CVE-2018-21196 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, R6100 before 1.0.1.20, R7800 before 1.0.2.40, R9000 before 1.0.2.52, WNDR3700v4 before 1.0.2.92, WNDR4300 before 1.0.2.94, 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 that affects multiple NETGEAR wireless routers and networking devices, specifically targeting models including the D6100, R6100, R7800, R9000, WNDR3700v4, WNDR4300, and WNR2000v5. The vulnerability is particularly concerning because it requires only authenticated access to exploit, meaning an attacker who has already gained user-level credentials can leverage this flaw to execute arbitrary code on the affected devices. The affected firmware versions demonstrate a pattern of insufficient input validation and memory management practices that create opportunities for attackers to overwrite stack memory locations. This type of vulnerability falls under CWE-121 which specifically addresses stack-based buffer overflow conditions, where insufficient boundary checking allows attackers to write beyond the allocated buffer space and potentially overwrite adjacent memory locations including return addresses and function pointers. The impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with the ability to completely compromise the affected networking equipment, potentially leading to full network infiltration and persistent access to the underlying infrastructure.
The technical exploitation of this buffer overflow occurs when authenticated users submit malicious input to specific application interfaces within the device's web administration portal or management services. Attackers can craft inputs that exceed the allocated buffer space, causing the stack to overflow and potentially redirecting execution flow to malicious code locations. This type of vulnerability is particularly dangerous in network infrastructure devices because these routers often serve as gateways to internal networks, providing attackers with potential lateral movement capabilities. The exploitation process typically involves carefully constructed payloads that can overwrite the instruction pointer or other critical stack variables, allowing attackers to execute arbitrary code with the privileges of the affected process. This aligns with ATT&CK technique T1059 which covers command and scripting interpreter usage, and T1071 which addresses application layer protocols, as the exploitation leverages legitimate application interfaces to achieve malicious code execution. The authentication requirement means that attackers must first obtain valid user credentials through social engineering, credential stuffing, or other initial compromise techniques, but once achieved, the vulnerability provides a powerful escalation path.
The operational impact of this vulnerability is severe for organizations relying on affected NETGEAR devices, as successful exploitation can result in complete device compromise and potential network infiltration. Attackers can gain persistent access to the affected routers, potentially enabling them to monitor network traffic, redirect DNS requests, modify firewall rules, or establish backdoor access to the internal network. The vulnerability affects devices that are commonly deployed in both enterprise and residential environments, making it particularly dangerous as it could be exploited by attackers targeting home networks or corporate infrastructure. Organizations may experience service disruption, data exfiltration, or unauthorized network access that could go undetected for extended periods. The affected firmware versions indicate that this vulnerability has persisted across multiple generations of devices, suggesting that the underlying memory management flaws were not properly addressed in firmware updates, potentially leaving organizations vulnerable even after applying patches. Network security monitoring systems may not detect exploitation attempts if the malicious activity appears as legitimate administrative operations, further complicating incident response efforts.
Mitigation strategies for this vulnerability should begin with immediate firmware updates from NETGEAR to the latest available versions that contain patches addressing the buffer overflow condition. Organizations should also implement network segmentation to limit the potential impact of device compromise and establish robust access controls to prevent unauthorized administrative access. Network monitoring should include inspection of unusual administrative activities and unexpected changes to router configurations that could indicate exploitation attempts. Security teams should consider implementing network access control lists to restrict access to administrative interfaces and ensure that only authorized personnel can access sensitive management functions. Regular vulnerability assessments and penetration testing should be conducted to identify similar issues in other networking equipment and ensure that all devices are running patched firmware versions. Additionally, organizations should establish incident response procedures specifically designed to handle compromised network infrastructure devices, including protocols for device isolation, forensic analysis, and network reconfiguration. The vulnerability highlights the importance of maintaining current firmware versions and implementing defense-in-depth strategies that reduce the attack surface of critical networking infrastructure devices.