CVE-2023-30629 : Exploit Details and Defense Strategies

Vyper's raw_call with outsize=0 and revert_on_failure=False returns incorrect success value.

Understanding CVE-2023-30629

Vyper is a Pythonic Smart Contract Language for the Ethereum virtual machine. The vulnerability affects versions 0.3.1 through 0.3.7.

What is CVE-2023-30629?

In Vyper versions 0.3.1 through 0.3.7, the Vyper compiler generates incorrect bytecode, leading to unexpected behavior when using 'raw_call' with specific parameters.

The Impact of CVE-2023-30629

The vulnerability allows for incorrect success values to be returned, potentially leading to unexpected results and exploitation by malicious actors.

Technical Details of CVE-2023-30629

The vulnerability arises when utilizing the 'raw_call' function with 'revert_on_failure' set to False and 'max_outsize' equal to 0, resulting in incorrect responses.

Vulnerability Description

Depending on memory garbage, the output of 'raw_call' can be either 'True' or 'False.' A patch is available and expected to be included in Vyper 0.3.8.

Affected Systems and Versions

Vendor: vyperlang
Product: vyper
Versions Affected: >= 0.3.1, <= 0.3.7

Exploitation Mechanism

The vulnerability can be exploited by manipulating parameters in conjunction with the 'raw_call' function.

Mitigation and Prevention

Immediate action is advised to secure systems and prevent exploitation.

Immediate Steps to Take

Apply the provided patch once available
Use the workaround by setting 'max_outsize' greater than 0

Long-Term Security Practices

Regularly update Vyper to the latest version
Follow best practices for smart contract development
Monitor official sources for security advisories and patches