CVE-2022-31511 in equanimity
Summary
by MITRE • 07/11/2022
The AFDudley/equanimity repository through 2014-04-23 on GitHub allows absolute path traversal because the Flask send_file function is used unsafely.
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Analysis
by VulDB Data Team • 07/20/2022
The vulnerability identified as CVE-2022-31511 resides within the AFDudley/equanimity repository, a project hosted on GitHub and active through April 23, 2014. This repository implements a web application using the Flask framework, which introduces a critical security flaw through improper handling of file operations. The vulnerability stems from the unsafe usage of Flask's send_file function, which is designed to serve files from the filesystem to HTTP clients. When developers utilize send_file without proper input validation or sanitization, they create an environment where malicious users can manipulate file paths to access arbitrary files on the server's filesystem. This particular implementation fails to adequately restrict user-provided file paths, allowing attackers to traverse the filesystem beyond intended boundaries and potentially access sensitive files such as configuration data, source code, or system credentials. The vulnerability represents a classic path traversal attack vector that violates fundamental security principles of access control and input validation.
The technical flaw manifests when the Flask application processes user requests that specify file paths for retrieval through the send_file function. In a properly secured implementation, the application should validate that requested file paths are within a designated safe directory and that user input does not contain sequences such as '../' or absolute path indicators like '/'. However, in this vulnerable implementation, the application directly passes user-provided parameters to send_file without adequate sanitization, creating a condition where an attacker can construct malicious paths that bypass normal filesystem access controls. This unsafe usage pattern aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal vulnerabilities. The flaw essentially allows an attacker to specify absolute paths or manipulate relative paths to access files outside the intended application directory structure, potentially leading to complete system compromise or data exfiltration.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the capability to access arbitrary files on the server. An attacker could potentially retrieve sensitive configuration files containing database credentials, application secrets, or other confidential information. The vulnerability also enables further exploitation techniques such as remote code execution if the attacker can access system files or configuration that allows for code injection. The risk is particularly elevated in web applications where the server process has elevated privileges, as attackers could access files that would otherwise be protected by filesystem permissions. This vulnerability can be exploited through simple HTTP requests that manipulate the file path parameter, making it a low-effort, high-impact security flaw that could remain undetected for extended periods due to its subtle nature and the common practice of using send_file without proper validation.
Mitigation strategies for this vulnerability must focus on implementing proper input validation and sanitization of file paths before they are processed by Flask's send_file function. The recommended approach involves establishing a whitelist of allowed files or directories that can be accessed through the application, ensuring that all user-provided paths are validated against this restricted set. Additionally, developers should implement absolute path resolution and directory traversal checks to prevent manipulation of relative paths. The application should enforce strict access controls that limit file access to only necessary resources and implement proper error handling that does not reveal internal filesystem structure. Organizations should also consider implementing web application firewalls and input validation mechanisms to detect and block suspicious path traversal attempts. This vulnerability demonstrates the critical importance of following secure coding practices and adhering to the principle of least privilege when handling file operations in web applications. The remediation process should include comprehensive code review to identify all instances where send_file or similar functions are used without proper validation, and developers should be trained on secure file handling practices to prevent similar issues in future implementations.