Levels

1. Hello Ethernaut

2. Fallback

1. Notice the onlyOwner modifier
• it prevents anyone other than the owner from calling contract.withdraw
• this is where I found out more about modifiers What are solidity modifiers?

2. There are two lines in the smart contract that allows us to change the owner of the smart contract with the following line owner = msg.sender;
• in contribute and receive

3. Notice that receive looks a little different from other function. Did some research and found out that receive() external payable is a fallback function that is called "if Ether are sent to the contract and no calldata are provided"

3. Fallout

Solution

1. Notice that there is only one function that allows change of owner which is Fallout

2. Tries to call contract.Fallout but realised it is undefined.

3. then notice the typo it is actually Fal1out , the second l is actually a 1

4. Just execute the following in the browser console and you will become the owner

Takeaways

• Turns out that it has to be a typo else the challenge will not work, the challenge simulates a typo where the constructors is misnamed and became a public function instead.

• Seems like a bad idea to even define constructors by the contract name, note to myself, maybe just use the constructor keyword?

4. Coin Flip

1. I tried to be fancy here and did a for-loop only to realised that the challenge prevents that with the following

Takeaways

• external is like public but cannot be called internally

Next -

Ethernaut Walkthrough - Part 2