CVE-2018-21213 in D3600
Summary
by MITRE
Certain NETGEAR devices are affected by a buffer overflow by an unauthenticated attacker. This affects D3600 before 1.0.0.67, D6000 before 1.0.0.67, D7800 before 1.0.1.30, R6100 before 1.0.1.20, R7500 before 1.0.0.118, R7500v2 before 1.0.3.24, R7800 before 1.0.2.40, R9000 before 1.0.2.52, WNDR3700v4 before 1.0.2.96, WNDR4300 before 1.0.2.98, WNDR4300v2 before 1.0.0.50, and WNDR4500v3 before 1.0.0.50.
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Analysis
by VulDB Data Team • 06/04/2024
This vulnerability represents a critical buffer overflow flaw in NETGEAR networking equipment that exposes multiple device models to remote exploitation by unauthenticated attackers. The flaw exists in the web management interface of affected devices, specifically within the handling of HTTP request parameters that are processed without proper bounds checking. The vulnerability stems from inadequate input validation mechanisms that fail to sanitize user-supplied data before copying it into fixed-length buffers, creating a classic stack-based buffer overflow condition. This issue affects a wide range of NETGEAR routers and modems across multiple product lines including the D3600, D6000, D7800, R6100, R7500, R7500v2, R7800, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, and WNDR4500v3 models. The vulnerability is particularly concerning because it allows remote code execution without requiring any authentication credentials, making it highly attractive to attackers seeking to compromise network infrastructure.
The technical implementation of this buffer overflow occurs when the device processes HTTP requests containing specially crafted parameters that exceed the allocated buffer space. When an attacker sends a malformed request to the affected device's web interface, the system attempts to copy the excessive data into a fixed-size memory buffer without proper bounds checking, resulting in memory corruption that can be exploited to overwrite adjacent memory locations. This memory corruption can be leveraged to overwrite return addresses, function pointers, or other critical program state information, potentially allowing an attacker to execute arbitrary code with the privileges of the web server process. The vulnerability is classified as a CWE-121 stack-based buffer overflow, which is a well-documented weakness in software development practices that violates fundamental security principles of input validation and memory management. According to the ATT&CK framework, this vulnerability maps to T1210 exploitation for execution and T1072 local network mapping, as attackers can leverage this flaw to establish persistent access to network infrastructure. The flaw is particularly dangerous because it affects devices that are typically deployed in residential and small office environments where network security is often insufficient, making these devices prime targets for botnet recruitment and advanced persistent threat campaigns.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass full network compromise and potential data exfiltration capabilities. An attacker who successfully exploits this vulnerability can gain complete control over the affected device, including the ability to modify network settings, redirect traffic, establish backdoors, or use the compromised device as a pivot point to attack other systems within the local network. The affected devices typically operate with elevated privileges and have direct access to the internal network, making them ideal stepping stones for lateral movement attacks. Additionally, the vulnerability can be exploited to create persistent access points that survive device reboots, allowing attackers to maintain long-term control over the compromised network infrastructure. The affected firmware versions span multiple generations of NETGEAR devices, indicating a widespread vulnerability that has persisted across various product lines and firmware updates, suggesting either inadequate security testing during development or insufficient patching mechanisms. Organizations should consider this vulnerability as part of a broader attack surface assessment, particularly in environments where these devices are deployed without proper network segmentation or monitoring controls. The vulnerability also highlights the importance of firmware security and the need for regular security updates, as many affected devices may not receive timely patches or may be deployed in environments where patching is not regularly performed. Network defenders should implement monitoring for suspicious HTTP traffic patterns and consider deploying network-based intrusion detection systems to identify exploitation attempts against these vulnerable devices.