CVE-2022-31548 in homepage
Summary
by MITRE • 07/11/2022
The nrlakin/homepage repository through 2017-03-06 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-2022-31548 resides within the nrlakin/homepage repository, which was last updated on March 6, 2017, and represents a critical security flaw in web application architecture. This repository appears to have been a simple homepage or static site generator that utilized the Flask web framework for serving content. The vulnerability manifests through an unsafe implementation of the Flask send_file function, which is a core component for serving files from a Flask application. When developers use send_file without proper input validation or sanitization, they create an attack surface where malicious actors can exploit the function to access arbitrary files on the server filesystem.
The technical flaw stems from the improper handling of user-supplied input that is directly passed to the Flask send_file function. This function is designed to securely serve files from a specified path, but when it receives an absolute path or a path containing directory traversal sequences such as ../, it can be manipulated to access files outside of the intended directory structure. The vulnerability represents a classic path traversal attack vector where the attacker can manipulate the file path parameter to navigate through the filesystem hierarchy and potentially access sensitive files including configuration files, database credentials, source code, or system files that should remain protected. This issue directly maps to CWE-22, which defines Path Traversal vulnerabilities as a weakness where an attacker can access files and directories that are stored outside the intended directory.
The operational impact of this vulnerability is significant as it can enable attackers to extract sensitive information from the server environment. An attacker who exploits this vulnerability could gain access to database connection strings, API keys, application configuration files, and potentially even source code repositories. The exposure of such information could lead to further exploitation opportunities including privilege escalation, data breaches, or complete system compromise. The vulnerability is particularly dangerous because it allows for absolute path traversal, meaning attackers can navigate to any location on the filesystem rather than being limited to a specific directory. This capability aligns with ATT&CK technique T1083, which describes the discovery of files and directories, and can be leveraged as part of a broader attack chain to escalate privileges or extract additional sensitive data.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization for all user-supplied parameters that are used in file operations. The Flask application should never directly pass user input to send_file without thorough validation and sanitization. Implementing a whitelist approach where only pre-approved file paths or names are allowed can effectively prevent directory traversal attacks. Additionally, developers should utilize Flask's built-in security features such as setting proper file access controls and implementing proper directory restrictions. The application should run with minimal privileges and avoid using absolute paths when possible. Regular security audits and code reviews should be conducted to identify similar patterns in other parts of the application. The vulnerability highlights the importance of following secure coding practices and demonstrates how seemingly simple functions can become dangerous when not properly secured against malicious input manipulation.