Common Vulnerabilities in Bridges
summary
Most audited bridges fail on concrete implementation errors: a replay attack via 256→32 casting allowed reconstructing valid proofs and earned a roughly $1,000,000 bounty in a white‑hat report, unrestricted external calls on Arbitrum let attackers drain stray ERC‑20 tokens, mismatched decimals (USDC/USDT 6 vs 18) can multiply balances by 10^12, a single malicious token can veto batch execution, return‑gas bombs and ZK‑EVM limits ( ~1,000 add ops ) exhaust resources, OpenZeppelin index handling and off‑chain multisig routes enable full compromise.
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chapters (8)
- 0:00Bridge vulnerabilities intro
- 1:53Replay attacks and nonces
- 3:16Unrestricted external calls
- 5:04ERC20 token pitfalls
- 6:54Gas bombs and exhaustion
- 8:40Trusted roots and index
- 9:21Hashing and message integrity
- 9:41Consensus and offchain risks
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