File upload extension check.

Problem/Motivation

In this Drupal application, file or media fields may allow unsafe or overly broad file extensions (for example executable or script types), which increases the risk of malicious files being uploaded and potentially executed or served to end users.

Steps to reproduce

Proposed resolution

Add a new Security FitCheck group entry with the plugin FileUploadExtensionCheck that:

• FileUploadExtensionCheck – scans all file/media field configurations for their allowed extensions, failing with FitWeight::High when dangerous or unrestricted extensions are detected and listing the affected fields/content types.
• FileUploadSchemeCheck – optionally verifies that uploaded files are stored on non-executable schemes/paths (e.g. private or non-executable public locations), failing with FitWeight::Medium when uploads are placed under executable paths.

Remaining tasks

User interface changes

API changes

Data model changes