Slot Machine Hacking

Posted by: Rea Maor In: Security and Prevention - Sunday, July 29th, 2007

Slot machines, aka fruit machines and one-armed bandits, have been getting a little press in the news amongst the geek community lately. A recent case of a slot machine with faulty software has raised the question of whether a person playing a machine is guilty of a crime if they knowingly exploit a defect.

Doubly, there is a recent report by a Stanford student on the psychology and design of slot machines. A good exercise for the budding hacker is to reverse-engineer a slot or other casino game on their home computer, using whatever programming language they’re handy with. It’s good exercise both for programming and figuring math probability – one of the weakest areas the public has in math. And of course, it will help teach you how slots work.

A little-known fact is that slot machines can be hacked in much the same way that regular computers can be hacked – and one famous guy actually did it! That would be one Ronald Dale Harris, whom you might call the Kevin Mitnick of slot machines. There’s been a few documentaries about his story running around on cable TV.

Harris worked for the Nevada Gaming Control Board in the early 1990s. It was his job to find flaws in the software that runs computerized casino games. What he ended up doing was write the program which casino employees would take around on a portable unit to plug into slot machines and test to make sure the software running on them was correct. Except that he wrote a little exploit and slipped it into the code!

The exploit worked in much the same way as a root-kit for the computer: it installed a patch in the slot machine which would trigger a jackpot payout upon recognition of a certain code. The “code” to trigger the payout would be a sequence of coins – for example, one coin, then two, then three, then one, etc. The exact sequence is not known.

But as a Gaming Commission employee, he was forbidden by law from even playing the games, so he had to hire an accomplice. Together, they collected thousands of dollars, but after a couple years of this, Harris’ reliance on an accomplice would be his downfall.

Harris decided to try playing for bigger stakes, and so he reverse-engineered the random number generator used in Keno games. Using a radio communication, Harris had his friend play Keno on the floor, while he watched the results on TV from his motel room and typed the numbers into a program on his laptop. The program eventually recognized the number sequence and correctly predicted the next draw – since the random numbers were actually pseudo-random numbers generated from a mathematical algorithm. But Harris’ accomplice blew it by fumbling his ID when he went to collect the winnings, showing a fake ID at the counter when he’d used his real ID to check in. The duo was busted!

Harris only served two years in prison for his crimes, and today works in publishing. He is of course barred from ever showing his face in a casino again. As for the clean-up: today’s casinos use a much stronger method of generating random numbers, and the compromised slot games were patched. But will we ever know exactly how many machines were hit, whether every one was accounted for, or what other exploits Harris rigged during his career?

This article was written by Casino Filter, the only free casino portal that gives you the best results.

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5 Responses to “Slot Machine Hacking”



    Log onto Youtube and type in the word BEARDEBEAR to view a promotional video film on how slot machines were manufactered in 1978 to cool music. Can you spot the two mistakes in the film.

  2. Says:


    Majority of slot machines we’ve encountered are still running old code / software. One example is the “snooker” game with the little circle mouse device. I’ve seen it rebooting several times, perhaps Harris’s ghost still lives on!!

  3. john Says:

    would like codes for b13s rainbow riches english 500s can we disscuss further or other things that actually work

  4. john Says:

    i have also heard of laminating money and using foil and bit of wire for note inserting how does that work

  5. Darkmatter Says:

    The machines he compromised have long since been cycled out (slot program life is about 5 years).

    Most manufacturers have updated their random number generators since about ’97. Most use a type of ‘bucket’ or ‘bubble’ algorithm to generate their values, for which there would be no way to compromise using a method similar to Harris’.

    If that wasn’t bad enough, they all operate on a closed system. There is no outside access to any of the machines or networks they operate on. You have to be a regulator or casino operator to touch it, and even then the production software cannot be manipulated in any way without setting off alarms.

    In short, Harris was a genius in his design, but a buffoon in his execution. He got greedy and he paid the appropriate price.

    Now, should someone get inventive with RF emitters… Just be patient when you do.

    PS – john, I have such code, but you couldn’t use it to accomplish anything. Even with the actual random number generator, unless you know what the initial seed was, you’re dead in the water. And knowing that the jackpot would trigger in 10,000,000 plays won’t help you, either.

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