Read Only Reentrancy | Hack Solidity (0.8)

[@smartcontractprogrammer]

0:00 - Intro 0:55 - Initialize Foundry 1:16 - Code Hack contract 4:01 - Curve remove_liquidity function 8:31 - Write test 9:57 - Execute test 11:15 - Code Target contract 14:44 - Update Hack contract 17:21 - Update test 18:24 - Execute test again 19:11 - Summary Code github.com/stakewithus/defi-by-example/tree/main/read-only-reentrancy Curve STETH contract github.com/curvefi/curve-contract/blob/master/contracts/pools/steth/StableSwapSTETH.vy Take a course www.smartcontract.engineer/

[@harrydare8191]

A suggestion. You need to author a book on Solidity cause you have vast knowledge

[@juanxaviervalverde]

I support the suggestion. Great mind and a helpful spirit. I'd buy your book.

[@franklucas7542]

Please make more 0.8 hack solidity videos bro, they are helping a ton!

[@0xsuperman]

What does 0.8 mean?

[@xman25ru]

@@0xsuperman solidity version

[@trainwreck1827]

This was very enlightening. Been watching for a while and this is the best.

[@moayaan1911]

New playlist started. Was waiting for this ....

[@navibongo9354]

Great vid! Love ur take on security matters. Would have loved a “how to avoid part”, but this one is fairly simple to prevent. Sry to persist, but could you make a video on bit-shifting in the v2 uniswap contract. With this im referring to the math behind the FixedPoint.uq122x122. Since your bit conversion video, i was left intrigued in how a bit shift would look with the dex values. Seeing as you can apply some logic to all bits in a 122 range for some purpose. Love your videos! Cheers

[@strikeout5]

Curve should have updated all financial state prior to sending the funds out. The reason for this being possible is the callback function in the middle of a state change. tldr; Don't be in an in-between state for important variables when external contract calls are made. Otherwise, the functions in use by other contracts could be manipulated via Read Only reentrancy.

[@muratctp]

Just one question: why virtual price should be higher during remove_liquidity function execution?

[@smartcontractprogrammer]

1. Curve shares is removed 2. ETH is sent back, STETH is not yet sent So the imbalance in ETH - STETH is calculated as "profit". Hence virtual price is higher

[@crypto_peng]

How to avoid this attack? more like flash add-Liquidity, then instantly remove-liquidity to get the reward right?

[@AllenAndersonTaylor]

Would you offer private tutoring? You really understand what you are doing.

[@InSecWeTrust]

so read only happens as well because we'r not following CEI?

[@weinbenderwladimir742]

Great video! Thanks for that! How to prevent these type of attacks when designing smart contracts?

[@bhok5228]

wow, impressive

[@Grucha1998]

This Channel is amazing!! How did you learn this stuff? 🤔

[@smartcontractprogrammer]

google, twitter, youtube

[@juanxaviervalverde]

@@smartcontractprogrammer what youtube channels do you follow to learn?

[@0xivanov]

Hey! Are you using the vim extension for vscode? :)

[@smartcontractprogrammer]

yes

[@Thomasalpha-b9l]

why will the fallback function be triggered?

[@smartcontractprogrammer]

For example calling a function that sends ETH back

[@tele-anonymous]

Hello! What operation system do you use macOs or Linux ?

[@smartcontractprogrammer]

linux

[@adk9321]

What is this contract for?

[@junesuprise]

why foundry and not hardhat?

[@smartcontractprogrammer]

why not?

[@wonjaechoi2762]

What can be a contract 'A' in the code?

[@smartcontractprogrammer]

AMM that returns ETH

[@ngjingxuan4320]

How can we prevent this hack?

[@smartcontractprogrammer]

No general way to prevent it. From the perspective of the Target contract, there is no re-entrancy.

[@raunaquepatra3966]

How to prevent it?

[@ravendonly1]

there is no way to avoid the hack here

[@NishantSingh-zx3cd]

if the developers reverse the sequence of loop such that the 0th element ie. ETH amount comes last in the execution of the iteration, will this vulnerability be resolved? It should look something like this: for i in xrange(N_COINS, 0, -1): value: uint256 = amounts[i] * _amount / total_supply assert value >= _min_amounts[i], "Withdrawal resulted in fewer coins than expected" amounts[i] = value if i == 0: raw_call(msg.sender, b"", value=value) else: assert ERC20(self.coins[1]).transfer(msg.sender, value) log RemoveLiquidity(msg.sender, amounts, empty(uint256[N_COINS]), total_supply - _amount) return amounts

[@smartcontractprogrammer]

i think it will