you're asking the wrong question. mainly because bitcoin mining is done with ASICs and not general purpose computers. I would be surprised if the bitcoin network hashrate isn't higher than all the general purpose computing power in the world combined (converted to double SHA256 hash rate).
Basically, the longest chain is considered correct. And it has to work that way. It's why BTC is sybil-resistant.
So the attack is to get >51% of the hash power together, then mine in secret, creating a perfectly valid longer chain with a different tx history.
Publish it, and watch the world burn.