What kind of drone might be able to fly so high that it "operate(s) outside national boundaries"?
Normally, controlled airspace ends at 60,000 ft (Flight Level 600). Airplanes flying higher than that would be operating outside of controlled airspace. Currently, there is no internationally agreed definition where national airspace ends. However, aircraft flying higher than 60,000 ft (18,288 m) could claim to fly outside of national boundaries.

There are several airplane designs capable of flying above that height:


The venerable Lockheed U-2 should be first on this list, even though it is sometimes loaded with sensors such that it can climb above FL600 only at the end of its mission.
Next would be the Lockheed SR-71, but none are still flying.
Both the Myasishchev M-17 and the larger M-55 also qualify.
But most likely the photo has been taken by a RQ-4 Global Hawk which officially flies up to 60.000 ft high.


Even though those designs fly at a height where 98% of the atmosphere is below them, they are still firmly flying within it, technically or otherwise.

There are several more which can fly much higher, but those are research aircraft which do not take photo trips into Iran. Of course, there can still be a classified design of which we don't know yet.

EDIT: Now it is reported that satellite tracking has identified the source of the photo as USA 224, a spy satellite launched in 2011. Using the shadows in the picture as a sun dial, the exact time could be determined and the corresponding satellite was traced down by amateur satellite hunters.