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Aptos (LayerZero) logoAptos (LayerZero)


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Tokens:

Description

This project includes unverified contracts (CRITICAL).

Aptos Bridge is built on top of LayerZero protocol and is a token bridge for transferring assets from Ethereum to Aptos. It leverages an oracle and relayer for cross-chain security for the protocol.

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Risk summary

Note: This project's overview requires more research and might not present accurate information. If you want to contribute you can edit the information on Github. Alternatively you contact the project team on Twitter and encourage them to contribute a PR.

Technology

Principle of operation

Aptos Bridge is a Token Bridge. It locks tokens in Ethereum escrow and mints tokens on Aptos.

Oracles and Relayers

Note: This section requires more research and might not present accurate information.

Aptos Bridge is built on top of LayerZero protocol. LayerZero relies on Oracles to periodically submit source chain block hashes to the destination chain. Once block hash is submitted, Relayers can provide the merkle proof for the transfers. Token Bridge owner can withdraw all funds from the bridge escrow after placing the bridge in an emergency withdrawal mode that will allow them to transfer all tokens out after 1 week delay.

  • Users can be censored if oracles or relayers fail to facilitate the transfer (CRITICAL).

  • Funds can be stolen if oracles and relayers collude to submit fraudulent block hash and relay fraudulent transfer (CRITICAL).

  • Funds can be stolen if token bridge owner (currently EOA) enables emergency withdrawal and users do not exit with their funds within a week (CRITICAL).

  • Funds can be stolen if token bridge owner (currently EOA) sets WETH contract address to a malicious contract that will allow the owner to steal user's ETH (CRITICAL).

Permissioned Addresses

The system uses the following set of permissioned addresses:

Aptos Multisig 0x9710…5F05

Bridge owner, can setup tokens, fees, WETH token address (potentially malicious). Can withdraw all the funds from the Escrow after unlocking emergency withdrawal with 1 week delay.

Participants of the 2/4 Aptos MultiSig.

LayerZero Relayer 0x902F…089E

Contract authorized to relay messages and - as a result - withdraw funds from the bridge.

LayerZero Relayer Admin owner 0x76F6…d6e5

Can upgrade LayerZero relayer contract with no delay.

LayerZero Oracle Admin owner 0x7B80…e6c8

Can upgrade LayerZero oracle contract with no delay.

LayerZero Multisig 0xCDa8…4C92

The owner of Endpoint, UltraLightNode and Treasury contracts. Can switch to a new UltraLightNode for an Endpoint. Can switch proof library for an UltraLightNode and change Treasury.

Participants of the 2/5 LayerZero MultiSig.

Smart Contracts

Note: This section requires more research and might not present accurate information.

The system consists of the following smart contracts:

TokenBridge 0x5000…d907

Aptos Token Bridge. This contract stores the following tokens: USDC, USDT, WETH.

Endpoint 0x66A7…d675

LayerZero Ethereum Endpoint.

UltraLightNodeV2 0x4D73…78E2

LayerZero UltraLight Node V2. Used by oracles to checkpoint source chain block hashes.

TreasuryV2 0x3773…e34d

LayerZero Treasury V2.

LayerZero Proof Library 0x0724…df89

The current deployment carries some associated risks:

  • Funds can be stolen if a contract receives a malicious code upgrade. There is no delay on code upgrades (CRITICAL).

  • the source code of unverified contracts contains malicious code (CRITICAL).