Dynamic Arrays

[c4-submissions]

Lines of code

https://github.com/Que5/2023-10-ens/blob/main/contracts/ERC20MultiDelegate.sol#L57-L115

Vulnerability details

Impact

The contract can suffer from a Denial-of-Service (DoS) attack if a malicious actor bombards it with a large number of sources and targets until it stops working.

This is because the contract's delegateMulti function processes a potentially large number of sources and targets in a loop. If an attacker can provide a large number of sources and targets, the loop in the delegateMulti function could consume a significant amount of gas, potentially exceeding the block gas limit and causing the transaction to fail.

Proof of Concept

https://github.com/Que5/2023-10-ens/blob/main/contracts/ERC20MultiDelegate.sol#L57-L115

The contract can be exploited through a Denial-of-Service (DoS) attack, specifically a Reentrancy attack. This type of attack occurs when a contract calls another contract (in this case, the _processDelegation, _reimburse, and createProxyDelegatorAndTransfer functions) and, upon receiving a response, continues executing its code.

The potential DoS attack could be executed by providing a large number of sources and targets in the delegateMulti function. This would cause the contract to loop through each source and target, calling the _processDelegation, _reimburse, and createProxyDelegatorAndTransfer functions for each one. If an attacker can trigger this function with a large number of sources and targets, they could consume a significant amount of gas, potentially exceeding the block gas limit and causing the transaction to fail. Moreover an attacker could potentially call the delegateMulti function multiple times in quick succession, causing the contract to enter a state of continuous looping. This could cause the contract to become unresponsive, effectively stopping it from processing any further transactions.

Tools Used

Manual Analysis

Recommended Mitigation Steps

To mitigate the potential Denial-of-Service (DoS) attack, you can implement the following strategies:

1. Limit the size of the input arrays: You can add a requirement that the size of the input arrays does not exceed a certain limit. This can prevent an attacker from overwhelming the contract with a large number of sources and targets.
2. Implement a gas limit: You can add a gas limit to each transaction that calls the delegateMulti function. This can prevent an attacker from consuming too much gas with a large number of sources and targets.
3. Use a counter for the number of transactions: You can implement a counter that tracks the number of delegateMulti transactions executed within a certain period of time. If the counter exceeds a certain limit, you can prevent further transactions until the next period.

Assessed type

DoS

[c4-pre-sort]

141345 marked the issue as duplicate of #31

[c4-pre-sort]

141345 marked the issue as sufficient quality report

[c4-judge]

hansfriese marked the issue as unsatisfactory:
Invalid