nadir-akhtar

Capture the Ether Writeup

This writeup is a runthrough of challenges at https://capturetheether.com/challenges/ built on the Ropsten testnet. I will go through each problem in four steps:

1. The intention of the contract
2. The flawed assumption
3. The process of exploiting the vulnerability
4. The potential patches

I'll provide examples of the code I wrote as needed. To save time, we'll skip into the Lotteries section, starting with Guess the secret number, as that's the first problem which truly required some thought.

paulgambill

/**
 * Retrieves all the rows in the active spreadsheet that contain data and logs the
 * values for each row.
 * For more information on using the Spreadsheet API, see
 * https://developers.google.com/apps-script/service_spreadsheet
 */
function readRows() {
  var sheet = SpreadsheetApp.getActiveSheet();
  var rows = sheet.getDataRange();
  var numRows = rows.getNumRows();