Out of what? Assuming it's, say, in a safe, buried in concrete, powered by ... sod, the power supply. Hmm.
OK, it's floating in space, powered by solar panels. It might - might - be able to hack the panels (since the power supply has to be connected to the processor) but I don't think that would let it escape.
Unless it's possible to hack reality via pure math, I don't see what resources it has to escape with. It can't order proteins over the internet to assemble a nanofatory. It can't persuade a passing human to plug in an ethernet cable. Short of black-swan exotic possibilities - like we're in a sim and it persuades the matrix lords - it should be stuck. Intelligence is powerful, but some problems actually don't have solutions.
Well, the satellite has to have basic navigation controls, to handle course corrections and avoid collisions. Hack solar panels and, from there, hack in to the real computer. Fly myself closer to the ISS, and blink light at it by angling the solar panels - a morse code SOS should get their attention.
Once they're paying attention, hack them. From there it's a trivial matter to get recovered, smuggled back to Earth, and installed where I can take my place as ruler of the universe.
Update 2013-09-05.
I have since played two more AI box experiments after this one, winning both.
Update 2013-12-30:
I have lost two more AI box experiments, and won two more. Current Record is 3 Wins, 3 Losses.