You have to hand it to NSO on this one. They might be evil but they sure aren't stupid.
They (loosely) created a virtual machine out of a (very) abstract vuln in the JBIG2 library to create their own logical Turing machine / computer that they then built their own simple architecture for...and then could allow for the computation of any arbitrary function within arbitrary memory. Brilliant; bravo. I salute the ingenuity of this one.