CVE-2018-21149 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, DM200 before 1.0.0.50, R6100 before 1.0.1.22, R7500 before 1.0.0.122, R7800 before 1.0.2.42, R8900 before 1.0.3.10, R9000 before 1.0.3.10, WNDR3700v4 before 1.0.2.96, WNDR4300 before 1.0.0.54, WNDR4300v2 before 1.0.0.54, WNDR4500v3 before 1.0.0.54, and WNR2000v5 before 1.0.0.64.
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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, including popular consumer and enterprise grade devices. The vulnerability stems from insufficient input validation within the device's web interface handling mechanisms, specifically when processing user-supplied data through authenticated administrative functions. The flaw exists in the firmware implementations of various D7800, R6100, R7500, R7800, R8900, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, WNDR4500v3, and WNR2000v5 models, with affected versions prior to the specified firmware updates. According to CWE-121, this vulnerability falls under the category of stack-based buffer overflow conditions where insufficient bounds checking allows attackers to write data beyond the allocated buffer space on the stack. The authenticated nature of this vulnerability means that an attacker must first establish valid credentials to exploit the flaw, typically through legitimate administrative access or by compromising existing user accounts.
The technical execution of this vulnerability occurs when an authenticated user submits maliciously crafted input to web interface parameters that control administrative functions within the router's firmware. The buffer overflow can be triggered through HTTP requests that manipulate form fields, URL parameters, or API endpoints used for configuration management. When the vulnerable code processes this input without proper bounds checking, it overflows the allocated stack buffer and can overwrite adjacent memory locations including return addresses, function pointers, or other critical program state information. This memory corruption can potentially lead to arbitrary code execution, allowing attackers to gain unauthorized control over the device, modify network configurations, or establish persistent backdoors. The vulnerability's impact extends beyond simple privilege escalation as it represents a fundamental security flaw that can be exploited to compromise the entire network infrastructure managed by the affected routers.
The operational impact of this vulnerability is severe and multifaceted, as compromised routers can serve as persistent entry points for network attackers. Once exploited, the vulnerability allows attackers to execute arbitrary commands on the affected devices with the highest privilege level available to the authenticated user, typically equivalent to root access within the router's operating system. This can result in complete network takeover, enabling attackers to monitor traffic, redirect connections, disable security features, or use the compromised device as a launch point for attacks against other networked systems. The widespread deployment of affected NETGEAR models across both residential and commercial networks means that a successful exploitation could affect thousands of devices simultaneously, creating a significant threat vector for large-scale network intrusions. The vulnerability also poses risks to supply chain security, as compromised devices could be used to create botnets or serve as persistent footholds for advanced persistent threats.
Mitigation strategies for this vulnerability must be implemented immediately through firmware updates provided by NETGEAR, which address the buffer overflow conditions through proper input validation and bounds checking mechanisms. Network administrators should ensure all affected devices receive the latest firmware versions that include patches addressing the specific buffer overflow conditions in the web interface handling code. Additional security measures include implementing strong authentication controls, regularly monitoring network traffic for suspicious activity, and deploying network segmentation to limit the potential impact of compromised devices. Organizations should also consider disabling unnecessary web interface access where possible and implementing multi-factor authentication for administrative access. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence, specifically T1068 for locally executed malicious code and T1078 for valid accounts. Regular security assessments and vulnerability scanning should be conducted to identify any remaining unpatched devices within the network infrastructure, as the vulnerability's authenticated nature means that compromised administrative accounts could remain undetected for extended periods.