A common piece of advice for staying safe online is to avoid opening attachments from unknown senders or anything that looks suspicious. It’s good advice! PDFs and Office documents can include scripts or macros, and in some cases, they can even be designed to take advantage of vulnerabilities and run code on your computer.
The challenge is that in real life, it’s not always obvious what’s safe and what’s not. Unless an email is clearly spam, you’re often left guessing. And sometimes you just need to see what’s in the document. So how do you check it without taking a risk?
Enter Dangerzone, an open source app created by the nonprofit Freedom of the Press Foundation. It’s a free, open source app originally built for journalists who regularly deal with files from unknown or untrusted sources.
Dangerzone doesn’t try to determine if a document is safe. Instead, it takes a different approach. When you drop a file into the app, it creates a clean PDF version that contains only the visual content of the original. No scripts, no macros, just a pixel-based copy. Think of it like making a photocopy of the document.
Behind the scenes, there’s quite a bit going on to make that happen safely. Dangerzone opens the file inside a locked-down environment that keeps it completely isolated from your Mac. It then uses open source tools to convert the document into a PDF, break it into pages, and rebuild each page as a simple image made of pixels. Once that process is complete, it saves a clean, usable PDF and keeps the original file separate.
You can process one file or a batch at a time, and each run starts fresh to keep things contained and predictable.
Here are the types of documents Dangerzone can convert into safe PDFs:
- PDF (.pdf)
- Microsoft Word (.docx, .doc)
- Microsoft Excel (.xlsx, .xls)
- Microsoft PowerPoint (.pptx, .ppt)
- ODF Text (.odt)
- ODF Spreadsheet (.ods)
- ODF Presentation (.odp)
- ODF Graphics (.odg)
- EPUB (.epub)
- JPEG (.jpg, .jpeg)
- GIF (.gif)
- PNG (.png)
- SVG (.svg)
- TIFF (.tif, .tiff)
- Other image formats (.bmp, .pnm, .pbm, .ppm)
You don’t need to use Dangerzone for every attachment. If a document comes from someone you know and it makes sense in context, there’s no need to add extra steps. But if you ever get a file that makes you pause and wonder why it was sent, running it through Dangerzone is a simple way to take a closer look without putting your computer at risk.
(Featured image by iStock.com/shironosov)
