Why Bridges Get Drained (And What's Changing)

What you'll learn

• The Worst Year in Crypto Was 2022, and Bridges Were the Reason
• Ronin (March 2022): $625M — Multisig Social Engineering
• Wormhole (Feb 2022) and Nomad (Aug 2022): Smart-Contract Failure Modes
• Multichain (July 2023): $210M — Custody Centralization
• Modular Interchain Security: The Next Generation
• A Builder's Checklist for Bridge Integration

Key terms

Lazarus Group

A North Korean state-sponsored cyber threat actor attributed by the FBI to the Ronin Bridge hack (March 2022, $625M) and several other crypto-targeted attacks. Specializes in social-engineering APT campaigns against crypto custodians.

Sysvar instructions (Solana)

A Solana mechanism for inspecting other instructions in the same transaction. The Wormhole February 2022 hack exploited a flawed use of sysvar instructions in the Solana Wormhole program.

Trusted computing base (TCB)

The set of all components that must be correct for a system to be secure. For bridges this includes every committee, every smart contract on every destination chain, every upgrade path, every off-chain process — any one component failing can destroy the bridge.

Initialization bug (Nomad)

A class of smart-contract bug where uninitialized storage slots have unintended valid values. Nomad's August 2022 hack used a zero-hash trusted root that was treated as valid because uninitialized Merkle proofs also hash to zero.

Operational centralization

When a system that is technically decentralized (e.g., MPC committee, multisig) is effectively controlled by a single party operationally — through employer relationships, shared infrastructure, or jurisdictional concentration. Multichain's 2023 collapse exposed this risk.

Modular interchain security

The post-2022 design pattern of stacking multiple independent verification mechanisms (multi-committee, ZK light client, restaking, rate limits, dispute windows) so that no single mechanism's failure can compromise the bridge.

Restaking (EigenLayer)

A mechanism for staked ETH to be used as economic security for additional services beyond Ethereum consensus, including cross-chain attestor sets. An attack on a restaked attestor set costs at least the value of slashed restaked ETH.

Circuit breaker

A bridge-level mechanism that pauses outflows or imposes rate limits when anomalous activity is detected. Standard in post-2022 bridges; absent or weak in many pre-2022 designs.

Aggregation ISM

A Hyperlane Interchain Security Module that requires multiple sub-ISMs (e.g., multisig + ZK light client + routing) to all approve a message before acceptance. The ISM-level realization of modular interchain security.

Bug bounty (bridge context)

A public reward program (often via Immunefi) for ethical disclosure of bridge vulnerabilities. Major bridges run multi-million-dollar bounty programs and treat bounty submissions as a primary discovery channel.