Worked example · 2026-10

FlashLoopAdapter — the Safe module asked the caller whether it was a Safe with the module enabled, and a fake Safe said yes — FlashLoopAdapter (Aave V3 loop Safe module) / Ethereum — 2026-10-01

Loss

~114 ETH (~$305K) from two Safe wallets with leveraged Aave V3 positions. Aave V3 itself was unaffected (Stani Kulechov: "zero effect").

OAK Techniques observed

OAK-T9.004 (Access-Control Misconfiguration — primary, confirmed. open() and close() authorised callers by calling isModuleEnabled on msg.sender — a check the caller answers about itself. A fake Safe contract returning true passed it. Using a Morpho flash loan, the attacker repaid ~1,335 WETH of a victim Safe's Aave debt and withdrew ~1,306 weETH of collateral, keeping the difference. See techniques/T9.004-access-control-misconfiguration.md). OAK-T9.002 (Flash-Loan-Enabled Exploit — capital source). Same class as SquidRouterModule: a Safe module whose authorisation is satisfiable by anyone.

Attribution

pseudonymous.

Key teaching point

Never ask the caller to vouch for itself. Identity checks must be against state the module controls — a registry of Safes that enabled it, or a Safe factory/proxy code-hash check — not a view function on msg.sender.