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

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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


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SEC Consult Vulnerability Lab

SEC Consult
Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow
Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich

About SEC Consult Vulnerability Lab
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Vulnerability Lab supports high-quality penetration testing and the evaluation
of new offensive and defensive technologies for our customers. Hence our
customers obtain the most current information about vulnerabilities and valid
recommendation about the risk profile of new technologies.

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EOF Fikri Fadzil / @2017