CVE-2018-21182 in R7800
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects R7800 before 1.0.2.40, R9000 before 1.0.2.52, WNDR3700v4 before 1.0.2.92, and WNDR4300 before 1.0.2.94.
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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 the R7800 R9000 WNDR3700v4 and WNDR4300 series. The issue stems from insufficient input validation within the device's web administration interface, specifically when processing user-supplied data through HTTP POST requests. An authenticated attacker with valid credentials can exploit this vulnerability by crafting malicious input parameters that exceed the allocated buffer space, leading to arbitrary code execution on the affected devices. The vulnerability is particularly concerning because it requires only authentication credentials rather than physical access, making it accessible to attackers who have gained administrative access to the device or who can obtain valid login credentials through social engineering or other means.
The technical implementation of this buffer overflow occurs within the device's web server component that handles configuration updates and administrative commands. When processing user input through the web interface, the application fails to properly validate the length of incoming data before copying it into fixed-size buffers on the stack. This allows an attacker to overwrite adjacent memory locations including return addresses and function pointers, potentially enabling complete system compromise. The vulnerability is classified as a CWE-121 stack-based buffer overflow, which falls under the broader category of memory safety issues that have historically been exploited for privilege escalation and remote code execution attacks. The specific nature of the flaw means that successful exploitation could allow an attacker to execute arbitrary code with the highest privileges available to the web server process, typically equivalent to root access on the device.
The operational impact of this vulnerability extends beyond simple exploitation as it fundamentally compromises the security posture of the affected network infrastructure. Devices that are vulnerable to this flaw become potential entry points for attackers seeking to establish persistent access to corporate or residential networks, as they can be used to create backdoors, redirect traffic, or serve as launch points for further attacks against connected systems. Network administrators who are unaware of the vulnerability may continue to use these devices without proper security controls, exposing their entire network infrastructure to compromise. The affected models represent a significant portion of NETGEAR's consumer and small business product lines, making this vulnerability particularly widespread and dangerous. The vulnerability also demonstrates the importance of proper input validation and memory management practices in embedded systems and network devices where resource constraints may lead to insufficient security controls.
Mitigation strategies for this vulnerability should include immediate firmware updates from NETGEAR to address the buffer overflow issue, as well as network segmentation to limit the potential impact of exploitation. Organizations should implement strict access controls and monitoring for administrative interfaces, ensuring that only authorized personnel have access to these critical management functions. The vulnerability aligns with several ATT&CK techniques including privilege escalation and persistence mechanisms, as attackers who exploit this flaw could establish long-term access to network infrastructure. Network defenders should also consider implementing intrusion detection systems to monitor for unusual administrative activity and malformed HTTP requests that might indicate exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify other potentially vulnerable devices within the network infrastructure, as this vulnerability may indicate broader security issues within the device's implementation that could lead to additional attack vectors.