CVE-2018-21191 in D6100
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D6100 before 1.0.0.57, R6100 before 1.0.1.20, R7800 before 1.0.2.40, WNDR3700v4 before 1.0.2.92, WNDR4300 before 1.0.2.94, WNDR4300v2 before 1.0.0.50, WNDR4500v3 before 1.0.0.50, and WNR2000v5 before 1.0.0.62.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow flaw in NETGEAR networking equipment that enables authenticated users to execute arbitrary code on affected devices. The issue stems from insufficient input validation within the device's web interface handling mechanisms, specifically affecting multiple router models including D6100, R6100, R7800, and various WNDR series devices. The vulnerability exists in the device's firmware implementation where user-supplied data is copied to a fixed-size buffer without proper bounds checking, creating a condition where malicious input can overwrite adjacent memory locations on the stack. This flaw allows an attacker who has already gained authentication credentials to potentially escalate privileges and execute malicious code with the same privileges as the web server process, which typically runs with elevated system permissions.
The technical exploitation of this vulnerability requires an authenticated user to send specifically crafted input to the device's web management interface through HTTP requests. The buffer overflow occurs when the device processes user input that exceeds the allocated buffer space, causing a stack corruption that can be leveraged to overwrite return addresses and function pointers. This type of vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which is classified under the Common Weakness Enumeration catalog as a fundamental flaw in memory management practices. The attack vector is particularly concerning because it requires only authentication, which is often easily obtained through default credentials or social engineering attacks, making the exploitation more accessible to threat actors. According to ATT&CK framework, this vulnerability aligns with T1059.007 Command and Scripting Interpreter: PowerShell and T1068 Exploitation for Privilege Escalation, as it allows for code execution and privilege elevation within the network infrastructure.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally compromises the integrity and security of the affected network infrastructure. Network administrators face significant risk when these devices are compromised, as attackers can potentially establish persistent backdoors, monitor network traffic, redirect traffic to malicious sites, or use the compromised device as a launch point for further attacks within the network. The affected devices operate as core network infrastructure components, making their compromise particularly dangerous for enterprise and home networks alike. Organizations using these vulnerable devices may experience complete loss of network control, data exfiltration, or disruption of network services, with potential cascading effects throughout the connected network ecosystem. The vulnerability affects devices that are commonly deployed in both residential and enterprise environments, increasing the potential attack surface and impact scope.
Mitigation strategies for this vulnerability must include immediate firmware updates from NETGEAR to address the buffer overflow condition, with administrators prioritizing the patching of all affected device models. The recommended approach involves verifying the current firmware versions against NETGEAR's official release notes and applying the appropriate security patches that correct the input validation flaws in the web interface handling code. Network segmentation and access control measures should be implemented to limit the potential impact of successful exploitation, including restricting administrative access to only necessary personnel and implementing multi-factor authentication. Additionally, organizations should conduct comprehensive network audits to identify all affected devices and establish monitoring protocols to detect potential exploitation attempts. Security teams should also consider implementing network intrusion detection systems that can identify anomalous traffic patterns associated with exploitation attempts, while maintaining regular vulnerability assessments to ensure ongoing protection against similar flaws in network infrastructure devices.