Security of Cross-Chain Protocols: An Analysis Using LayerZero as an Example

The security issues of cross-chain protocols have always been an important topic in the Web3 field. In recent years, the losses caused by cross-chain protocols have ranked first among various blockchain security incidents, and their importance even exceeds that of Ethereum's scalability solutions. The interoperability of cross-chain protocols is a core requirement for connecting Web3 networks, but the public's understanding of the security levels of these protocols is limited.

Taking LayerZero as an example, its design architecture employs Relayers to execute communication between Chain A and Chain B, supervised by Oracles. This design avoids the complex process of requiring a third chain for consensus and verification, providing users with a fast cross-chain experience. However, this simplified architecture also brings potential security risks.

First, simplifying multi-node verification to a single Oracle verification significantly reduces the security factor. Secondly, this design assumes that the Relayer and Oracle are independent of each other, but this trust assumption is difficult to maintain in the long term and does not align with the principles of crypto-nativity.

Some opinions suggest that by allowing more participants to operate relayers through openness, security can be enhanced. However, this practice merely increases the number of participants without fundamentally changing the product characteristics or improving security. LayerZero's relayer is essentially still an intermediary for information transfer, similar to an Oracle, and belongs to the category of trusted third parties.

More seriously, if a project using LayerZero allows modification of configuration nodes, an attacker may replace them with nodes they control, thereby fabricating messages. This risk is even more severe in complex scenarios, and LayerZero itself finds it difficult to address this issue.

Research teams have pointed out that LayerZero has critical vulnerabilities that could lead to user funds being stolen. These vulnerabilities include allowing the sending of fraudulent messages and modifying messages after signing.

In essence, a true decentralized cross-chain protocol should adhere to the "Satoshi consensus", which aims to achieve trustlessness and decentralization. However, LayerZero requires users to trust Relayers, Oracles, and developers who build applications using it, which contradicts the concept of decentralization.

Building a truly decentralized cross-chain protocol remains a challenge. Some experts suggest considering technologies such as zero-knowledge proofs to enhance the security of cross-chain protocols. Regardless of the approach taken, ensuring the security and decentralized nature of cross-chain communication is key to the development of the Web3 ecosystem.