Resources

People often ask me "How did you learn how to hack?" The answer: by reading. This page is a collection of the blog posts and other articles that I have accumulated over the years of my journey. Enjoy!

EigenLayer introduces restaking on Ethereum. This allows staked assets to secure other applications, known as Actively Validated Services (AVS) rather than just Ethereum. EigenLayer runs alongside Ethereum, so its implementation is highly security-sensitive.

The EigenLayer sidecar is an off-chain worker supporting the main logic in the smart contracts. It listens for on-chain events, processes the data and performs computations on it, such as Rewards. AVSs submit reward details on the chain to the RewardsCoordinator.sol contract, where the sidecar process processes the amount and duration information.

The Solidity contract attempts to do input validation on the duration: it must be a divisor of CALCULATION_INTERVAL_SECONDS. This is checked by doing duration % CALCULATION_INTERVAL_SECONDS == 0. Technically, zero satisfies this requirement.

Within the off-chain codebase, there is a SQL query that performs division. This leads to a divide-by-zero error in the database. They found this issue by first seeing the division within the SQL query (sink) and tracing it all the way back to the source. I typically don't trace divide by zero bugs this way so that was interesting to see.

The impact is slightly dubious to me. A crash or exit doesn't necessarily mean a Denial of Service in all cases. Error handling and continuation need to be taken into consideration. In this case, since the SQL query failed, all AVS operators' sidecar operations for reward calculations would be halted. A good bug and an interesting trace!