CVE-2018-21170 in EX2700
Summary
by MITRE
Certain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects EX2700 before 1.0.1.28, R7800 before 1.0.2.40, WN2000RPTv3 before 1.0.1.20, WN3000RPv3 before 1.0.2.50, and WN3100RPv2 before 1.0.0.56.
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Analysis
by VulDB Data Team • 06/03/2024
This vulnerability represents a critical stack-based buffer overflow flaw in NETGEAR networking equipment that exposes multiple device models to remote exploitation without requiring authentication. The vulnerability affects a range of wireless routers and access points including the EX2700, R7800, WN2000RPTv3, WN3000RPv3, and WN3100RPv2 models across specific firmware versions. The flaw occurs when the device processes incoming network packets that contain overly long data sequences, causing the program to write beyond the allocated buffer space on the stack. This type of vulnerability falls under CWE-121 which specifically addresses stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations.
The operational impact of this vulnerability extends beyond simple denial of service scenarios as it creates potential pathways for remote code execution and complete system compromise. An unauthenticated attacker can exploit this flaw by sending specially crafted network packets to the affected devices, potentially gaining root access to the router's operating system. The vulnerability's severity is compounded by the fact that it affects multiple device generations and firmware versions, creating widespread exposure across NETGEAR's product portfolio. Attackers could leverage this vulnerability to establish persistent backdoors, redirect traffic through malicious proxies, or use the compromised devices as launching points for broader network attacks. This aligns with ATT&CK technique T1071.001 for application layer protocol usage and T1059.007 for command and scripting interpreter.
The technical exploitation requires understanding of the device's network stack implementation and memory management patterns. The buffer overflow occurs during packet processing when the device fails to properly validate the length of incoming data before copying it into fixed-size buffers. This allows attackers to overwrite return addresses, function pointers, and other critical stack variables that control program execution flow. The vulnerability's presence in multiple device models suggests a systemic flaw in the firmware development process, potentially indicating poor input validation practices and inadequate memory management controls. Organizations should prioritize immediate firmware updates to address this vulnerability, as the risk of exploitation increases with the availability of public proof-of-concept code. Network segmentation and monitoring for unusual traffic patterns can provide additional defense-in-depth measures while waiting for official patches to be deployed across affected networks.