CVE-2018-21116 in XR500
Summary
by MITRE
NETGEAR XR500 devices before 2.3.2.32 are affected by remote code execution by unauthenticated attackers.
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Analysis
by VulDB Data Team • 06/01/2024
The vulnerability identified as CVE-2018-21116 affects NETGEAR XR500 wireless routers and is classified as a remote code execution flaw that can be exploited by unauthenticated attackers. This critical security weakness resides within the device's web interface and allows malicious actors to execute arbitrary code on the affected hardware without requiring any authentication credentials. The vulnerability specifically impacts firmware versions prior to 2.3.2.32, making all earlier releases susceptible to exploitation. The affected device model represents part of NETGEAR's XR series, which are typically deployed in residential and small office environments where they serve as primary network gateways and provide essential connectivity services.
The technical root cause of this vulnerability stems from improper input validation and sanitization within the web administration interface of the XR500 devices. Attackers can exploit this weakness by sending specially crafted HTTP requests that contain malicious payloads to specific endpoints within the device's web server. These requests bypass authentication mechanisms entirely and directly invoke system commands through vulnerable input handling routines. The flaw essentially allows an attacker to inject and execute arbitrary shell commands on the underlying operating system of the router, which runs a Linux-based embedded system. This type of vulnerability is categorized under CWE-77 and CWE-94, representing improper input validation and command injection respectively, both of which are fundamental security weaknesses that enable attackers to gain unauthorized control over affected systems.
The operational impact of CVE-2018-21116 extends far beyond simple unauthorized access, as it provides attackers with complete control over the affected network infrastructure. Once exploited, attackers can establish persistent backdoors, modify network configurations, intercept and manipulate network traffic, and potentially use the compromised device as a pivot point to attack other systems within the local network. The vulnerability's unauthenticated nature means that attackers can exploit it from anywhere on the internet without needing to know any passwords or credentials, making it particularly dangerous for residential and small office deployments where such devices often lack proper network segmentation. The compromised router can serve as a command and control center for botnet activities, DNS tunneling, or as an entry point for more sophisticated attacks targeting connected IoT devices and internal systems. This aligns with ATT&CK techniques such as T1059 for command and scripting interpreter and T1021 for remote services, which describe how attackers can establish persistent access and execute commands on compromised systems.
Mitigation strategies for this vulnerability require immediate firmware updates to version 2.3.2.32 or later, which contain patches addressing the input validation flaws in the web interface. Network administrators should also implement additional protective measures including disabling remote management features when not actively needed, implementing strict firewall rules to restrict access to the router's administrative interface, and regularly monitoring network traffic for suspicious activity. Organizations should consider segmenting their networks to limit the potential impact of a compromised router, and deploying intrusion detection systems that can identify anomalous patterns consistent with exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date firmware in network infrastructure devices, as outdated embedded systems often contain unpatched security flaws that can be easily exploited by threat actors. Regular vulnerability assessments and security audits of network infrastructure components remain essential practices to identify and remediate similar weaknesses before they can be exploited in real-world scenarios.