[dwd]

Acrobat Reader lets you do a lot of potentially bad things with ActiveScript in a PDF once the user allows it.

I worked on a PDF form that was distributed widely within a Gov department. It would be routinely saved locally and emailed half completed up the managerial chain for sign-off on the request.

It had a lot of dynamic fields so you had to allow it to run macros.

The first thing it did was check the version of the just opened form and replace it with the latest PDF from the department's server.

It also had save/resume functionality which would only work in Acrobat Reader at the time.

Edit: Shout out to Inkscape which I find is a handy replacement for Illustrator and doing minor fixes to PDFs.