CVE-2020-18331 in P21-C-CN
Summary
by MITRE • 01/26/2023
Directory traversal vulnerability in ChinaMobile PLC Wireless Router model GPN2.4P21-C-CN running the firmware version W2000EN-01(hardware platform Gpn2.4P21-C_WIFI-V0.05), via the getpage parameter to /cgi-bin/webproc.
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Analysis
by VulDB Data Team • 04/01/2025
This directory traversal vulnerability exists in the ChinaMobile PLC Wireless Router model GPN2.4P21-C-CN which operates on firmware version W2000EN-01 running on the Gpn2.4P21-C_WIFI-V0.05 hardware platform. The vulnerability specifically affects the web management interface accessible through the /cgi-bin/webproc endpoint where the getpage parameter is susceptible to manipulation. This flaw allows an attacker to traverse directories on the affected device and access sensitive files that should normally be restricted. The vulnerability is classified as CWE-22 according to the Common Weakness Enumeration catalog, which details improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal.
The technical exploitation of this vulnerability occurs when an attacker sends a crafted request to the /cgi-bin/webproc endpoint with a malicious getpage parameter value that includes directory traversal sequences such as ../ or ..\.. The router fails to properly validate or sanitize the input parameter, allowing the attacker to access files outside the intended web root directory. This could potentially expose sensitive system information, configuration files, credentials, or other confidential data stored on the device. The vulnerability represents a critical security risk as it enables unauthorized access to the device's internal file system without requiring authentication, making it particularly dangerous in networked environments.
The operational impact of this vulnerability is severe as it provides attackers with the ability to read arbitrary files from the router's file system, potentially leading to complete system compromise. An attacker could extract configuration files that might contain administrative credentials, network settings, or other sensitive information. The vulnerability affects the device's web interface security model, which should normally restrict access to system files and configuration data. This issue represents a failure in input validation and access control mechanisms within the web application layer of the router's firmware. The attack surface is particularly concerning given that the affected device is a wireless router, which typically serves as a gateway for network access and often contains sensitive network configuration data.
Mitigation strategies for this vulnerability should include immediate firmware updates from the vendor to address the directory traversal flaw. Network administrators should implement network segmentation and access controls to limit exposure of the affected devices to untrusted networks. The principle of least privilege should be applied by restricting access to the web management interface to trusted IP addresses only. Additionally, monitoring network traffic for suspicious requests to the /cgi-bin/webproc endpoint can help detect exploitation attempts. Security controls should be aligned with the MITRE ATT&CK framework, specifically targeting T1210 - Exploitation of Remote Services and T1566 - Phishing, as attackers may use this vulnerability to gain initial access to networks. Organizations should also consider implementing web application firewalls to filter malicious requests targeting the vulnerable parameter. The vulnerability highlights the importance of secure coding practices and input validation in embedded systems, particularly in network infrastructure devices where the consequences of exploitation can be extensive.