18
votes
Accepted
Explain "griefing" attack on Aave flash loan
Developer @ Aave here, good questions.
It depends on your contract. But a simple one would be:
Contract A has funds and the executeOperation()
Contract B calls flashloan(), passing in Contract A as ...
- 316
8
votes
Flash loan security considerations and attacks
As we work on flash loan attack debriefs, we can gather a lot of information about what could have been taken as preventative measures. It's important to understand how these flash loans work before ...
- 12.4k
6
votes
Accepted
Double Flash Loan
You can actually do a double flashloan, but the success will depend on the total amount of gas consumed in the transaction.
In fact, you don't need to have two contracts and you can request the two ...
- 3,409
4
votes
What time Ethereum gas fee is calculated?
When you create a transaction you set two parameters:
gas: Maximum amount of gas to be used
gasPrice: Price to pay for each gas unit
To execute the transaction your account needs to have at least ...
- 30.3k
4
votes
Accepted
How to Tranfer Remaining NFTs And/Or Tokens Out of A Hacked Ethereum Wallet
You are in the correct path. MEV can do this for you.
You can use MEV to submit two transactions with the following properties:
Either both or none of them go through
They should be executed in the ...
- 30.2k
4
votes
Accepted
How does flashloan guarantee the borrowed ether/token will be paid back?
it's all done in one function, so you can revert if the money isn't paid back. (e.g. I send you 100 bucks, you do what you want with it, but the txn reverts if it's not back in my hand by the end of ...
- 3,920
3
votes
Accepted
Why I need smart contract for arbitrage
I think reasons are multiple:
if you sign the transaction to interact with the exchanges contracts directly with an EOA you must know the exact best amounts to optimise your gain since the beginning.
...
- 500
3
votes
How to Tranfer Remaining NFTs And/Or Tokens Out of A Hacked Ethereum Wallet
I was in the same situation - my credentials were stolen when i connected metamask to scam website that looked like legit one. ETH scavenger was eating all my ETH in wallet and my NFTs were stuck in ...
- 31
3
votes
How to conduct a flash loan on PancakeSwap?
PancakeSwap is a fork of Uniswap V2, which allows flashswaps. An example of flashswap using Uniswap V2 can be found here: https://github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/examples/...
3
votes
Flash loan security considerations and attacks
Flash loans violate two common intuitive assumptions.
1. "Nobody has that much ETH"
Problems can arise when for example:
Your contract uses a non-linear formula with an ETH amount as ...
- 10.5k
3
votes
Flash loan security considerations and attacks
Generally speaking, if your system gives the users different terms under different scenarios, then you need to remember that a user can issue a flash-load attack on it.
For example, if your pool gives ...
- 26.2k
3
votes
Can i use the data returned from 1inch's api swap, to perform a swap from a smart contract? (i.e for flashloans)
Sure. There are a couple examples in the wild but my favorite example is the swapProxy by smye
To get the data from the API disableEstimate=true is a required parameter. Make sure the fromAddress is ...
- 31
3
votes
Cannot estimate gas; transaction may fail
Ok I solved it. I tested my smart contract with hardhat and to check the states I used console.log. For sure that does not work on mainnet (Or even testnet), but on a hardhat forked mainnet it does.
...
- 83
2
votes
Explain "griefing" attack on Aave flash loan
I think the things is: anyone can call the function in contract A means anyone can utilize the funds inside the contract. This can finally used up the funds and it is called a griefing attack.
- 21
2
votes
Accepted
Member "concat" not found or not visible after argument-dependent lookup
It fails because the compiler is looking for the concat function as a member of bytes type.
You can use concat as a regular function
return string(concat(bytes(api0xUrl),
concat(...
- 30.3k
2
votes
Accepted
Failing to borrow from Aave's Lending Pool
The AAVE v2 USDC and USDT tokens use 6 decimals rather than 18. My guess is that you are trying to borrow a trillion million dollars rather than just a million.
This line:
aaveUSDCloan = 1000000 * 10 *...
- 396
2
votes
Flashloan error `reverted with reason string 'SafeERC20: low-level call failed'`
You will need to have tokens of the target assets in the smart contract in order to pay for the premiums
- 21
2
votes
Abitrage with dydx flash loan always reverted
i am trying to make a flash loan too. i saw some codes on how to buy on kyber and sell on uniswap
https://github.com/jklepatch/eattheblocks/tree/master/profitable-flashloans/24-buy-kyber-sell-uniswap ...
2
votes
Accepted
Is this smart contract code malicious?
TL;DR Yes, it's a scam.
The functions used are hidden in the Manager object imported with this line import "ipfs://Qmf5Ua79ZT8ERFa9q32fQtGuWkqk1eZXxnzRdeTi6wvzUy". I cannot see that code, ...
- 3,630
2
votes
Accepted
Can a flash loan used to flash attack a smart contract?
Yes, it is possible.
Moreover that technique was already used against MakerDao, read https://forum.makerdao.com/t/urgent-flash-loans-and-securing-the-maker-protocol/4901.
It can be fixed by requiring ...
- 30.3k
2
votes
Accepted
Getting a compile error every time I try to compile a contract with Brownie that includes an import statement from the web
In order to import directly from github, you need to add the dependencies to your brownie-config.yaml file.
ie if you're trying to import from https://github.com/aave/protocol-v2/blob/master/contracts/...
- 12.4k
2
votes
Approving tokens after flash loan
Yikes. Turns out this was happening since I wasn't paying back my flashloan. 🤦
- 31
2
votes
Flash loan basics
This tutorial shows you how to deploy a smart contract to receive and use a flashloan from Aave V3.
Aave V3 flash loan with Hardhat
This one is a step-by-step guide on how to develop and deploy the ...
2
votes
Flash Loan Arbitrage Bot
in general, your app needs to have two parts:
A program that finds arbitrage opportunities.
A program that gets the flashloan and uses it to act on the arbitrage opportunity.
This tutorial shows you ...
2
votes
Accepted
Can a sandwich attack be designed using 1 flashloans and no outside capital? attacker tx, victim tx, attacker tx bundled with 1 flash loan?
Flashloans lifecycle is limited to a single transaction, and cannot be used in a sandwich attack.
- 23k
1
vote
BSC Flashloan getting Pancake:Locked
Looking at the tenderly trace the swap function in PancakePair is being called within another call to swap in the same PancakePair.
If you look at the swap function definition
function swap(uint ...
- 30.3k
1
vote
How haven't flash loans completly destabilized the ethereum blockchain?
You are only partially correct. Flash loans need to be paid back within the same transaction. And transactions don't typically depend on each other - if one transaction in a block reverts, the next ...
- 30.2k
1
vote
Solidity Expected '(' but got identifier
You have unnecessary "," in your function parameters. Change to this
function startArbitrage(
address token0,
address token1,
uint amount0,
uint amount1
- 1,256
1
vote
How are UniSwap V2 flash swaps recorded
Yes, a flash swap will trigger the same events as a normal swap.
The only difference is that in a flash swap, the contract that called the swap can perform some arbitrary code between the moment it ...
- 3,630
1
vote
Accepted
Struct on delegatecall
Solution:
Have to pass a tuple instead to abi.encodeWithSignature, according to the docs: https://docs.soliditylang.org/en/v0.8.6/abi-spec.html#mapping-solidity-to-abi-types
So it would be:
execute(...
- 948
Only top scored, non community-wiki answers of a minimum length are eligible