5 ms·

This was fun

pcthrowaway 5y ago
If you enjoyed this, you might also like the (much more technical) writeup of the Ethereum pinball machine - https://medium.com/@kanewallmann_71759/an-untrustworthy-pinball-machine-d9dcd07882c https://medium.com/@kanewallmann_71759/an-untrustworthy-pinb... It may assume some knowledge of things like etherscan and the EVM though.
- stavros 5y ago
  This is very interesting, thanks! It reminds me of a friend's adventure, he found a contract containing some ETH that could be called with some more ETH and would send the entire sum back to the caller. He analyzed it a bunch of ways to make sure it wasn't a scam, and then sent some ETH to it. It was a scam. I wonder how it was done, Etherscan didn't show anything and compiling it led to a few bytes of difference between what was compiled and what was deployed.
  - leppr 5y ago
    Interesting, it might use a flaw in the Etherescan contract verification[1]. But in any case, when you expect a honeypot you can and should execute the contract off-chain[2] and examine the resulting state (specifically your account balances) before committing a real transaction. Wallets should really do this by default, but unfortunately there doesn't seem to be a lot of resources available for common goods projects like wallets, so we are stuck with primitive tools. [1]: Like this Unicode RLO exploit for instance: https://krebsonsecurity.com/2021/11/trojan-source-bug-threatens-the-security-of-all-code https://krebsonsecurity.com/2021/11/trojan-source-bug-threat... [2]: https://tenderly.co https://tenderly.co or mainnet forking using hardhat are convenient ways to achieve this.
    - stavros 5y ago
      That's a great tip, thanks! I will relay it, as I don't know much about Ethereum. Can you download and redeploy the compiled contract?
      - leppr 5y ago
        Yes, you can always clone and redeploy any contract with its raw EVM code.
        stavros 5y ago
        Thank you for this tip, which is very concretely worth 1 ETH.
      - pcthrowaway 5y ago
        This might be the same bug reported and fixed in the Ethereum pinball article I shared
        stavros 5y ago
        Yeah, definitely sounds very similar, at least.
  - Aramgutang 5y ago
    There are so many clever ways to code honeypots using obscure peculiarities of Solidity and/or Etherscan that there's little hope of being sure that it isn't a scam just by looking at the code and transaction history. Fortunately, there are tools like Ganache, which you can run with `ganache-cli --fork` to reliably emulate locally what will happen when transactions are sent to mainnet. I would accept no substitute approach when dealing with suspect contracts.
    - stavros 5y ago
      Oh huh, I didn't know Ganache could do that, thank you!

This was fun

If you enjoyed this, you might also like the (much more technical) writeup of the Ethereum pinball machine - https://medium.com/@kanewallmann_71759/an-untrustworthy-pinball-machine-d9dcd07882c https://medium.com/@kanewallmann_71759/an-untrustworthy-pinb... It may assume some knowledge of things like etherscan and the EVM though.

stavros 5y ago
This is very interesting, thanks! It reminds me of a friend's adventure, he found a contract containing some ETH that could be called with some more ETH and would send the entire sum back to the caller. He analyzed it a bunch of ways to make sure it wasn't a scam, and then sent some ETH to it. It was a scam. I wonder how it was done, Etherscan didn't show anything and compiling it led to a few bytes of difference between what was compiled and what was deployed.
- leppr 5y ago
  Interesting, it might use a flaw in the Etherescan contract verification[1]. But in any case, when you expect a honeypot you can and should execute the contract off-chain[2] and examine the resulting state (specifically your account balances) before committing a real transaction. Wallets should really do this by default, but unfortunately there doesn't seem to be a lot of resources available for common goods projects like wallets, so we are stuck with primitive tools. [1]: Like this Unicode RLO exploit for instance: https://krebsonsecurity.com/2021/11/trojan-source-bug-threatens-the-security-of-all-code https://krebsonsecurity.com/2021/11/trojan-source-bug-threat... [2]: https://tenderly.co https://tenderly.co or mainnet forking using hardhat are convenient ways to achieve this.
  - stavros 5y ago
    That's a great tip, thanks! I will relay it, as I don't know much about Ethereum. Can you download and redeploy the compiled contract?
    - leppr 5y ago
      Yes, you can always clone and redeploy any contract with its raw EVM code.
      - stavros 5y ago
        Thank you for this tip, which is very concretely worth 1 ETH.
    - pcthrowaway 5y ago
      This might be the same bug reported and fixed in the Ethereum pinball article I shared
      - stavros 5y ago
        Yeah, definitely sounds very similar, at least.
- Aramgutang 5y ago
  There are so many clever ways to code honeypots using obscure peculiarities of Solidity and/or Etherscan that there's little hope of being sure that it isn't a scam just by looking at the code and transaction history. Fortunately, there are tools like Ganache, which you can run with `ganache-cli --fork` to reliably emulate locally what will happen when transactions are sent to mainnet. I would accept no substitute approach when dealing with suspect contracts.
  - stavros 5y ago
    Oh huh, I didn't know Ganache could do that, thank you!