CVE-2018-21197 in D7800
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D7800 before 1.0.1.34, R6100 before 1.0.1.22, R7500 before 1.0.0.122, R7500v2 before 1.0.3.26, R7800 before 1.0.2.40, R9000 before 1.0.2.52, 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 that affects multiple NETGEAR router models, specifically those listed in the affected versions. The vulnerability exists within the web-based management interface of these devices, where an authenticated user can exploit a buffer overflow condition in the handling of HTTP requests. This particular flaw falls under the category of CWE-121 Stack-based Buffer Overflow, which occurs when a program writes data beyond the boundaries of a fixed-length buffer allocated on the stack. The vulnerability is particularly concerning because it requires only authentication to the device's web interface, meaning that any user with valid credentials can potentially exploit this weakness to execute arbitrary code on the affected devices.
The technical implementation of this vulnerability stems from improper bounds checking within the device's web server component that processes user input through HTTP parameters. When an authenticated user submits a specially crafted HTTP request containing oversized input data, the application fails to validate the length of the input against the allocated buffer space, resulting in a stack overflow condition. This overflow can overwrite adjacent memory locations including return addresses and control data, potentially allowing an attacker to redirect execution flow and execute malicious code. The vulnerability affects a wide range of NETGEAR routers including popular models such as the D7800, R6100, R7500, R7800, and others, indicating a systemic flaw in the software implementation across multiple device families.
The operational impact of this vulnerability extends beyond simple code execution, as it provides a pathway for attackers to gain persistent control over affected network infrastructure. Once exploited, the attacker could potentially modify router configurations, redirect network traffic, establish backdoors, or use the compromised device as a pivot point for attacking other systems within the local network. This makes the vulnerability particularly dangerous in enterprise and home network environments where routers serve as critical gateway devices. The fact that these devices are often deployed in unattended environments increases the risk, as administrators may not regularly update firmware or monitor for signs of compromise. The vulnerability also creates opportunities for attackers to use these devices in larger attack campaigns, such as launching DDoS attacks or serving as command and control servers for botnets, as noted in various ATT&CK framework techniques related to network infrastructure compromise and lateral movement.
Mitigation strategies for this vulnerability should focus on immediate firmware updates from NETGEAR, as the vendor has released patches addressing the buffer overflow condition. Organizations should also implement network segmentation to limit the impact of potential exploitation, monitor network traffic for unusual patterns that might indicate exploitation attempts, and ensure that administrative access to these devices is properly secured with strong authentication mechanisms. Additionally, regular vulnerability assessments should be conducted to identify and remediate similar issues across the entire network infrastructure. The vulnerability demonstrates the importance of proper input validation and memory safety practices in embedded systems, aligning with industry best practices outlined in standards such as the CERT/CC secure coding guidelines and the OWASP Secure Coding Practices. Network administrators should also consider implementing network access control measures to prevent unauthorized access to administrative interfaces, as the vulnerability requires only authentication credentials to exploit, making it particularly dangerous in environments where weak passwords or default credentials are in use.