CVE-2022-38638 in Casdoor
Summary
by MITRE • 09/10/2022
Casdoor v1.97.3 was discovered to contain an arbitrary file write vulnerability via the fullFilePath parameter at /api/upload-resource.
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Analysis
by VulDB Data Team • 10/15/2022
The vulnerability identified as CVE-2022-38638 affects Casdoor version 1.97.3 and represents a critical arbitrary file write vulnerability that can be exploited through the fullFilePath parameter within the /api/upload-resource endpoint. This flaw allows attackers to write files to arbitrary locations on the server filesystem, potentially leading to remote code execution or complete system compromise. The vulnerability stems from insufficient input validation and sanitization of file path parameters, creating a path traversal condition that enables malicious actors to bypass normal file upload restrictions and write malicious content to critical system directories.
The technical implementation of this vulnerability involves the manipulation of the fullFilePath parameter to specify arbitrary destinations for uploaded files. When a user submits a file through the upload-resource API endpoint, the application processes the fullFilePath parameter without adequate validation to ensure that the target path remains within the intended upload directory. This design flaw enables attackers to craft malicious requests that can write files to system directories such as /etc/, /var/www/, or other critical locations where the web application has write permissions. The vulnerability is particularly dangerous because it can be exploited without authentication in many configurations, making it accessible to any attacker who can reach the vulnerable endpoint.
From an operational impact perspective, this vulnerability poses severe risks to organizations using Casdoor for authentication and authorization services. Successful exploitation could result in complete system compromise, allowing attackers to install backdoors, modify critical system files, or establish persistent access to the infrastructure. The arbitrary file write capability also enables attackers to upload malicious scripts or binaries that can be executed by the web server, potentially leading to privilege escalation attacks. Security teams face significant challenges in detecting such attacks as they may appear as legitimate file uploads in system logs, making them difficult to distinguish from normal operational activities.
The vulnerability aligns with CWE-22 Path Traversal and CWE-73 Path Traversal, both of which address improper input validation that allows attackers to manipulate file paths and access unauthorized locations within the filesystem. From an ATT&CK framework perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1566 Phishing, as attackers can leverage the arbitrary file write capability to deploy malicious payloads and establish initial access. Organizations should implement immediate mitigations including input validation of all file path parameters, implementing proper access controls for upload directories, and restricting write permissions to the web application user account. Additionally, network segmentation and monitoring of the upload API endpoint can help detect and prevent exploitation attempts.
The remediation strategy should involve upgrading to Casdoor version 1.97.4 or later, which includes proper input validation and sanitization of file paths. Organizations should also implement proper file upload restrictions, including validating file extensions, implementing content type checks, and ensuring that uploaded files are stored in restricted directories with minimal write permissions. Regular security auditing of API endpoints and implementing web application firewalls can provide additional layers of protection against similar vulnerabilities. The incident highlights the importance of secure coding practices in file handling operations and demonstrates how seemingly simple functionality can become a critical security risk when proper input validation is absent.