So, with cookies.
- password strength checkers
- JSON, YAML, EDN, whatever prettiers
- checksum generators
- Base64 (en|de)coders
- etc.
I hadn't heard of responsible disclosure at the time. ¯\_(ツ)_/¯
Over a period of a few months I got quite a decent result from people who'd just happened to visit my website.
Not quite as malicious as your story but equally nefarious.
You could try:
http://getposted.io/post?action=https://news.ycombinator.com...
But you shouldn't. That use case is specifically why I bring up the privacy issues surrounding using it.
This doesn't enable anything that wasn't already possible; it would be trivial for a bad actor to put up a redirector like this, after all. Still, at least when they do that, it's something they did and you have no responsibility.
I don't even know exactly what it is you don't want to be part of. It's just the possible range of URLs you probably will eventually start seeing come through will cross some sort of line for almost any given individual.
Says it all.
data:text/html,<form method=post action=URL>params...<input type=submit></form>
I'd recommend some examples (maybe some POST requests to third party services and what they return).
I mean that's essentially what it's doing — why bother using a third party service at all?