They aren’t very vulnerable to hacker attacks, frankly this sort of thing is just a niusance.
Financial attacks ditto. The Saudis have huge international investments, very diversified. The Russians couldn’t touch them without, somehow, attacking everyone, including their own private stashes abroad.
Worst they could do, short of nukes, to the Saudis, is fund Iran to make trouble. Or give Iran nukes. But if the Russians are low on funds, this isn’t in the cards.
They don’t need to conquer, just deny the Saudis the ability to produce, refine, and ship their product. If they do this and do it long enough they will make money doing so. There is nothing like reward to motivate someone to aggression, particularly when the feel aggrieved or injured by the other party. .