CVE-2018-21171 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, R7800 before 1.0.2.40, R9000 before 1.0.3.6, WNDR3700v4 before 1.0.2.92, and WNDR4300 before 1.0.2.98.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow condition that affects multiple NETGEAR networking devices including the D6100, R7800, R9000, WNDR3700v4, and WNDR4300 models. The flaw exists within the device's web management interface and can be exploited by an authenticated user who has access to the device's administrative console. The vulnerability stems from improper input validation in the handling of user-supplied data within the device's firmware, specifically in the processing of HTTP requests sent to the web server component. According to CWE-121, this constitutes a classic stack-based buffer overflow where an attacker can write data beyond the bounds of a fixed-length buffer allocated on the stack, potentially leading to arbitrary code execution or system crashes.
The technical implementation of this vulnerability involves an authenticated user sending specially crafted HTTP requests to the device's web interface, which then processes these requests without proper bounds checking. When the device receives input that exceeds the allocated buffer space, it overwrites adjacent memory locations on the stack, potentially allowing an attacker to overwrite return addresses, function pointers, or other critical program data. This type of vulnerability falls under the ATT&CK technique T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, as it requires authentication but can lead to full system compromise once exploited. The specific affected firmware versions indicate that this vulnerability has existed for several firmware releases, suggesting it was not properly addressed in the development lifecycle.
The operational impact of this vulnerability extends beyond simple system instability, as it can enable complete compromise of the affected network devices. An authenticated attacker with administrative privileges could leverage this vulnerability to execute arbitrary code on the device, potentially gaining root access to the embedded operating system. This would allow the attacker to modify network configurations, redirect traffic, install malicious firmware, or use the compromised device as a pivot point for attacking other systems within the network. The vulnerability is particularly concerning because it affects enterprise-grade networking equipment that often serves as the gateway between internal networks and external internet access, making it a prime target for lateral movement attacks.
Mitigation strategies for this vulnerability should include immediate firmware updates from NETGEAR to the latest available versions that contain patches addressing the buffer overflow condition. Network administrators should ensure that all affected devices are updated promptly, as the vulnerability requires only authenticated access to exploit. Additionally, implementing network segmentation and access controls can help limit the potential impact if a device is compromised. The principle of least privilege should be enforced by restricting administrative access to only authorized personnel and implementing multi-factor authentication where possible. Regular vulnerability assessments and network monitoring should be conducted to detect any potential exploitation attempts. Organizations should also consider implementing network access control lists to limit access to device management interfaces and ensure that administrative access is only available from trusted network segments. This vulnerability demonstrates the importance of proper input validation and secure coding practices in embedded systems, aligning with industry standards that emphasize defensive programming techniques to prevent buffer overflow conditions.