A massive crypto heist drained billions from Binance-linked wallets using a clever exploit of Ethereum's permission system, and it's bad news for exchange security and crypto holders' trust.

• Attackers funded a fresh wallet through a mixer, a service that scrubs crypto's trail so it can't be traced back to its source.
• That wallet built a special tool designed to sweep an entire wallet clean in one shot.
• The hackers somehow tricked Binance into signing permission slips that handed over control of its wallets, exploiting Ethereum's feature that lets a wallet delegate control to a program.
• Using that stolen permission, they moved huge sums, around 195,000 Ethereum and 780 million dollars in USDC, out of Binance's wallets and into their own.
• Total losses in the attack reached into the billions, making it one of the largest crypto thefts on record.

Outlook: Expect exchanges to tighten how they approve and sign wallet permissions, and regulators and security researchers will likely scrutinize Binance's signing process closely in the coming weeks.