Summary

The custom _msgSender() logic for meta-transactions could result in incorrect address extraction, potentially leading to incorrect sender identification during contract interactions.

Finding Description

In the MembershipFactory.sol contract, the _msgSender() function is overridden to handle meta-transactions. This function uses low-level assembly code to extract the sender address. If there is a mistake in how the msg.data is processed, this could lead to incorrect sender addresses being used in contract functions, breaking the integrity of authorization checks and potentially allowing attackers to bypass access control.

The issue arises when the custom _msgSender() logic does not properly decode or miscalculates the address. If a malicious actor can exploit this, they could impersonate other users or contracts, leading to unauthorized actions being executed.

Security Guarantee Violated: The issue breaks the authentication and authorization guarantees of the contract, as incorrect sender identification can bypass role-based access control and allow unauthorized operations.

Vulnerability Details

• Location: MembershipFactory.sol, _msgSender() function.

• Cause: The use of assembly to extract the sender address is complex and might fail if msg.data is not structured correctly or if the address extraction is incorrect due to a failure in how the data is encoded or decoded.

The vulnerability could lead to an attacker bypassing the role-based access control, allowing them to execute functions restricted to other roles or addresses.

Impact

This vulnerability could have severe consequences if an attacker can impersonate an authorized user. For example, a malicious actor could perform actions such as creating DAOs, joining DAOs, or modifying DAO configurations under false pretenses. This undermines the integrity of the contract and exposes it to exploitation.

The impact is critical because unauthorized access could lead to a breach in governance, token minting, or other sensitive actions within the contract.

Proof of Concept

A proof of concept would involve a scenario where a user interacts with the contract by sending a meta-transaction. If the assembly code fails to properly decode the sender address, an attacker could craft a malicious transaction that masquerades as another user and perform unauthorized actions.

Example:

Recommendations

To fix this issue, ensure the _msgSender() function is correctly implemented with additional checks to prevent misidentifying the sender. Instead of using low-level assembly for extracting the sender, consider using a safer approach or implementing more thorough checks and validation for msg.data.

Fixed Code Snippet:

This version adds a validation step to ensure the msg.data contains sufficient length and only extracts the address when it is valid.

File Location:

MembershipFactory.sol