What happens when an app becomes so popular it’s basically a public utility? For a school project, Shir Yadid and Meital Ben-Sinai, fourth-year students at Technion-Israel Institute of Technology, hacked the incredibly popular Waze GPS map, an Israeli-made smartphone app that provides directions and alerts drivers to traffic and accidents. The students created a virtual traffic jam to show how malicious hackers might create a real one. One of the ways that Waze learns about traffic problems is through reports from users. At its best, the app crowdsources road conditions from drivers, thus making everyone’s commute shorter. Waze was so popular that last summer Google bought it for $1 billion. Yadid and Ben-Sinai created and registered thousands of fake Waze users, using a program that impersonated smartphones.