What does "it" represent in the following sentence?

I read the following sentence on the leading corporation in a corruption-infested country.

Its path to the top was strewn with secret deals, price fixing,
bribery, tax evasion and more, all of it overseen by an
ultrasecretive, ultrarich family ready to use every means at its
disposal to stay in command.

What does the pronoun "it" refer to?

Given the pronoun "it" represents a singular noun, logically, "it" in the sentence apparently refers to "its path to the top."
But the phrase "all of it" somehow sounds plural.