README.md

Vulnerability Type

This template is for getting started with reentrancy attack PoCs. The reentrancy template implements the callbacks for the following tokens to support reentrancy attacks:

• onTokenTransfer(address, uint256, bytes)
• onTransferReceived(address, address, uint256, bytes)
• tokensReceived(address, address, address, bytes, bytes)
• onERC1155Received(address, address, uint256, uint256, bytes)
• onERC1155BatchReceived(address, address, uint256[], uint256[], bytes)
• onERC721Received(address, address, uint256, bytes)
• fallback()
• receive()

Usage

The following attack contract demonstrate a simple reentrancy attack on a improper implementation of a deposit and withdraw contract.

• ReentrancyExampleAttack

Extend the Reentrancy contract and implement the following functions:

contract Attack is Reentrancy {
    function initiateAttack() external { }
    function _executeAttack() internal override { }
    function _completeAttack() internal override { }
}

The _reentrancyCallback function in the Reentrancy template handles the callback from the vulnerable contract. Override this function to change the behavior of reentering multiple times.

/**
 * @dev Function run when target contract makes external call back to attack contract
 */
function _reentrancyCallback() incrementState internal virtual {
    console.log("Begin reentrancy stage %s", uint(reentrancyStage));
    if(reentrancyStage == State.ATTACK) {
        // Execute attack
        console.log("Execute attack");
        _executeAttack();
    } else if(reentrancyStage == State.POST_ATTACK) {
        // Already ran the attack once
        console.log("Attack completed successfully");
        _completeAttack();
    } else {
        // No state defined
    }
}