Sadly, far too often we hear about hackers getting punished for their exploits—even when the hack doesn’t really damage anyone. (RIP Aaron Swartz.)

Today, however, two people are being rewarded for a fun, harmless hack. After taking over a prominent electronic billboard in Belgrade, installing Space Invaders on it, and playing it via their iPhones for 20 minutes, two Serbian students were rewarded by the billboard's owner with two iPad mini 4Gs.

“This has never happened before, but we appreciate the fact that these guys have, in a charming way, pointed us to this huge problem,” Slobodan Petrovic, the manager of the billboard ad company, DPC, told Serbian news site Kurir on Wednesday (Google Translate). “Now it is clearer than ever that we need to protect ourselves better. In more developed countries, these actions are unthinkable because of severe sanctions.”

As TorrentFreak reported on March 10, Ivan Petrović, 21, and Filip Stanisavljević, 20, altered the billboard in one of Belgrade’s most prominent plazas, ending their demonstration with the message “Hacked4Fun” and a picture of The Pirate Bay logo with the Ghandi quote that the Swedish trio likes to use: “First they ignore you, then they laugh at you, then they fight you, then you win.”

As seen in a video Petrović and Stanisavljević uploaded to YouTube, the assembled crowd seemed mystified but pleasantly surprised. Ars has tried contacting the pair via YouTube but has not heard back yet.

In the notes, the pair claim they are not "hackers," by which we assume they mean the contemporary, negative sense of the word—not its original meaning.

We are not members of "Anonymous" and are in no way affiliated with them. We are not members of any hacker organization or group and this clip proves that in a way - we do not want to stay anonymous in any way. We are not hackers nor do we participate in any form of hacking. We are two computer science students who did this for research purposes only, to demonstrate the lack of security in IT systems in general. We wanted to demonstrate how companies sometimes pay very little attention to security—it had nothing to do with this specific company or even billboard companies, but rather any company that uses any form of technology that can be targeted by this kind of "attack". We chose the billboard simply because we believed it is the strongest way to prove our point. No damage was done by us—the billboard was inactive for a total of 22 minutes and normal function was restored as soon as our demonstration was over. The billboard owner was contacted about the weaknesses in the system with all the necessary information to fix the problem.

"We think of ourselves as white-hat hackers"

UPDATE 12:20pm CT: Ivan Petrović contacted Ars via Skype from his new iPad mini—over WiFi—he lamented the fact that LTE has unfortunately not yet come to Serbia.

"We thought this was funny and can help people understand that IT systems are not so well protected," he said. "We thought we would like to demonstrate a game. The first idea started because we look at the screen [everyday, from our university across the street.] We were just thinking of it a year ago: it would be cool to play a game on that screen."

When Ars asked him about their message, that they are not hackers in the pejorative sense of the word, he agreed.

"Serbia is a small country," he said. "We don't have big infrastructure. [Most Serbians] don't understand the meaning of the word 'hacker.' We are trying to get people to understand. We think of ourselves as white-hat hackers, but you can't express that to people here, they don't understand that."

After the hack, the pair of computer science students—who have now become known within Serbia as the "billboard hackers"—alerted the company with a detailed description of the security flaw, and how to fix it. But nevertheless, as the Serbian media started to dub them as "bad hackers," they seriously worried that they might have to flee the country.

"One thing we learned is that this kind of public hacks are not good for us," he added. "We were so stressed. Especially me, I was feeling bad when all the bad news started. At first, we were portrayed as some kind of 'Anonymous' group. We were surprised—we showed our faces [in the video], we didn't want to hide. The first night we were thinking about running out of the country. We wanted to go to Montenegro—but we were not sure, but we were talking about that."

By the time DPC reached out to them to thank them for exposing the flaw, Petrović said he was very surprised.

"We were doing this for fun, [but] we expected we would be punished a little," he said. "When they called us to give us the present we thought it was really really cool. We were relived when they called us [and wanted to give us the iPads.]"

And why the shout-out to the Pirate Bay?

"We are fans of the Pirate Bay," he said. "Especially after watching the movie that was released recently. That's why we want to show some kind of support."

So what's next for the young white-hat hacker?

"I would really like to work in system security and low-level programming—I'm not some GUI guy."