CVE-2020-36973 in PDW File Browser
Summary
by MITRE • 01/28/2026
PDW File Browser 1.3 contains a remote code execution vulnerability that allows authenticated users to upload and rename webshell files to arbitrary web server locations. Attackers can upload a .txt webshell, rename it to .php, and move it to accessible directories using double-encoded path traversal techniques.
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Analysis
by VulDB Data Team • 01/29/2026
The vulnerability identified as CVE-2020-36973 affects PDW File Browser version 1.3, a web-based file management tool that provides users with the ability to interact with server file systems through a graphical interface. This authentication-based remote code execution flaw represents a critical security weakness that directly compromises the integrity and confidentiality of web applications relying on this component. The vulnerability stems from inadequate input validation and improper file handling mechanisms within the application's file upload and renaming functionalities, creating a pathway for malicious actors to execute arbitrary code on the target server.
The technical implementation of this vulnerability involves multiple attack vectors that exploit weaknesses in the application's path traversal and file manipulation capabilities. Specifically, authenticated users can leverage the file upload functionality to initially place a webshell payload in a temporary location, then utilize the rename feature to change the file extension from .txt to .php. The double-encoded path traversal technique employed by attackers allows them to bypass directory restrictions and move the renamed file to directories that are accessible through the web server, effectively creating a persistent backdoor. This technique relies on the server's insufficient validation of encoded path sequences, which can be exploited to navigate beyond intended directories and place malicious files in web-accessible locations.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, as it provides attackers with complete control over the affected web server. Once a webshell is successfully deployed and moved to a publicly accessible directory, attackers can execute arbitrary commands, escalate privileges, and maintain persistent access to the compromised system. This vulnerability directly violates the principle of least privilege and can lead to complete system compromise, data exfiltration, and potential lateral movement within network environments. The authenticated nature of the vulnerability means that attackers must first obtain valid credentials, but this requirement does not significantly limit the attack surface since many applications maintain weak authentication mechanisms or suffer from credential compromise through other vectors.
Security professionals should note that this vulnerability aligns with CWE-22 Path Traversal and CWE-434 Unrestricted Upload of File with Dangerous Type, both of which are commonly exploited in web application attacks. The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under T1105 Command and Scripting Interpreter and T1059 Command and Scripting Interpreter, where adversaries establish persistent access through web shells. The vulnerability demonstrates how seemingly benign file management features can become dangerous when proper input sanitization and access controls are not implemented. Organizations should implement comprehensive mitigations including strict file type validation, mandatory file extension checks, and proper directory access controls to prevent unauthorized file placement in web-accessible locations.
Mitigation strategies for CVE-2020-36973 should focus on immediate patching of the PDW File Browser component to version 1.4 or later, which addresses the identified vulnerabilities in file handling and path traversal protection. Additionally, administrators should implement strict file upload policies that prevent execution of files with dangerous extensions, enforce proper access controls on web server directories, and conduct regular security audits of file management functionalities. Network segmentation and monitoring solutions should be deployed to detect anomalous file upload activities and unauthorized file renames. The implementation of web application firewalls and input validation mechanisms can provide additional layers of protection against similar vulnerabilities in other applications. Organizations should also establish incident response procedures specifically designed to handle web shell deployments and ensure proper log retention for forensic analysis of potential compromise events.