CVE-2019-20682 in D3600
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects D3600 before 1.0.0.76, D6000 before 1.0.0.76, D6200 before 1.1.00.32, D7000 before 1.0.1.68, JR6150 before 1.0.1.18, PR2000 before 1.0.0.28, R6020 before 1.0.0.38, R6050 before 1.0.1.18, R6080 before 1.0.0.38, R6120 before 1.0.0.46, R6220 before 1.1.0.80, R6260 before 1.1.0.40, R6700v2 before 1.2.0.36, R6800 before 1.2.0.36, R6900v2 before 1.2.0.36, WNR2020 before 1.1.0.62, and XR500 before 2.3.2.32.
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Analysis
by VulDB Data Team • 05/27/2024
This vulnerability represents a critical stack-based buffer overflow flaw in NETGEAR router firmware that exposes numerous consumer and enterprise networking devices to remote exploitation. The flaw exists within the web interface handling of specific router models, allowing unauthenticated attackers to craft malicious requests that can overwrite adjacent memory locations on the device's stack. Such buffer overflow conditions occur when programs write more data to a fixed-length buffer than it can accommodate, leading to potential memory corruption that can be leveraged for arbitrary code execution. The affected devices span multiple product lines including the D3600, D6000, R6020, R6050, and R6800 series, among others, with firmware versions prior to the specified patches being vulnerable. The vulnerability is particularly concerning because it requires no authentication to exploit, making it accessible to any attacker with network access to the device, and the affected firmware versions were widely deployed in residential and small office environments.
The technical exploitation of this vulnerability follows established patterns for stack-based buffer overflows, typically involving the manipulation of input parameters within HTTP requests or web interface forms. Attackers can craft specially formatted requests that cause the device's web server process to write beyond the bounds of allocated memory buffers, potentially overwriting return addresses, function pointers, or other critical stack data structures. When combined with proper memory layout knowledge or through techniques like return-oriented programming, this overflow can redirect execution flow to malicious code injected by the attacker. The vulnerability's classification aligns with CWE-121 Stack-based Buffer Overflow, which is a well-documented weakness in software design that consistently leads to privilege escalation and system compromise. This weakness is particularly dangerous in embedded devices because these systems often lack modern exploit mitigation techniques such as stack canaries, address space layout randomization, or non-executable stack protections, making exploitation more reliable and predictable.
The operational impact of this vulnerability extends beyond simple device compromise, as affected routers serve as critical network infrastructure components that can provide attackers with persistent access to entire networks. Once exploited, attackers can gain full control over the affected devices, potentially enabling them to modify network configurations, intercept traffic, redirect DNS requests, or establish backdoor access for further network infiltration. The widespread deployment of these vulnerable devices across residential and small business networks creates a substantial attack surface that could be leveraged for large-scale network compromise or as a staging point for broader attacks. The vulnerability's presence in multiple router models suggests a systemic issue in the firmware development process, indicating that similar flaws may exist in other components or versions of NETGEAR's products. Organizations relying on these devices for network security may find their firewall and network segmentation capabilities compromised, as attackers could potentially bypass network controls by taking control of the routers themselves. The attack vector is particularly insidious because it requires no specialized credentials or physical access, making it accessible to threat actors with basic network reconnaissance capabilities.
Mitigation strategies for this vulnerability must address both immediate device protection and long-term firmware security improvements. The primary and most effective mitigation is to update all affected devices to the latest firmware versions provided by NETGEAR, which contain patches that address the buffer overflow conditions. Network administrators should implement network segmentation and access controls to limit the potential impact of device compromise, while also monitoring network traffic for signs of exploitation attempts. The vulnerability's characteristics make it particularly suitable for exploitation through automated scanning tools, so organizations should consider implementing network-based intrusion detection systems to monitor for known exploit signatures. Device vendors should also implement proper input validation and bounds checking in their firmware development processes, following secure coding practices that prevent buffer overflow conditions from occurring in the first place. Regular firmware update policies and network monitoring procedures should be established to ensure that similar vulnerabilities are identified and addressed promptly. Organizations should also consider implementing network access control measures that limit which devices can communicate with router management interfaces, reducing the attack surface for unauthenticated access. The vulnerability serves as a reminder of the importance of maintaining up-to-date embedded device firmware and the critical need for security testing in network infrastructure components.