# Canvas
This challenge was a lot of fun for me. We have the source of a webpage.
In the index.html we can see that login.js is called:
```javascript
canvas
Canvas login
```
The login.js was a very obfuscated javascript:
I used jq to beautify the code, renamed variables and decoded strings etc. until I found an interesting function and array that I thought was likely the flag:
```javascript
function validate() {
var _0x4d1a17 = _0x20fe,
_0x32b344 = document['getElementById']('username')['value'],
_0x5997a2 = document[_0x4d1a17('0xd')]('password')[_0x4d1a17('0x0')];
if (_0x32b344 == _0x4d1a17('0x12') && _0x5997a2 == _0x4d1a17('0x12')) return alert(_0x4d1a17('0x9')), window['location'] = 'dashboard.html', ![];
else {
attempt--, alert(_0x4d1a17('0x2') + attempt + _0x4d1a17('0x15'));
if (attempt == 0x0) return document[_0x4d1a17('0xd')](_0x4d1a17('0xb'))['disabled'] = !![], document[_0x4d1a17('0xd')]('password')[_0x4d1a17('0x10')] = !![], document[_0x4d1a17('0xd')]('submit')[_0x4d1a17('0x10')] = !![], ![];
}
}
var res = String['fromCharCode'](0x48, 0x54, 0x42, 0x7b, 0x57, 0x33, 0x4c, 0x63, 0x30, 0x6d, 0x33, 0x5f, 0x37, 0x30, 0x5f, 0x4a, 0x34, 0x56, 0x34, 0x35, 0x43, 0x52, 0x31, 0x70, 0x37, 0x5f, 0x64, 0x33, 0x30, 0x62, 0x46, 0x75, 0x35, 0x43, 0x34, 0x37, 0x31, 0x30, 0x4e, 0x7d, 0xa);
```
Decoding the 'res' array, I got the flag.
---
# Agent Instructions: Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://shibudocs.gitbook.io/htb-writeups/challenges/canvas.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.