CVE-2020-35362 in DEXT5Upload
Summary
by MITRE • 12/26/2020
DEXT5Upload 2.7.1262310 and earlier is affected by Directory Traversal in handler/dext5handler.jsp. This could allow remote files to be downloaded via a dext5CMD=downloadRequest action with traversal in the fileVirtualPath parameter (the attacker must provide the correct fileOrgName value).
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Analysis
by VulDB Data Team • 12/26/2020
This vulnerability exists within DEXT5Upload version 2.7.1262310 and earlier, specifically in the handler/dext5handler.jsp component where a directory traversal flaw has been identified. The issue manifests when processing download requests through the dext5CMD=downloadRequest action parameter, creating a pathway for unauthorized file access. The vulnerability requires an attacker to provide a valid fileOrgName value alongside malicious traversal sequences in the fileVirtualPath parameter to successfully exploit the weakness.
The technical implementation of this flaw stems from inadequate input validation and sanitization within the file path handling mechanism. When the application processes the fileVirtualPath parameter without proper restrictions on directory navigation sequences such as ../ or ..\, attackers can manipulate the request to access files outside the intended directory structure. This represents a classic directory traversal vulnerability that falls under the CWE-22 category, which specifically addresses improper limitation of a pathname to a restricted directory, also known as path traversal or directory traversal.
From an operational impact perspective, this vulnerability presents significant security risks to affected systems. An attacker could potentially access sensitive files including configuration data, user information, application source code, or other restricted resources that should not be accessible through the upload handler interface. The requirement for a valid fileOrgName value adds a layer of complexity but does not eliminate the threat, as obtaining this value may be achievable through reconnaissance or by leveraging other vulnerabilities within the same system. This weakness directly maps to several ATT&CK techniques including T1078 Valid Accounts for maintaining access and T1566 Phishing for initial compromise.
The attack surface expands when considering that this vulnerability affects a file upload handler component, which typically operates with elevated privileges or has access to restricted file systems. The combination of remote exploitation capability with directory traversal allows for potential information disclosure attacks that could lead to further system compromise. Organizations using affected versions should immediately implement mitigations including input validation, path normalization, and proper access controls to prevent unauthorized file access through this vector.
Recommended remediation strategies include implementing strict input validation on all file path parameters, applying proper path normalization techniques to eliminate traversal sequences, and ensuring that the application operates with minimal required privileges. Additionally, organizations should consider implementing web application firewalls and monitoring for suspicious traversal patterns in system logs. The vulnerability demonstrates the critical importance of secure coding practices and proper input validation in preventing directory traversal attacks that can lead to complete system compromise when not properly addressed through defense-in-depth strategies.