My completely unexpert opinion, informed by listening to all the episodes of Darknet Diaries, agrees with this. US intelligence likes to just bully/bribe/blackmail the supply chain. They've got crypto chops, but I don't recall any terribly sophisticated implants like this one (except Stuxnet, which was likely Israel's work funded/assisted by the US). NK isn't terribly sophisticated, and their goal is money, so that doesn't match either. Russia is all over the place in terms of targets/sophistication/etc because of their laws (AFAIK it's legal for any citizen to wage cyberwarfare on anything and everything except domestically), but this feels a bit beyond anything I recall them accomplishing at a state level. Israeli organizations have a long history of highly sophisticated cyberwarfare (Stuxnet, NSO group, etc), and they're good about protecting their access to exploits. That seems to fit the best. That said, saying "Israeli organization" casts a wide net since it's such a boiling hotspot for cybersecurity professionals. Could be the work of the government, could be co-sponsored by the US, or could just be a group of smart people building another NSO group.