Title: Ethereum: Zk Rollups – Security Under Threat

Introduction

The Ethereum network has long been considered one of the most secure and decentralized blockchain platforms available today. Its innovative use of zk-rollups, a cutting-edge concept in cryptocurrency transactions, has made it an attractive option for users who want to maintain privacy and control over their financial data. However, as with any technology, vulnerabilities can exist.

Zk Rollup Zk-Snark Test System

Zk rollups are based on the security of zk-snark, a zero-knowledge verification system developed by Oded Maler and Guy Sussman in 2016. This concept allows transactions to be verified without revealing their contents, thus maintaining user privacy.

The process involves breaking complex transactions into smaller, verifiable parts called “block fragments.” A network of nodes then verifies each block fragment, ensuring that all transactions in the block are legitimate and have not been tampered with. Once verified, the block fragments are combined to form a single block, which is then added to the Ethereum blockchain.

Vulnerability: Malicious Relay Proof Using Incomplete Transactions

Now, consider the scenario where a malicious relay creates a proof using incomplete transactions in a batch (e.g., more than 10 transactions with empty entries). This malicious action would allow them to create a false narrative about the state of their blockchain. To accomplish this:

• Block: The malicious relay creates multiple blocks containing different sets of incomplete transactions.

• Proof Generation

  : They generate a proof using zk-snark that links these batches, creating the illusion that all valid transactions are included in the batch.

• Relay: The malicious relay retransmits this proof to other nodes in the network, making it appear that all transactions have been verified.

Security Risks and Consequences

By generating a false proof of state transition, the malicious relay gains several benefits:

• Increased Resilience: If a node or group of nodes fails to verify the transaction, they can still accept the proof and add it to their local copy of the blockchain.

• Reduced Detection Risk: Using incomplete transactions makes it harder for validators to detect the malicious retransmission.

However, this strategy also poses several risks:

• Increased attack surface: By making it easier for malicious actors to create false evidence, the overall security posture of the network is compromised.

• Network segregation: As more nodes fall victim to the malicious relay scheme, the integrity of the blockchain can be compromised, potentially leading to a breakdown in network segregation.

Mitigation strategies

Several measures can be implemented to address these vulnerabilities:

• Blockchain segregation: Implementing segregation of concerns (SoC) techniques and smart contract-based isolation mechanisms can help prevent malicious actors from compromising critical components.

• Improved network monitoring: Improved node monitoring and anomaly detection capabilities can more effectively identify potential threats.

• Smart Contract Auditing: Regularly auditing and testing smart contracts for vulnerabilities can help mitigate the impact of successful attacks.

By recognizing these risks and implementing effective mitigation strategies, Ethereum developers can work to create a more secure and resilient zk-rollup-based network that balances user privacy with the need for strong security measures.