CVE-2022-31545 in ModelConverter
Summary
by MITRE • 07/11/2022
The ml-inory/ModelConverter repository through 2021-04-26 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-2022-31545 resides within the ml-inory/ModelConverter repository, a tool designed for converting machine learning models between different formats. This repository, as of its final release on April 26, 2021, contained a critical security flaw that stems from improper handling of file paths in web applications. The issue manifests specifically through the unsafe usage of the Flask send_file function, which is a core component in web application frameworks that facilitates serving files to users. When developers utilize Flask's send_file function without proper input validation or sanitization, they create opportunities for attackers to manipulate file access requests.
The technical flaw represents a classic path traversal vulnerability that operates through the Flask web framework's file serving mechanism. The send_file function, when invoked with unsanitized user input, allows attackers to specify absolute file paths on the server filesystem rather than restricting access to a designated directory. This occurs because the application fails to properly validate or sanitize the file path parameter before passing it to the send_file function. An attacker can exploit this by crafting malicious requests that include directory traversal sequences such as ../ or absolute paths that bypass intended access controls. The vulnerability maps directly to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it could potentially allow attackers to access sensitive files on the server that were not intended for public access. In the context of a model conversion tool, this could mean exposure of configuration files, authentication credentials, source code, or other sensitive data stored on the same server. Attackers could leverage this vulnerability to escalate their privileges and potentially gain access to the underlying system, depending on how the application is deployed and what files are accessible through the vulnerable endpoint. The attack surface is particularly concerning for applications running on shared hosting environments or systems where the web application has elevated privileges. This vulnerability aligns with ATT&CK technique T1083, which covers directory and file searches, and could contribute to broader attack chains involving credential access and system compromise.
Mitigation strategies for CVE-2022-31545 require immediate attention through proper input validation and secure coding practices. The primary fix involves sanitizing all user-provided file paths before passing them to the send_file function, ensuring that only relative paths within a designated safe directory are accepted. Implementing proper path validation techniques such as canonicalizing paths, using secure file access libraries, and restricting file access to predefined directories can effectively prevent this type of attack. Organizations should also consider implementing additional security measures including web application firewalls, input validation at multiple layers, and regular security code reviews. The fix should include proper error handling to prevent information leakage through error messages that might reveal system paths or file structures. Given the nature of the vulnerability, it is crucial to conduct thorough security testing including penetration testing and static code analysis to identify similar issues in other parts of the application or related components.