CVE-2019-17187 in HG2201T
Summary
by MITRE
/var/WEB-GUI/cgi-bin/downloadfile.cgi on FiberHome HG2201T 1.00.M5007_JS_201804 devices allows pre-authentication Directory Traversal for reading arbitrary files.
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Analysis
by VulDB Data Team • 01/05/2024
The vulnerability identified as CVE-2019-17187 represents a critical pre-authentication directory traversal flaw in the FiberHome HG2201T 1.00.M5007_JS_201804 device firmware. This vulnerability exists within the web-based graphical user interface component located at /var/WEB-GUI/cgi-bin/downloadfile.cgi, which processes file download requests without proper input validation or access control mechanisms. The flaw allows unauthenticated attackers to traverse the directory structure and access arbitrary files on the device filesystem, potentially exposing sensitive system information, configuration data, and credentials.
This directory traversal vulnerability falls under the CWE-22 category, specifically classified as "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')", which is a well-documented weakness in software systems where input validation fails to properly restrict file access to authorized directories. The vulnerability enables attackers to bypass authentication requirements entirely, as the flaw exists in a pre-authentication state where no credentials are required to exploit the vulnerability. The attack vector involves manipulating the filename parameter in the downloadfile.cgi script to navigate through the filesystem using directory traversal sequences such as ../ or ../../, allowing access to sensitive files outside the intended download directory.
The operational impact of this vulnerability is severe and multifaceted, potentially exposing critical system information including but not limited to administrative credentials, configuration files, system logs, and other sensitive data that could be used for further exploitation. Attackers could leverage this vulnerability to gain unauthorized access to the device's internal filesystem, potentially leading to complete device compromise, persistent backdoor access, or the ability to modify device configuration files. The vulnerability affects the device's web management interface, which is typically accessible from the network, making it exploitable from remote locations without requiring physical access or prior authentication credentials.
From a threat modeling perspective, this vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1213 (Data from Information Repositories), as it enables unauthorized discovery and extraction of sensitive data from the target system. The vulnerability also represents a significant risk to network security posture, as it provides an unauthenticated attack surface that could be exploited by malicious actors to gain insights into the device configuration and potentially escalate privileges. The impact extends beyond simple information disclosure, as access to configuration files might reveal network settings, user credentials, or other sensitive data that could be used for lateral movement within the network or for additional attacks against connected systems. Organizations should implement immediate mitigations including firmware updates from the vendor, network segmentation to limit access to the device, and monitoring for suspicious file access patterns in the device logs.
The vulnerability demonstrates the critical importance of proper input validation and access control implementation in web applications, particularly in embedded systems and network devices where authentication bypasses can lead to complete system compromise. Security practitioners should consider this vulnerability as part of broader network security assessments, ensuring that all network-connected devices undergo regular security scanning and firmware updates to address known vulnerabilities. The presence of such a flaw in a device's web interface highlights the need for comprehensive security testing during device development and deployment phases to prevent similar issues from being present in production environments.