CVE-2018-21151 in D7800
Summary
by MITRE
Certain NETGEAR devices are affected by a buffer overflow by an authenticated user. This affects D7800 before 1.0.1.34, R7500v2 before 1.0.3.26, R7800 before 1.0.2.42, R8900 before 1.0.3.10, R9000 before 1.0.3.10, WNDR4300v2 before 1.0.0.54, and WNDR4500v3 before 1.0.0.54.
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Analysis
by VulDB Data Team • 06/01/2024
This vulnerability represents a critical buffer overflow flaw in NETGEAR router firmware that allows authenticated attackers to execute arbitrary code on affected devices. The issue stems from improper input validation within the web administration interface of multiple router models, creating a condition where user-supplied data can overflow allocated memory buffers. The vulnerability affects a wide range of NETGEAR devices including the D7800, R7500v2, R7800, R8900, R9000, WNDR4300v2, and WNDR4500v3 models across their respective firmware versions. The authenticated nature of this vulnerability means that an attacker must first obtain valid credentials to exploit the flaw, though this presents a significant risk since many users operate routers with default or weak administrative passwords.
The technical implementation of this buffer overflow occurs within the web server component of the router firmware, specifically when processing HTTP requests containing malformed input data. When an authenticated user submits crafted input to specific parameters within the administration interface, the router fails to properly bounds-check the incoming data before copying it into fixed-size memory buffers. This allows attackers to overwrite adjacent memory locations, potentially corrupting program execution flow and enabling arbitrary code execution with the privileges of the web server process. The vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking permits access beyond the boundaries of allocated memory blocks. This type of vulnerability creates a direct path for privilege escalation and remote code execution attacks.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally compromises the security posture of affected networks. Once exploited, attackers can gain complete administrative control over the affected routers, enabling them to modify network configurations, redirect traffic, install malware, or establish persistent backdoors. The compromised router can then serve as a pivot point for lateral movement within the network, potentially allowing attackers to access connected devices and internal systems. This vulnerability particularly affects enterprise and home networks where router security is often overlooked, creating a significant risk for organizations relying on these devices for network perimeter protection. The attack surface is further expanded due to the widespread deployment of these affected models, making them attractive targets for automated exploitation campaigns.
Mitigation strategies for this vulnerability require immediate firmware updates from NETGEAR to address the buffer overflow conditions in the affected router models. Organizations should prioritize updating all affected devices to the latest firmware versions that contain patches for this vulnerability, particularly focusing on the specific version numbers mentioned in the advisory. Network administrators should implement additional security controls including disabling unnecessary services, enforcing strong authentication mechanisms, and monitoring for suspicious network activity. The vulnerability demonstrates the importance of secure coding practices and proper input validation, aligning with ATT&CK technique T1059.007 for command and scripting interpreter usage. Regular security assessments and firmware update procedures should be implemented to prevent similar vulnerabilities from being introduced in future deployments. Network segmentation and monitoring solutions can help detect exploitation attempts and limit the impact of successful attacks on affected devices.