Claude explains the $71M @arbitrum clawback: What this transaction is Tx: 0x5618...0f6b on Arbitrum, block 454686044, April 21, 2026 03:35 UTC From: 0x5d39...7Ccc — labeled on Arbiscan as “Kelp DAO Exploiter 1” To: 0x0000000000000000000000000000000000000DA0 — a special system/recovery sink (not the normal 0x...dEaD burn address) Value: 30,765.667 ETH (~$71M) — effectively the entire Arbitrum-side balance of the attacker’s hub wallet Tx type: ArbitrumUnsignedTxType (EIP-2718 type 0x65 / 101) The “type 101” is the key. That is not a user-signed transaction — a normal EOA physically cannot produce one. ArbitrumUnsignedTxType is an ArbOS system transaction that only the chain itself (via the sequencer / ArbOS upgrade path controlled by the Arbitrum Security Council) can inject. It bypasses the attacker’s private key entirely. The remediation (this tx): Arbitrum’s Security Council used its emergency powers to inject an ArbitrumUnsignedTxType that forcibly moved the attacker’s full 30,765 ETH from the hub address into a protocol-controlled recovery sink (0x...0DA0). Why it’s “extraordinary” Arbitrum did not perform a reorg or historical rewrite — the chain’s ordering is intact. Instead, the Security Council used a privileged state-override transaction type that is part of ArbOS but has essentially never been used before. It is functionally a state-level clawback: the attacker’s private key still signs txs, but that address’s ETH was moved by the chain itself. This is the mechanism Arbitrum’s progressive-decentralization docs reserve for “catastrophic” emergencies (12-of-N Security Council action), and this is one of the clearest public demonstrations of it being invoked. Note that it only recovered the Arbitrum leg of the theft — the ~75,700 ETH on Ethereum is outside Arbitrum’s control and remains with the attacker, which is why Aave is still facing up to ~$230M of potential bad debt on the Ethereum side. Sources: Arbiscan tx: arbiscan.io/tx/0x5618044241d… Arbitrum Docs — ArbOS / Sequencer forced inclusion: docs.arbitrum.io/run-arbitru… Arbitrum Foundation — progressive decentralization & Security Council: docs.arbitrum.foundation/sta…