MyBB 1.8.10 Server-Side Request Forgery

`SEC Consult Vulnerability Lab Security Advisory < 20170407-0 >  
=======================================================================  
title: Server Side Request Forgery (SSRF) Vulnerability  
product: MyBB  
vulnerable version: 1.8.10  
fixed version: 1.8.11  
CVE number: CVE-2017-7566  
impact: Medium  
homepage: https://mybb.com/  
found: 2017-03-03  
by: Wan Ikram (Office Kuala Lumpur)  
Fikri Fadzil (Office Kuala Lumpur)  
Jasveer Singh (Office Kuala Lumpur)  
SEC Consult Vulnerability Lab  
  
An integrated part of SEC Consult  
Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow  
Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich  
  
https://www.sec-consult.com  
  
=======================================================================  
  
Vendor description:  
-------------------  
"With everything from forums to threads, posts to private messages, search to  
profiles, and reputation to warnings, MyBB features everything you need to run  
an efficient and captivating community. Through plugins and themes, you can  
extend MyBB's functionality to build your community exactly as you'd like it."  
  
Source: https://mybb.com/  
  
  
Business recommendation:  
------------------------  
The patch should be installed immediately if cURL functions are disabled.  
  
Furthermore, SEC Consult recommends to perform a thorough security review of  
this software.  
  
  
Vulnerability overview/description:  
-----------------------------------  
1. Server-Side Request Forgery  
An attacker is able to initiate socket connections with arbitrary systems using  
the internal network interface of the server via the web application's "Change  
Avatar" function. This vulnerability can be used to identify internal hosts and  
perform internal port scanning.  
  
  
Proof of concept:  
-----------------  
1. Server-Side Request Forgery  
This vulnerability can be exploited by an attacker with a registered account  
as low as a normal account. If the server which is hosting the web application  
disallows cURL functions, the application will use the "fsockopen" function as an  
alternative. Below is the example on how the SSRF issue can be exploited.  
  
URL : http://$DOMAIN/usercp.php  
METHOD : POST  
PAYLOAD : avatarurl=http://$IP:$PORT:80  
  
  
Vulnerable / tested versions:  
-----------------------------  
MyBB version 1.8.10 has been tested. This version was the latest version  
at the time the security vulnerability was discovered.  
  
  
Vendor contact timeline:  
------------------------  
2017-03-09: Contacting vendor through the "Private Inquiries" forum at  
https://community.mybb.com/forum-135.html  
2017-03-09: Advisory sent through the "Private Inquiries". Vendor has  
confirmed the issues. No specific date on the fix was given  
2017-03-17: Vendor confirmed the vulnerability; working on the fix  
2017-03-31: Requesting a status update.  
2017-04-04: Patch released by the vendor.  
2017-04-07: Public release of advisory.  
  
  
Solution:  
---------  
Upgrade to MyBB 1.8.11  
  
For further information see:  
https://blog.mybb.com/2017/04/04/mybb-1-8-11-merge-system-1-8-11-release/  
  
  
Workaround:  
-----------  
None  
  
  
Advisory URL:  
-------------  
https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm  
  
  
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EOF Fikri Fadzil / @2017  
  
`