CVE-2018-21204 in D7800
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects 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 • 10/13/2020
This vulnerability represents a critical stack-based buffer overflow condition that affects multiple NETGEAR router models, including the D7800, R6100, R7500, R7500v2, R7800, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, and WNDR4500v3 series. The flaw exists within the device's web interface handling mechanism, specifically in the processing of HTTP requests that contain malformed input data. An unauthenticated attacker can exploit this vulnerability by sending specially crafted requests to the affected devices, potentially leading to arbitrary code execution or complete system compromise. The vulnerability stems from insufficient input validation and bounds checking within the router's firmware, allowing attackers to overflow the stack buffer and overwrite critical memory locations.
The technical implementation of this vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which occurs when a program writes data beyond the boundaries of a fixed-length stack buffer. This particular flaw affects devices running firmware versions prior to the specified patches, with each model having its own version threshold for vulnerability exposure. The attack vector is particularly concerning because it requires no authentication, meaning that an attacker can exploit this vulnerability from outside the network perimeter. The buffer overflow can potentially be leveraged to overwrite return addresses, function pointers, or other critical program state information, enabling attackers to redirect execution flow and execute malicious code. This type of vulnerability falls under the ATT&CK technique T1059.007 Command and Scripting Interpreter, as it can lead to remote code execution and system compromise.
The operational impact of this vulnerability extends beyond simple device compromise, as affected routers serve as critical network infrastructure components that control access to entire networks. When exploited, the vulnerability can provide attackers with persistent access to the internal network, potentially enabling further reconnaissance, lateral movement, and data exfiltration activities. The attack surface is particularly broad given that these devices are commonly deployed in residential and small office environments where network security may be inadequate. Organizations using these vulnerable devices face significant risk of unauthorized network access, potential data breaches, and service disruption. The vulnerability's unauthenticated nature makes it especially dangerous as it can be exploited by remote attackers without requiring any prior access credentials or network privileges.
Mitigation strategies for this vulnerability require immediate firmware updates from NETGEAR, with affected devices upgraded to the patched versions specified in the vendor advisories. Network administrators should prioritize updating all affected router models to their latest firmware releases, as these patches include proper input validation and bounds checking mechanisms that prevent the buffer overflow condition. Additionally, network segmentation and access control measures should be implemented to limit the potential impact of exploitation, including restricting direct internet access to router management interfaces. Organizations should also consider deploying network monitoring solutions to detect anomalous traffic patterns that might indicate exploitation attempts. The vulnerability highlights the importance of regular firmware updates and network security assessments, particularly for critical infrastructure devices that may be exposed to external threats. Compliance with security standards such as NIST SP 800-53 and ISO 27001 requires organizations to maintain updated security configurations and promptly address known vulnerabilities to prevent unauthorized access and maintain network integrity.