Vyper is an open-source, contract-oriented programming language that focuses on simplicity, security, and auditability. It is designed for writing smart contracts on the Ethereum Virtual Machine (EVM). However, it has recently been subject to a critical vulnerability known as CVE-2024-24564, affecting version .3.10 and earlier. This post aims to provide a detailed explanation of the vulnerability, its potential impact, and recommended mitigation strategies.

Vulnerability Details (CVE-2024-24564)

The vulnerability lies in the built-in extract32(b, start) function of the Vyper language. This function is designed to extract 32 bytes of data from a byte array, b, starting at a specified index, start. However, if the start index provided results in updating the b byte array, the function might unintentionally read and return data from dirty memory. Consequently, this leakage of sensitive information could lead to severe security implications in smart contracts.

A simple code snippet exhibiting the vulnerability is shown below

def vulnerable_function(b: bytes, start: uint256) -> bytes32:
    return extract32(b, start)

In this example, if the value of start were to inadvertently modify the b byte array, dirty memory would be read and returned by the extract32 function, posing security risks.

Original References

- Vyper GitHub Repository: https://github.com/vyperlang/vyper/
- Vyper Documentation: https://vyper.readthedocs.io/
- Ethereum Stack Exchange: https://ethereum.stackexchange.com/questions/tagged/vyper

Exploit Details

The memory leak vulnerability could potentially be exploited by an attacker who can manipulate or control the input parameters of the extract32 function. By providing a start index that leads to updating the b byte array, the attacker could force the extract32 function to read and possibly disclose sensitive information stored in the contract or memory. The attacker could then use this information to compromise the security and integrity of the smart contract.

Mitigation Strategies

To address this vulnerability, developers using Vyper must ensure that they are using a version newer than .3.10. Upgrading to the latest version will ensure that your smart contracts are not susceptible to this specific vulnerability.

Additionally, developers should always validate input parameters of critical functions before usage, especially if the function interacts with memory or storage. This can help prevent unintended side effects from occurring. Regular code audits and security reviews are also highly recommended to identify and tackle vulnerabilities in smart contracts proactively.

Conclusion

CVE-2024-24564 is a critical memory leak vulnerability in the Vyper smart contract language that could potentially expose sensitive information and compromise smart contract security. Developers are urged to upgrade to newer versions of Vyper and implement proper input validation and safety measures in their smart contracts to mitigate the risk posed by this vulnerability. Moreover, regular code audits and security reviews are essential for maintaining secure and robust smart contract applications.

Timeline

Published on: 02/26/2024 20:19:05 UTC
Last modified on: 02/26/2024 22:10:40 UTC