Speaking at Unitize virtual event, Coin Metrics researcher Lucas Nuzzi suggested that one way for exchanges to fight back against the hackers is by renting mining power from online marketplaces.
Six confirmations ticking countdown
Nuzzi conjectured that an exchange which has been hacked could rent enough hashing power through an online marketplace to force a favorable network reorganization:
“So, it is essentially a technique to try and reorg yourself by renting mining power and doing that work where if you’re an exchange and you've been hacked, within those six work confirmations that the network is expecting to be considered final. [...] But through mining, you could potentially, within those six blocks, alter a transaction where your hot wallet has been drained. So, that's one of the approaches through mining.”