Well, the splash page states:
“A select group of veterans from the Israeli elite intelligence units that specialises in tailored solutions to complex business and litigation challenges”
So I’m guessing it’s Israeli intelligence.
Black Cube certainly has former Mossad in it and they do hype that for marketing reasons, but no, Black Cube is one of many private business intelligence firms such as GPW (J.S. Held) and K2.
All of them are dirty and work for people who are shady as heck, including governments and political parties.
I work in military contracting and all of them have tried to recruit me at various times, presumably for smuggling of some kind. (I can fly anything, anywhere, very well.) Not for me.