CVE-2018-21157 in D7800
Summary
by MITRE
Certain NETGEAR devices are affected by command injection by an authenticated user. This affects D7800 before 1.0.1.28, R6700 before 1.0.1.44, R6900 before 1.0.1.44, R7000 before 1.0.9.28, R7500v2 before 1.0.3.24, R7800 before 1.0.2.38, R9000 before 1.0.2.52, WNDR4300v2 before 1.0.0.50, and WNDR4500v3 before 1.0.0.50.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical command injection flaw in NETGEAR router firmware that allows authenticated users to execute arbitrary commands on affected devices. The issue stems from insufficient input validation within the web administration interface of multiple router models, creating a pathway for privilege escalation through crafted user input. The affected devices span several popular NETGEAR router series including the D7800, R6700, R6900, R7000, R7500v2, R7800, R9000, WNDR4300v2, and WNDR4500v3 models. The vulnerability exists in firmware versions prior to the specified patches, with each model requiring different minimum firmware versions for remediation. This authentication-based command injection vulnerability aligns with CWE-77, which specifically addresses command injection flaws where user-supplied data is directly incorporated into system commands without proper sanitization.
The technical exploitation of this vulnerability occurs through the web-based administration interface where authenticated users can manipulate input fields that are subsequently processed by the device's command execution engine. When user input containing malicious commands is submitted through these interfaces, the system fails to properly sanitize or validate the input before executing it within the device's operating system context. This creates a scenario where an authenticated attacker can leverage their access privileges to execute arbitrary system commands with the same privileges as the web interface user, typically root or administrative level access. The vulnerability is particularly concerning because it requires only authentication to the device's web interface, which is often accessible to users within the local network, making it exploitable by anyone with legitimate network access.
From an operational impact perspective, this vulnerability compromises the fundamental security of network infrastructure devices by enabling attackers to gain full control over affected routers. Once exploited, attackers can modify router configurations, redirect traffic, install malware, or establish persistent backdoors within the network. The attack surface extends beyond simple command execution as the compromised router can serve as a pivot point for lateral movement within the network, potentially providing access to internal systems that would otherwise be isolated from external threats. The vulnerability affects enterprise and home networks alike, as these routers often serve as the primary gateway device for network traffic, making them critical attack vectors for network infiltration. Network security professionals must consider that these devices may be used to create persistent access points or to act as command and control servers for other network-based attacks.
Mitigation strategies for this vulnerability involve immediate firmware updates to the latest versions provided by NETGEAR, which contain proper input validation and sanitization mechanisms. Network administrators should also implement network segmentation to limit access to administrative interfaces, enforce strong authentication controls, and monitor for suspicious network activity that might indicate exploitation attempts. The vulnerability demonstrates the importance of secure coding practices and proper input validation in embedded systems, particularly in network infrastructure devices that are designed to be accessible to users while maintaining security. Organizations should also consider implementing network access control measures to restrict administrative access to these devices and establish regular patch management procedures to ensure all network infrastructure components remain up to date with security fixes. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and command execution techniques, emphasizing the need for layered security approaches to protect network infrastructure devices from authenticated attack vectors.