Yes, computer hackers get together for conventions, just like entomologists & ethnologists & philatelists & paleontologists.At a recent computer hacker's convention in Las Vegas, a wide variety of voting equipment was easily hacked. Push-button machines & touch-screen machines & the scanners (OCR or Op-Scan) that read paper ballots. Each one required only seconds to insert malware. Most were available by wireless or bluetooth, so the hacker didn't even have to touch the machine.
The problems are endemic. The manufacturers themselves cannot be trusted. The machines are hackable by design because the people who are in charge of running our elections are not above wanting to affect the outcome.
Return to hand-counted paper ballots is the obvious and straightforward solution. It's much harder to steal elections when there are no computers involved.