CVE-2022-31542 in mdweb
Summary
by MITRE • 07/11/2022
The mandoku/mdweb repository through 2015-05-07 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.
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Analysis
by VulDB Data Team • 07/21/2022
The vulnerability identified as CVE-2022-31542 resides within the mandoku/mdweb repository, a web application built using the Flask framework. This repository, which was last updated on May 7, 2015, contains a critical security flaw that enables attackers to perform absolute path traversal attacks. The issue stems from the improper usage of Flask's send_file function, which is designed to serve files from the filesystem to HTTP clients. When developers utilize this function without proper input validation or sanitization, they create an opportunity for malicious users to access files outside the intended directory structure. The vulnerability represents a classic case of insecure file handling that can lead to unauthorized data access and potential system compromise.
The technical flaw manifests when the application accepts user-provided file paths or identifiers that are directly passed to Flask's send_file function without adequate sanitization. This unsafe practice allows attackers to manipulate the file path parameter to traverse the filesystem hierarchy using techniques such as directory traversal sequences like ../ or ..\.. This vulnerability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. The Flask framework's send_file function is intended to securely serve files, but when combined with unsanitized user input, it becomes a vector for attackers to access sensitive files that should remain protected. The vulnerability affects any version of the repository up to and including the May 7, 2015 release, indicating that this security flaw existed for several years without detection or remediation.
The operational impact of this vulnerability extends beyond simple unauthorized file access. An attacker who successfully exploits this flaw can potentially read configuration files, source code, database files, or other sensitive system information that should not be publicly accessible. This could lead to exposure of database credentials, application secrets, or other confidential data that could be used for further attacks. The vulnerability also enables potential denial of service conditions if attackers can access critical system files or cause the application to consume excessive resources. From an attacker's perspective, this vulnerability fits within the attack pattern described by ATT&CK technique T1083, which involves discovering system files and directories. The impact is particularly severe because the repository appears to be a legacy application that may contain outdated security practices, making it more susceptible to additional exploitation vectors. The long window of exposure since the last update suggests that organizations relying on this codebase may have been unknowingly vulnerable for years.
Mitigation strategies for this vulnerability require immediate attention to the application's file serving mechanisms. The primary remediation involves implementing proper input validation and sanitization for all user-provided file paths before they are passed to Flask's send_file function. This includes using whitelisting approaches where only predetermined, safe file paths are allowed, or implementing strict path validation that prevents directory traversal sequences from being processed. Organizations should also consider using Flask's built-in security features such as the use of os.path.join() with proper path validation, or implementing a dedicated file serving layer that enforces strict access controls. Additionally, implementing proper access controls and authentication mechanisms can limit the scope of potential damage even if path traversal vulnerabilities exist. The remediation should follow security best practices outlined in OWASP Top Ten and NIST guidelines for secure coding practices, particularly focusing on input validation and secure file handling. Regular security audits and code reviews should be implemented to identify similar vulnerabilities in other parts of the application or related systems, as this type of flaw often indicates broader security weaknesses in the codebase that require comprehensive remediation.