Introduction Imagine you’re a conductor, leading an orchestra of a hundred musicians. Each musician is playing their part, but they need to harmonize, to come together at just the right moments. This is the essence of concurrency in programming, and ...
A honeypot is a smart contract that purports to leak cash to an arbitrary user due to a clear vulnerability in its code in exchange for extra payments from that user. A honeypot is a trap to catch hackers. Combining two exploits, reentrancy and hidin...
Before transactions are added to the block, they are first sent to the transaction pool (mempool). In the mempool, the miners mine the transaction with the highest gas fee and add it to the block before going to the transaction with the lower gas fee...
Denial of Service by rejecting to accept Ether. There are many ways to attack a smart contract to make it unusable. One exploit is a denial of service by making the function to send Ether fail. The solidity fallback function is executed if none of th...
A miner can manipulate the block.timestamp which can be used to their advantage to attack a smart contract. block.timestamp can be manipulated by miners with the following constraints: it cannot be stamped at an earlier time than its parent it cann...
Signature Replay is using the same signature to execute transactions multiple times. The benefit of signature replay is to reduce the number of transactions on-chain and perform a gas-less transaction, called meta transaction. Take, for example, a mu...
In Ethereum, accounts can either be Externally Owned Account, (EOA) or Contract Account. A developer may decide to allow only Externally Owned Addresses (EOA) to interact with his contract, then the developer can add a check via extcodesize, which re...
Overflow Overflow is a state uint (unsigned integer) reaches its maximum value, and the next element added will return the default value. uint8 can hold values within the range(0, 255), if the value of an arithmetic operation becomes greater than 255...
Introduction A reentrancy attack in solidity repeatedly withdraws funds from a smart contract and transfers them to an unauthorized contract until the funds have been exhausted. The attack occurs when a smart contract function temporarily gives up co...
