CVE-2018-21097 in WAC505
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects WAC505 before 5.0.5.4, WAC510 before 5.0.5.4, WAC120 before 2.1.7, WN604 before 3.3.10, WNAP320 before 3.7.11.4, WNAP210v2 before 3.7.11.4, WNDAP350 before 3.7.11.4, WNDAP360 before 3.7.11.4, WNDAP660 before 3.7.11.4, WNDAP620 before 2.1.7, and WND930 before 2.1.5.
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Analysis
by VulDB Data Team • 05/06/2025
This vulnerability represents a critical stack-based buffer overflow flaw affecting multiple NETGEAR wireless access point and router models, including the WAC505, WAC510, WAC120, and various WNAP and WNDAP series devices. The vulnerability stems from insufficient input validation within the affected devices' web interface handling mechanisms, specifically when processing HTTP requests containing malformed data. An unauthenticated attacker can exploit this flaw by sending specially crafted requests to the device's web management interface, potentially leading to arbitrary code execution or complete device compromise. The vulnerability exists due to improper bounds checking in the memory allocation routines, allowing attackers to overwrite adjacent stack memory locations with malicious data.
The technical implementation of this buffer overflow occurs during the processing of HTTP POST requests to the device's web server component, where user-supplied input is directly copied to a fixed-size stack buffer without adequate length verification. This flaw aligns with CWE-121 Stack-based Buffer Overflow, which occurs when a program writes data beyond the bounds of a fixed-length stack buffer, potentially corrupting adjacent memory locations including return addresses and function parameters. The vulnerability is particularly dangerous because it requires no authentication credentials, making it accessible to anyone on the network who can reach the device's management interface. Attackers can leverage this weakness to execute arbitrary code with the privileges of the web server process, typically running with system-level privileges on the affected devices.
The operational impact of this vulnerability extends beyond simple device compromise, as it enables attackers to gain persistent access to the network infrastructure. Once exploited, attackers can modify device configurations, redirect traffic, install backdoors, or use the compromised devices as launch points for further attacks within the network. This vulnerability directly maps to several ATT&CK techniques including T1059 Command and Scripting Interpreter for code execution, T1046 Network Service Scanning to identify vulnerable targets, and T1071 Application Layer Protocol for communication through the affected web interface. The widespread nature of the affected device models means that network administrators across various sectors, from enterprise environments to residential networks, face potential exposure to this threat.
Mitigation strategies should prioritize immediate firmware updates to versions containing patches for the buffer overflow vulnerability, with particular attention to the specific version numbers mentioned in the CVE description. Network segmentation and access control measures should be implemented to restrict direct access to device management interfaces from untrusted networks, while implementing network monitoring to detect anomalous traffic patterns indicative of exploitation attempts. Device administrators should also consider disabling unnecessary web management interfaces, implementing strong authentication mechanisms, and conducting regular security audits of network infrastructure. The vulnerability demonstrates the importance of secure coding practices and proper input validation in embedded network devices, highlighting how seemingly minor implementation flaws can result in significant security risks for critical network infrastructure components.