Calculate SHA256 hash from error message in "Parameter Tampering" > "Bypass Client Side JavaScript Validation" using the browser console

webgoat.js

// You need to type in console `allow pasting` and hit enter. 
// This is one time thing and will enable the pasting functionality.

// If this code doesn't work on your browser, take the output from:
// document.querySelector("#message.info").innerText.trim()
// and use an online tool like https://emn178.github.io/online-tools/sha256.html
// to get the SHA256 digest
 
async function sha256(rawData) {
  const data = typeof rawData === 'object' ? JSON.stringify(rawData) : String(rawData);

  const msgBuffer = new TextEncoder().encode(data);
  const hashBuffer = await crypto.subtle.digest('SHA-256', msgBuffer);
  const hashArray = Array.from(new Uint8Array(hashBuffer));
  return hashArray.map(b => b.toString(16).padStart(2, '0')).join('');
}

sha256(document.querySelector("#message.info").innerText.trim()).then((hash) => { console.log(hash); });