CVE-2018-21111 in D3600
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an authenticated user. This affects D3600 before 1.0.0.75, D6000 before 1.0.0.75, D6100 before 1.0.0.60, R7800 before 1.0.2.52, R8900 before 1.0.4.2, R9000 before 1.0.4.2, WNDR3700v4 before 1.0.2.102, WNDR4300 before 1.0.2.104, WNDR4300v2 before 1.0.0.58, WNDR4500v3 before 1.0.0.58, and WNR2000v5 before 1.0.0.66.
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Analysis
by VulDB Data Team • 06/01/2024
This vulnerability represents a critical stack-based buffer overflow flaw that affects multiple NETGEAR router models, specifically targeting devices with firmware versions prior to the specified patches. The vulnerability occurs within the web management interface of these devices, where an authenticated user can exploit a flaw in input validation mechanisms to overwrite adjacent memory locations on the stack. This type of vulnerability falls under the common weakness enumeration CWE-121, which specifically addresses stack-based buffer overflow conditions that can lead to arbitrary code execution. The affected devices include popular models such as the D3600, D6000, R7800, and various WNDR series routers, indicating a widespread issue across NETGEAR's product portfolio.
The technical implementation of this vulnerability involves the exploitation of insufficient bounds checking in the web server component of the router firmware. When an authenticated user submits specially crafted input through the web interface, the application fails to properly validate the length of the input data before copying it into a fixed-size buffer allocated on the stack. This allows an attacker to overwrite adjacent memory locations including return addresses and function pointers, potentially enabling remote code execution or system compromise. The vulnerability is particularly concerning because it requires only authentication, which can often be obtained through default credentials or social engineering attacks. According to the attack technique framework, this represents a privilege escalation vector that can be leveraged through the technique T1078 which involves valid accounts for lateral movement and persistence.
The operational impact of this vulnerability extends beyond simple denial of service or data corruption, as it can enable full system compromise when exploited successfully. An authenticated attacker with access to the device's web interface can potentially execute arbitrary code with the privileges of the web server process, which typically runs with elevated permissions on router systems. This could allow for complete network takeover, data exfiltration, or the installation of persistent backdoors. The widespread nature of affected models means that numerous networks could be at risk, particularly in enterprise environments where default credentials are often not changed, and in residential networks where users may be unaware of the security implications. The vulnerability affects firmware versions that were widely distributed, making it a significant concern for network administrators who may not have updated their devices to the latest patches.
Mitigation strategies for this vulnerability should include immediate firmware updates from NETGEAR, which address the buffer overflow through proper input validation and bounds checking mechanisms. Network administrators should also implement strong authentication practices, including changing default credentials, enabling two-factor authentication where possible, and monitoring for unauthorized access attempts. The implementation of network segmentation and access control lists can help limit the potential impact if a device is compromised. Additionally, regular vulnerability assessments and penetration testing should be conducted to identify and remediate similar issues in network infrastructure. Security monitoring solutions should be configured to detect unusual patterns in web interface access and potential exploitation attempts, as this vulnerability can be detected through network traffic analysis and log monitoring. Organizations should also consider implementing network access control policies that limit administrative access to critical network devices and maintain detailed inventory records of all network equipment to ensure timely patch deployment.