Is this file safe?

Straight answers for the file types people worry about: what each one can actually do, what it cannot, how a hostile one looks, and what to check before opening it.

Every answer starts the same way: confirm the file is what its name claims. The detector does that from the bytes, in your browser.

• Can a PDF contain a virus?

  Yes. PDF is a programmable format, and malicious PDFs have been a routine attack vector for twenty years; a modern, updated reader makes exploitation rare, but the file type itself is not safe by nature.

• Is an EXE file safe to open?

  An .exe is a program. Opening it runs whatever the author wrote with your user's permissions, so the only question that matters is whether you trust where it came from.

• Can a Word document contain a virus?

  A .docx does not support embedded VBA macros, but it can still lead to code execution through embedded objects, remote templates, or parser exploits. Word documents remain one of the most common malware carriers; treat unexpected Office attachments as untrusted.

• Is it safe to open a ZIP file?

  Opening a ZIP to look inside is safe; the archive itself does nothing. The danger is what is inside, and ZIP is the standard wrapper for delivering malware because it hides the real file type from email filters and from you.

• Can an SVG file be dangerous?

  Yes: an SVG is XML that can contain JavaScript, so opened directly in a browser it behaves like a web page. Browsers disable scripting when SVGs are loaded as images, but that does not make an uploaded SVG safe to open directly.

• Is an HTML attachment safe to open?

  An HTML file is a web page, and opening it runs any JavaScript it contains on your machine. HTML attachments are one of the most common phishing vehicles precisely because the browser does exactly what the file says.

• Can a JPEG image contain a virus?

  Practically no. A JPEG is pixel data and the image viewers that decode it are heavily tested; real exploits through image files are rare and short-lived. The common trick is a file named .jpg that is not a JPEG at all.

• Are LNK shortcut files dangerous?

  Yes, more than they look. A Windows shortcut can run any command with arguments, show any icon, and hide its target in a field most people never see. Since Office began blocking macros, .lnk files have become a favourite malware delivery method.