immediate attention and remediation across all affected device models.
Mitigation strategies should focus on immediate firmware updates for all affected device models, as these patches address the root cause of the command injection vulnerability. Organizations should conduct comprehensive inventory audits to identify all affected devices within their network infrastructure, particularly those with exposed management interfaces. Network segmentation and access controls should be implemented to limit access to device management interfaces to authorized personnel only, reducing the attack surface for unauthenticated exploitation attempts. Regular network monitoring should be deployed to detect anomalous traffic patterns that might indicate exploitation attempts, including unusual command execution patterns or unexpected device behavior. Device hardening procedures should be implemented, including disabling unnecessary services, changing default credentials, and configuring firewall rules to restrict access to management interfaces. Security teams should also consider implementing intrusion detection systems that can identify known attack patterns associated with command injection exploits. The vulnerability highlights the importance of secure coding practices and input validation in network device firmware development, as outlined in industry standards such as OWASP Top 10 and NIST cybersecurity guidelines. Organizations should also consider implementing network access control measures and regular security assessments to identify similar vulnerabilities in other network infrastructure components. Given the nature of the vulnerability and its potential for remote exploitation without authentication, immediate action is required to prevent unauthorized access and maintain network security posture. The vulnerability serves as a reminder of the critical importance of firmware security and the need for continuous monitoring and updating of network infrastructure components to prevent exploitation by threat actors.