[RCESEC-2016-002] XenAPI v1.4.1 for XenForo Multiple Unauthenticated SQL Injections

RCE Security Advisory
https://www.rcesecurity.com


1. ADVISORY INFORMATION
=======================
Product:        XenAPI for XenForo
Vendor URL:     github.com/Contex/XenAPI
Type:           SQL Injection [CWE-89]
Date found:     2016-05-20
Date published: 2016-05-23
CVSSv3 Score:   7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)
CVE:            -


2. CREDITS
==========
This vulnerability was discovered and researched by Julien Ahrens from
RCE Security.


3. VERSIONS AFFECTED
====================
XenAPI for XenForo v1.4.1
older versions may be affected too but were not tested.


4. INTRODUCTION
===============
This Open Source REST API allows usage of several of XenForo's functions, 
such as authentication, user information and many other functions!

(from the vendor's homepage)


5. VULNERABILITY DETAILS
========================
The plugin "XenAPI" for XenForo offers a REST Api with different functions
to query and edit information from the XenForo database backend. Amongst 
those are "getGroup" and "getUsers", which can be called without 
authentication (default) and since the application does not properly 
validate and sanitize the "value" parameter, it is possible to inject 
arbitrary SQL commands into the XenForo backend database.

The following proof-of-concepts exploit each vulnerable REST action
and extract the hostname of the server:

https://127.0.0.1/api.php?action=getUsers&value=' UNION ALL SELECT
CONCAT(IFNULL(CAST(%40%40HOSTNAME AS CHAR)%2C0x20))%2CNULL%23

https://127.0.0.1/api.php?action=getGroup&value=' UNION ALL SELECT
NULL%2CNULL%2CNULL%2CNULL%2CNULL%2CCONCAT(IFNULL(CAST(%40%40HOSTNAME AS
CHAR)%2C0x20))%2CNULL%23


6. RISK
=======
The vulnerability allows remote attackers to read sensitive information 
from the XenForo database like usernames and passwords. Since the affected 
REST actions do not require an authentication hash, these vulnerabilities 
can be exploited by an unauthenticated attacker.


7. SOLUTION
===========
Update to the latest version v1.4.2


8. REPORT TIMELINE
==================
2016-05-20: Discovery of the vulnerability
2016-05-20: Notified vendor via contact address
2016-05-20: Vendor provides update for both issues
2016-05-21: Provided update fixes the reported issues
2016-05-21: Vendor publishes update
2016-05-23: Advisory released


9. REFERENCES
=============
https://github.com/Contex/XenAPI/commit/00a737a1fe45ffe5c5bc6bace44631ddb73f2ecf
https://xenforo.com/community/resources/xenapi-xenforo-php-rest-api.902/update?update=19336