CVE-2021-38520 in R6400
Summary
by MITRE • 08/11/2021
Certain NETGEAR devices are affected by command injection by an authenticated user. This affects R6400 before 1.0.1.52, R6400v2 before 1.0.4.84, R6700v3 before 1.0.4.84, R6700v2 before 1.2.0.62, R6900v2 before 1.2.0.62, and R7000P before 1.3.2.124.
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Analysis
by VulDB Data Team • 08/16/2021
The vulnerability CVE-2021-38520 represents a critical command injection flaw affecting multiple NETGEAR router models including R6400, R6400v2, R6700v3, R6700v2, R6900v2, and R7000P. This security weakness allows authenticated attackers to execute arbitrary commands on affected devices by leveraging improper input validation mechanisms within the device's web interface. The flaw exists in the handling of user-supplied parameters that are directly passed to system commands without adequate sanitization or escaping, creating a pathway for malicious command execution. The vulnerability specifically impacts firmware versions prior to the mentioned patches, indicating that NETGEAR released targeted fixes to address this issue in their device management systems.
From a technical perspective, the vulnerability stems from insufficient validation of input parameters submitted through the web administration interface. When authenticated users submit specific parameters to the router's management web server, the system fails to properly sanitize or escape these inputs before incorporating them into system command executions. This pattern aligns with CWE-77, which describes improper neutralization of special elements used in command execution contexts. The flaw essentially allows attackers to inject malicious commands that get executed with the privileges of the web server process, typically running with administrative or root-level access on the device. The authentication requirement means that an attacker must first establish a valid session with the device, typically through legitimate administrative credentials, before being able to exploit this vulnerability.
The operational impact of this vulnerability extends beyond simple unauthorized access to potentially full device compromise and network infiltration. An authenticated attacker could leverage this command injection to gain complete control over the affected router, enabling them to modify network configurations, redirect traffic, establish backdoors, or use the device as a pivot point for attacking other systems within the local network. This vulnerability particularly concerns network administrators because routers serve as critical infrastructure components that control network traffic flow and often provide the first line of defense against external threats. The fact that multiple generations of NETGEAR routers are affected suggests a systemic issue in how these devices handle user input, potentially indicating broader architectural weaknesses in the firmware's security implementation. The vulnerability could also enable attackers to exfiltrate sensitive network information or disrupt network services, making it a significant concern for both residential and enterprise users.
Mitigation strategies for CVE-2021-38520 should focus on immediate firmware updates from NETGEAR, as the vendor has released patches specifically addressing this vulnerability. Organizations should prioritize updating all affected router models to their latest firmware versions, particularly those running versions prior to the specified secure releases. Network segmentation and access controls should be implemented to limit administrative access to these devices, reducing the attack surface available to potential attackers. Regular security audits should include verification that devices are running patched firmware versions and that no unauthorized administrative access has occurred. Additionally, implementing network monitoring solutions that can detect unusual traffic patterns or command execution attempts may help identify exploitation attempts. The vulnerability highlights the importance of secure coding practices in embedded systems and reinforces the need for regular security assessments of network infrastructure devices. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command execution and privilege escalation, making it a significant concern for defensive security teams responsible for protecting network infrastructure.