CVE-2024-24550: Bludit - Remote Code Execution (RCE) through File API

Remedy

1. Remove file upload API: As the API POST request for uploading files is not documented, it can be assumed that it is a feature not actually needed by Bludit users. This is substantiated by the fact that users also cannot upload arbitrary files with the web application (AJAX). 2. Use an allowlist: If the first suggestion is not feasible as it is an actively used feature of Bludit users, it is advised to restrict the possible upload file formats with an allowlist. Before storing the uploaded files in the intended directory, their file extension and mime type should be checked. 3. Restrict upload storage: Users should only be allowed to store a certain amount of data on the file share (e.g. 10MB). 4. If uploaded files should not be downloadable by everyone: Ensure that the temporary file directory is relocated outside of the web root to prevent unauthorized access. 5. If uploaded files should be downloadable: Disable PHP in upload folder, e.g. with the following configuration in nginx: ``` location /upload_folder {     # Disable PHP execution     location ~ \.php$ {         deny all;     }     # Allow other file types     location /upload_folder/ {         # Additional configurations for other file types if necessary     } } ```