CVE-2018-21216 in D3600
Summary
by MITRE
Certain NETGEAR devices are affected by a buffer overflow by an unauthenticated attacker. This affects D3600 before 1.0.0.67, D6000 before 1.0.0.67, D6100 before 1.0.0.56, and R6100 before 1.0.1.20.
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Analysis
by VulDB Data Team • 06/04/2024
The vulnerability identified as CVE-2018-21216 represents a critical buffer overflow flaw affecting multiple NETGEAR wireless routers and modems within the D3600, D6000, D6100, and R6100 device families. This security weakness stems from improper input validation mechanisms within the affected firmware versions, creating an exploitable condition that allows remote code execution without requiring authentication. The vulnerability specifically impacts devices running firmware versions prior to the mentioned patches, making a substantial portion of NETGEAR's consumer and small office networking equipment susceptible to exploitation.
The technical nature of this flaw falls under CWE-121, which describes a stack-based buffer overflow condition where an attacker can write beyond the bounds of a fixed-length buffer. This type of vulnerability typically occurs when a program fails to properly check the length of input data before copying it into a limited-size buffer, allowing malicious data to overwrite adjacent memory locations. In the context of network devices, this often manifests through HTTP request parameters, network protocol parsing, or command-line argument handling within the device's web interface or network services.
The operational impact of this vulnerability extends far beyond simple network disruption, as it provides attackers with unauthorized access to the affected devices. An unauthenticated attacker can exploit this buffer overflow to execute arbitrary code on the device, potentially gaining full control over the router's functionality. This compromise enables malicious actors to modify network configurations, redirect traffic through malicious proxies, install persistent backdoors, or use the compromised device as a launching point for attacks against other systems within the local network. The implications are particularly severe for home and small office environments where these devices often serve as the primary gateway to the internet and internal network resources.
The attack surface for this vulnerability is significant given the widespread deployment of these NETGEAR device models in residential and small business environments. Network administrators and end users who have not updated their firmware to the patched versions remain at risk of exploitation, as the vulnerability does not require any credentials or prior access to the device. The lack of authentication requirements makes this particularly dangerous as attackers can exploit the vulnerability from any location on the internet, potentially affecting thousands of devices simultaneously. Organizations should consider implementing network segmentation and monitoring for unusual traffic patterns as part of their defensive posture against this type of remote exploitation.
Mitigation strategies for this vulnerability primarily involve immediate firmware updates from NETGEAR, which address the buffer overflow conditions through proper input validation and memory management. System administrators should also implement network monitoring to detect unusual patterns that might indicate exploitation attempts, particularly focusing on malformed HTTP requests or unexpected traffic flows through the affected devices. Additional defensive measures include disabling unnecessary services, implementing network access controls, and maintaining updated vulnerability scanning procedures to identify unpatched devices within the network infrastructure. The vulnerability serves as a reminder of the critical importance of timely firmware updates and proper security configuration management for network infrastructure devices, aligning with ATT&CK technique T1068 which covers exploit for privilege escalation and T1566 which covers credential harvesting through network attacks.