Smart Contract / Hash Collisions with Multiple Variable Length Arguments

Description

Hash Collisions With Multiple Variable Length Arguments is a vulnerability that occurs in Smart Contracts written in Solidity (SWC). According to the CWE directory, this vulnerability occurs when the same hash is assigned to multiple strings of different lengths, allowing for the execution of malicious code. This vulnerability can lead to the execution of malicious code, resulting in the compromise of the system. It is also listed as a vulnerability in the OWASP Testing Guide.

Risk

The risk of Hash Collisions With Multiple Variable Length Arguments is high, as it can lead to the compromise of the entire system, resulting in the loss of important data. This vulnerability can also be used to bypass security measures, allowing attackers to gain access to the system with ease.

Solution

The best way to prevent this vulnerability is to use Secure Hash Algorithms (SHA-256 or SHA-512) when creating hashes. These algorithms are designed to generate unique hashes for strings of different lengths. Implementing these algorithms when creating hashes can help protect against hash collisions.

Example

The following example code demonstrates a vulnerable contract written in Solidity (SWC):

contract Example {
    function exampleFunction(string _a, string _b) public view returns (uint) {
        return uint(keccak256(_a, _b));
    }
}

This code is vulnerable, as it uses the keccak256 hash algorithm which is susceptible to Hash Collisions with Multiple Variable Length Arguments.