CVE-2018-21100 in R7800
Summary
by MITRE
NETGEAR R7800 devices before 1.0.2.60 are affected by command injection by an authenticated user.
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Analysis
by VulDB Data Team • 06/03/2024
The CVE-2018-21100 vulnerability represents a critical command injection flaw discovered in NETGEAR R7800 router devices running firmware versions prior to 1.0.2.60. This vulnerability specifically targets the web-based management interface of the device, which operates on a Linux-based embedded operating system with a web server component. The flaw allows authenticated users with access to the device's web interface to execute arbitrary commands on the underlying operating system, effectively bypassing the intended security boundaries between the user interface and the system shell. The vulnerability stems from improper input validation within the parameter handling of the web application, where user-supplied data is directly incorporated into system commands without adequate sanitization or escaping mechanisms.
The technical exploitation of this vulnerability occurs when an authenticated user submits malicious input through web forms or API endpoints that are processed by the device's command execution functions. The affected parameters typically relate to network configuration settings, diagnostic commands, or system utilities that the web interface uses to communicate with the underlying operating system. When these parameters contain shell metacharacters or command separators such as semicolons, ampersands, or backticks, the system executes the injected commands with the privileges of the web server process, which typically runs with administrative privileges on the device. This creates a path for attackers to escalate their privileges and gain full control over the router's functionality, potentially leading to persistent access, network reconnaissance, or further exploitation of connected devices.
The operational impact of this vulnerability extends beyond simple command execution, as it fundamentally compromises the security model of the device and creates opportunities for broader network compromise. An attacker who gains access through this vulnerability can potentially modify firewall rules, redirect traffic, establish backdoors, or use the router as a pivot point to attack other devices within the local network. The vulnerability also poses risks to the confidentiality and integrity of network communications, as the attacker can potentially intercept or modify traffic passing through the compromised device. This type of vulnerability aligns with CWE-77 and CWE-88, which describe command injection flaws in input validation and parameter handling respectively, and maps to ATT&CK technique T1059.001 for command and script execution through the command shell. The vulnerability affects the device's authentication model by allowing privilege escalation through authenticated access, and it can be exploited to establish persistent access through modifications to system files or configuration parameters.
Mitigation strategies for CVE-2018-21100 primarily focus on firmware updates and network segmentation approaches. The most effective solution involves upgrading the affected NETGEAR R7800 devices to firmware version 1.0.2.60 or later, which includes proper input validation and sanitization mechanisms. Network administrators should also implement strict access controls, limiting administrative access to the device's web interface to trusted personnel only and enforcing strong authentication mechanisms. Additional protective measures include disabling unnecessary services, implementing network monitoring to detect unusual command execution patterns, and conducting regular security assessments of network infrastructure. The vulnerability demonstrates the importance of proper input validation in web applications and highlights the need for defense-in-depth strategies that protect against both external and internal threats. Organizations should also consider implementing network access control lists and intrusion detection systems to monitor for potential exploitation attempts targeting similar vulnerabilities in network infrastructure devices.