Traditionally, automation systems and protocols have been designed as not completely secure. As for reliability, you may agree that it would be a pity if the motor or door gets stuck because of incorrect access rights to a file or an expired SSL certificate.
Universal Controller, Logic Manager, SCADA Final Aggregator subsystems, as well as their interfaces, openly exchange API keys. If you do not use SSL, these keys can easily be caught. That is why only a separate secure network should be used to connect the controllers in the working configuration. Alternatively, you should install as many controllers as possible on the same server. Built-in web interfaces of the individual subsystems are called Emergency Interfaces. Therefore, they can only be used during primary setup, testing as well as in case of emergency but not on a regular basis.
All programs and extensions which use API calls should be connected at least via SSL or, ideally, in a separate secure network.
If you use secure networks or separate VLANs, it is not recommended to use SSL for API calls to avoid making setup complex and increasing load on your equipment.
The recommended enterprise configuration of the system is represented in the following scheme:
- Public network external network (company’s local network); applications working in a public network (usually SCADA interfaces), should be protected from unauthorized access as much as possible: they should use SSL and complex passwords and be regularly updated with the latest security patches.
- Supervisory network network accessed by authorized company employees only; it includes MQTT (event server), PLC (Logic Manager), custom automation applications and “public” interfaces of Universal Controller subsystems. The security policies are minimal. They are used not as means for protection against hacking, but rather for eliminating the possibility of component malfunction. Passwords/keys can be simple, pure HTTP without SSL can be used in order to reduce the load and avoid system failure because of incorrect certificates.
- Direct control network network in which only item management controllers operate, e.g. “productional” Universal Controller interfaces, TCP/IP-controlled relays, network sensor controllers etc.
In many setups, you may combine Supervisory network and Direct control network into a single network. As for security, this decision is not that bad, if the primary goal to divide these networks is comfortable maintenance.
Primary EVA interface is itself rather secure. Still, when connecting via insecure networks, especially via external Internet connection, it is highly recommended to:
- use frontend (NGINX, Apache)
- use SSL only (if frontend is present - use it for SSL processing)
- use firewall and forward only one port to the server with an interface
It is strongly recommended to access enterprise configurations with VPN only.
It is not recommended to keep debugging mode enabled in the production system, because some important data may be recorded in the log files.
Should I run it as root?
- Universal Controller is designed to be run on virtual machines, microcomputers, and embedded systems. If server directly controls connected devices, you should run it as root in order to avoid any device access errors. UC security bottleneck (when working under root) - API and UC EI interface. However, you should use API in Supervisory network only and UC EI interface should be turned off and used only in case of emergency.
- Logic Manager does not require direct access to the equipment, that is why it can be run as root on the selected system (if really required) or as a restricted user on the common-purpose servers. If Logic Manager API and interface are available only in Supervisory network, this issue is not critical for security.
- All external interfaces of the system, including SCADA Final Aggregator, should be run only under restricted users and protected with additional frontend and/or firewall.
X-Real-IP HTTP header
HTTP API uses X-Real-IP header variable to determine real IP address of client when working behind frontend. This can be used by attacker to compromise real IP address and bypass hosts_allow/hosts_assign key access control lists. Frontend should always clear X-Real-IP header variable and set it to the real ip of remote client.
X-Real-IP feature is disabled by default. To enable it, set param x_real_ip=yes in webapi section of controller configuration file.
Universal Controller API keys
- The key should contain at least 14 characters, including numbers, lowercase, and uppercase letters. Default keys generated during easy setup are random sha256 64-byte length hashes, which’s more than enough for security unless they’re transferred between controllers in an insecure network and sniffed.
- As far as day-to-day tasks are concerned, it is recommended to use API key masterkey (as well as all keys with master rights) only locally or for the system configuration/emergency situations.
- For the use of UC EI it is recommended to create operator key with groups = #, sysfunc = yes permissions.
- When connecting to Logic Manager and SCADA Final Aggregator it is recommended to create a separate key with rights for certain item groups, sysfunc = no, optionally allow = cmd.
- All external applications should have their own keys with restricted access rights to the required functions and items only.
- After installation, make sure that etc/uc_apikeys.ini file has 0600 permissions (and owned by the user you are running the controller under)
Logic Manager API keys
- After the initial configuration is complete, it is recommended to connect external applications only via keys with certain rights. Master key should not be used.
SCADA Final Aggregator interfaces
- If interface is available from within a public network, you should always use frontend with additional authentication
- Private data should be stored on SFA PVT server or protected in other way.
Common API security recommendations
If server is present in several VLANs, make sure that API listens only on Supervisory network address. If you do not use UDP API or SNMP traps in Universal Controller, disable them in the controller configuration. Do not enable the remote file control function unless it’s necessary for external apps.
Every component may be started in a “developer mode”: if enabled, all data, including API keys, is openly written in the log file. That is why we do not advise you to enable it unless you are our developer or integrator. Still, as far as the whole system code is open, you can try to enable it on your own responsibility. Never enable developer mode on the working system and avoid enabling debug mode as well.
If you contacted the product vendor or integrator who explained to you how to make a system “dump”, you should delete it from the system immediately after the file is no longer required. “dump” contains plenty of confidential data, including all API KEYS. Never give dump files to unauthorized persons! This is the same as giving away all configuration files, including the keys.
Dump file should be sent only via secure channels or in an encrypted form.