Multichain incident, 2023-07-06

Multichain described its security as MPC — a threshold signature scheme in which key shares are spread over several nodes. In practice, the company later admitted that all operational funds and investments had been under one person's control, and once he was detained nobody else could operate the bridge (DL News). Whatever the cryptography, the governance was a single point of failure.

The July outflows came after weeks of unexplained delays, which in hindsight were the warning sign. Chainalysis noted that the attacker did not swap out of freezable assets like USDC, an unusual choice for an outside thief and one reason the "hack or rug" question stayed open (Chainalysis).

For users the lesson is about who can actually move the money. "MPC" or "multisig" describes a mechanism; it says nothing about whether the shares are held by independent parties. A bridge that cannot publish who holds the shares should be treated as custodial.

Multichain also shows how a bridge failure spreads. Tokens it minted were the main version of USDC, ETH and BTC on several chains, so lending markets, DEX pools and users who had never touched the bridge inherited its risk. When a chain's dominant stablecoin is a bridged wrapper, the chain's DeFi is only as safe as that bridge.

At the time

The weeks of stuck transfers before July were the moment to act: users who withdrew Multichain-bridged assets back to their native chains, or swapped them for native assets, during the delays avoided the loss. Waiting for an official explanation proved costly.

Now

Treat unexplained, prolonged delays from a bridge as a reason to exit, not to wait. Prefer bridges whose signer set and organisations are published, or native/canonical bridges whose security is enforced on-chain. Our route pages track when a bridge stops quoting, which is often the first public signal.