CVE-2018-21193 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, D7800 before 1.0.1.34, R6100 before 1.0.1.20, R7500 before 1.0.0.122, R7500v2 before 1.0.3.24, R7800 before 1.0.2.40, 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 affecting multiple NETGEAR wireless routers and networking devices. The issue stems from insufficient input validation within the device's web interface administration functionality, specifically when processing user-supplied data through HTTP POST requests. An authenticated attacker with valid credentials can exploit this weakness by sending carefully crafted payloads that exceed the allocated buffer space, leading to memory corruption and potential arbitrary code execution. The vulnerability affects a wide range of devices including the D6100, D7800, R6100, R7500 series, R7500v2, R7800, WNDR3700v4, WNDR4300, WNDR4300v2, WNDR4500v3, and WNR2000v5 models. The affected firmware versions indicate that this flaw has persisted across multiple generations of these networking devices, suggesting a fundamental design issue in the input handling mechanisms. The stack-based nature of the overflow means that the attacker can overwrite adjacent memory locations including return addresses and function pointers, potentially allowing complete system compromise.
The technical exploitation of this vulnerability aligns with CWE-121 stack-based buffer overflow classification, where insufficient bounds checking permits data to overwrite adjacent stack memory. This type of vulnerability falls under the ATT&CK framework's technique T1059.007 for command and scripting interpreter execution, as successful exploitation could enable attackers to execute arbitrary commands on the affected devices. The authenticated nature of the attack requires the adversary to first obtain valid administrative credentials, which may be achieved through credential reuse, weak password policies, or other initial compromise techniques. However, the low privilege requirement for exploitation makes this particularly concerning as it can be leveraged by attackers who have already gained access to the device through other means. The memory corruption impacts typically manifest as application crashes, system instability, or complete system takeover, depending on the precise memory locations overwritten during the overflow condition.
The operational impact of this vulnerability extends beyond simple device compromise, as these networking devices serve as critical infrastructure components within both residential and enterprise environments. When exploited, the vulnerability can result in complete network control, enabling attackers to redirect traffic, implement man-in-the-middle attacks, or establish persistent backdoors. The affected devices often serve as the primary gateway for network access, making them attractive targets for attackers seeking long-term access to larger network segments. Additionally, the vulnerability's persistence across multiple firmware versions suggests that many devices may remain unpatched in the field, creating a widespread attack surface. The exploitation could also enable attackers to modify device configurations, disable security features, or use the compromised devices as launching points for attacks against other systems. Organizations may experience service disruption, data exfiltration, or unauthorized network access that could compromise the entire network infrastructure depending on the device's role and the attacker's objectives.
Mitigation strategies should focus on immediate firmware updates from NETGEAR, as these contain the necessary patches to address the buffer overflow conditions. Network segmentation and access control should be implemented to limit the attack surface, ensuring that only authorized personnel can access device administration interfaces. Regular credential audits and strong authentication mechanisms including multi-factor authentication should be enforced to reduce the likelihood of unauthorized access. Network monitoring should be enhanced to detect anomalous traffic patterns that may indicate exploitation attempts or compromised devices. Device hardening practices including disabling unnecessary services, applying firewall rules, and regularly reviewing access logs should be implemented. Organizations should also consider implementing network intrusion detection systems to monitor for exploitation attempts and maintain detailed inventory records of all affected devices to ensure comprehensive remediation. The vulnerability demonstrates the importance of proper input validation and memory management in embedded systems, highlighting the need for security-focused development practices and regular security assessments of network infrastructure devices.