Smart contract exploitation, EVM internals, and Web3 security. Each challenge is documented as a complete security research article — explaining not just the exploit, but why it works and how the underlying Solidity or EVM behaviour makes it possible.
5
Challenges Solved
Medium
All Difficulties
EVM
Focus Area
On-Chain Storage Transparency
Ethereum's `private` keyword does not prevent on-chain storage reads. By using `eth_getStorageAt` to retrieve the `encryptedFlag` stored in slot 0, and then scanning historical bot transactions to find the XOR key that produces a value matching `hashedFlag` in slot 1, the `talk()` function can be called with the correct key to set `solver = msg.sender`.
delegatecall Storage Collision + Deterministic Contract Deployment
The `createPortal` function in `PortalStation` performs a `delegatecall` to a hardcoded destination address. Because contract deployment addresses are deterministic (`keccak256(RLP([deployer, nonce]))`), burning nonces 0–129 with dummy contracts causes the 130th deployment to land exactly at the `orcKingdom` destination address. The attacker-controlled contract's `connect()` function then writes `true` to `isPortalActive["orcKingdom"]` through the delegatecall, entirely within `PortalStation`'s storage.
Bit Manipulation & Blockhash Dependency
A multi-condition unlock function relies on byte truncation and a blockhash-dependent password. Understanding how Solidity handles bytes vs uint endianness reveals how to satisfy all conditions simultaneously with one crafted value.
Reentrancy via ETH Transfer Before State Update
An ETH transfer fires before the sale item is deleted from state. A malicious receive() function re-enters the purchase function while the item still exists, triggering a second payout and draining the contract balance.
delegatecall Storage Collision + Deterministic Contract Deployment
The createPortal function performs a delegatecall to a hardcoded destination address. Because CREATE deployment addresses are deterministic (keccak256(RLP([deployer, nonce]))), burning nonces 0-129 causes the 130th deployment to land exactly at the target address, letting an attacker-controlled contract write through delegatecall into the caller's storage.