When you bring thousands of hackers together, it is likely to be a recipe for terror.

As two major hacking events, Black Hat and DEF CON, commence this week in Las Vegas, hackers will unveil some new security flaws in our everyday technology, even internal technology. Pacemakers, specifically. 

“Psh,” you may be thinking, “There’s no way that they can do that.” Before he passed away last week, infamous hacker Barnaby Jack was scheduled to give a speech about security fallacies in exactly that technology.

See below for some of the frightening hacks participants will be doing at the conventions.