Show file extensions in Windows (11 and 10)
Windows hides known file extensions by default, which helps malware disguise itself. Turn extensions on once and leave them on.
Windows 11
- Open File Explorer (
Win + E). - Click View in the toolbar.
- Open View > File name extensions and tick the box.
Now a file called document.pdf.exe no longer appears as document.pdf.
Windows 10
- Open File Explorer.
- Click the View tab.
- Check File name extensions on the right.
Why it matters
- Hiding known extensions is one of the single most exploited defaults on Windows. Malware distributors rely on it.
- Double-checking backups or email attachments is impossible when you cannot see the real extension.
- In managed environments, enforce this via Group Policy so every user has extensions visible.