Title: Ethereum: Zk Rollups – Security at Risk

Introduction

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

Zk Rollup Zk-Snark Proof System

zk rollups rely on the security of zk-snark, a zero-knowledge proof system developed by Oded Maler and Guy Sussman in 2016. This concept allows transactions to be verified without revealing their contents, thereby preserving user data.

During the process, complex transactions are broken down into smaller, verifiable pieces called “block chunks.” Each block fragment is then verified by a network of nodes, ensuring that all transactions within the block are legitimate and have not been tampered with. Once verified, the block fragments are merged into a single block, which is then added to the Ethereum blockchain.

The vulnerability: Malicious intermediaries create proof using incomplete transactions

Now consider the scenario where a malicious intermediary creates proof using a batch of incomplete transactions (for example, 10+ transactions with empty inputs). This malicious action would allow them to create a false narrative about the state of their blockchain. To achieve this:

• Batching: The malicious intermediary creates multiple blocks that contain different incomplete transactions.

• Proof Generation: A proof is generated using zk-snark that connects these batches, giving the illusion that all valid transactions are in the batch.

• Relayer

  : The malicious intermediary relays this proof to other nodes in the network, making it appear as if all transactions have been verified.

Security Risks and Consequences

By generating false proof of state transitions, the malicious intermediary gains several benefits:

• Increased Resilience: If a node or group of nodes cannot verify a transaction, it can still accept the proof and add it to its local copy of the blockchain.

• Reduced Detection Risk: Using incomplete transactions makes it more difficult for validators to detect malicious relays.

However, this strategy also carries several risks:

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

• Network segregation: As more nodes fall victim to the malicious proxy scheme, the integrity of the blockchain may be compromised, leading to a failure of network segregation.

Mitigation strategies

There are several measures that can be implemented to address these vulnerabilities:

• Blockchain Segregation: The use of Separation of Concerns (SoC) techniques and smart contract-based segregation mechanisms can help prevent malicious actors from compromising critical components.

• Improved Network Monitoring

  : Improving node monitoring and anomaly detection capabilities can more effectively identify potential threats.

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

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