CVE-2018-21172 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, WNDR4300 before 1.0.2.94, WNDR4300v2 before 1.0.0.50, WNDR4500v3 before 1.0.0.50, and WNR2000v5 before 1.0.0.62.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow flaw in NETGEAR router firmware that enables authenticated users to execute arbitrary code on affected devices. The issue stems from improper input validation within the web administration interface of multiple router models, creating a pathway for privilege escalation and remote code execution. The vulnerability affects a wide range of NETGEAR routers including the R7800, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, WNDR4500v3, and WNR2000v5 models across various firmware versions. The flaw occurs when the device processes user-supplied input without adequate bounds checking, allowing an authenticated attacker to overwrite adjacent memory locations on the stack. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a high-risk vulnerability in the Common Weakness Enumeration catalog. The ATT&CK framework categorizes this as a privilege escalation technique through exploitation of software vulnerabilities, specifically targeting the system configuration and credential access phases of an attack lifecycle. The impact extends beyond simple code execution to potentially enable full system compromise, including persistent backdoor installation, network traffic interception, and lateral movement capabilities within the compromised network environment.
The technical implementation of this vulnerability involves the manipulation of input parameters within the router's web interface, specifically targeting memory allocation patterns that do not properly validate the length of user-provided data. When an authenticated user submits malicious input to specific administrative functions, the firmware fails to check buffer boundaries before copying data to stack memory locations. This allows the attacker to overwrite return addresses, function pointers, and other critical stack variables, potentially redirecting execution flow to malicious code injected by the attacker. The affected firmware versions demonstrate a pattern of inadequate input sanitization that has persisted across multiple router generations, indicating a systemic issue in the development and quality assurance processes. The vulnerability's exploitation requires an authenticated session, meaning an attacker must first obtain valid login credentials, typically through social engineering, credential reuse, or prior compromise of network access. However, once authenticated, the attacker can leverage this vulnerability to gain root access to the device, effectively taking complete control over the router's operations and network configuration.
The operational impact of this vulnerability extends far beyond the immediate compromise of individual devices, as routers serve as critical network infrastructure components that control traffic flow, enforce security policies, and provide network access for multiple connected devices. Compromised routers can be used as persistent footholds for broader network attacks, enabling man-in-the-middle attacks, DNS hijacking, traffic redirection, and the establishment of command and control channels. The affected devices typically operate continuously in network environments, making them ideal targets for long-term surveillance and data exfiltration operations. Network administrators face significant challenges in identifying and remediating this vulnerability, as the affected devices may be deployed in remote locations or managed by third-party vendors, complicating the update and patching process. The vulnerability's presence in multiple router models also suggests that organizations may have widespread exposure across their network infrastructure, potentially affecting hundreds or thousands of devices simultaneously. Security teams must consider the possibility of lateral movement within networks, as compromised routers often serve as gateways to internal network segments, providing attackers with elevated privileges and access to sensitive resources.
Mitigation strategies for this vulnerability require immediate firmware updates from NETGEAR, which should include proper input validation, stack canaries, and address space layout randomization to prevent successful exploitation. Organizations should implement network segmentation to limit the impact of potential compromises and establish robust monitoring for unusual network traffic patterns that may indicate router compromise. Network administrators should conduct comprehensive inventory audits to identify all affected devices and ensure timely patch deployment across all network infrastructure. Additional protective measures include implementing strong authentication controls, regular credential rotation, and network access control lists to limit access to administrative interfaces. The vulnerability highlights the importance of secure software development practices, including code reviews, input validation, and regular security testing, as outlined in industry standards such as the OWASP Top 10 and NIST Cybersecurity Framework. Organizations should also consider implementing network intrusion detection systems to identify potential exploitation attempts and establish incident response procedures specifically tailored to router compromise scenarios. Regular security assessments and vulnerability scanning should be conducted to identify similar vulnerabilities in other network equipment and ensure comprehensive protection against similar attack vectors.