AUDITING SCADA SYSTEMS
Introduction
SCADA (supervisory control and data acquisition) is a system operating with coded signals over communication channels so as to provide control of remote equipment (using typically one communication channel per remote station) en.wikipedia.org/wiki/SCADA
Industrial control systems (ICS) are computer-based systems that monitor and control industrial processes that exist in the physical world. SCADA systems historically distinguish themselves from ICS systems by being large-scale processes that can include multiple sites, and large distances. SCADA can be considered class of ICS.
Originally, SCADA systems were not connected to the Internet. Security was traditionally not an issue in SCADA systems. However the same is not true now.
Where is SCADA used?
Electric power generation, transmission and distribution
Water and Sewage network systems
Environment and facility monitoring and management
Transportation networks
Manufacturing processes
Functions of SCADA
DATA ACQUSITION- Furnishes status information & measures to operator
CONTROL - Allows the operator to control the devices e.g. circuit breakers, transformers, tap changer etc from a remote centralised location.
DATA PROCESSING - Includes data quality & integrity check, limit check, analog value processing etc.
TAGGING - Operator can identifies any specific device & subjects to specific operating restrictions to prevent from unauthorized operation
ALARMS - Alerts the operator of unplanned events & undesirable operating conditions in the order their severity & criticality
LOGGING- Logs all operator entries, alarms &selected entries
TRENDING- Plots measurements on selected scale to give information on the trends e.g. one minute, one hour etc.
HISTORICAL REPORTING - To save & analyze the historical data for reporting, typically for a period of 2 or more years & to archive.
SCADA Components and Subsystems
SCADA has following components:
1. Operating equipment: pumps, valves, conveyors, and substation breakers that can be controlled by energizing actuators or relays.
2. Local processors: communicate with the site’s instruments and operating equipment. This includes the Programmable Logic Controller (PLC), Remote Terminal Unit (RTU), Intelligent Electronic Device (IED), and Process Automation Controller (PAC). A single local processor may be responsible for dozens of inputs from instruments and outputs to operating equipment.
3. Instruments: in the field or in a facility that sense conditions such as pH, temperature, pressure, power level, and flow rate.
4. Short-range communications: between local processors, instruments, and operating equipment. These relatively short cables or wireless connections carry analog and discrete signals using electrical characteristics such as voltage and current, or using other established industrial communications protocols.
5. Long-range communications: between local processors and host computers. This communication typically covers miles using methods such as leased phone lines, satellite, microwave, frame relay, and cellular packet data.
6. Host computers Human–Machine Interface or HMI: act as the central point of monitoring and control. The host computer is where a human operator can supervise the process, as well as receive alarms, review data, and exercise control.
Sub Systems
• Supervisory system
• HMI
• RTU
• PLC
• Communication Interface
• SCADA programming
SCADA vendors
Some SCADA vendors are Asea Brown Boveri(ABB), Siemens, Alstom ESCA, Telegyr Systems, Advanced Control Systems(ACS), Harris and Bailey.
SCADA protocols
SCADA protocols are communications standards to pass control information on industrial networks. There are many of these protocols but prominent ones are MODBUS, DNP3, EtherNET/IP, PROFIBUS, IEC 61850 and Foundation Fieldbus. The choice of protocol is based on operating requirements, industry preference, vendor and the design of the system. In an oil refinery an operator workstation might use the MODBUS/TCP protocol to communicate with a control device such as a Programmable Logic Controller (PLC). Alternatively, in power utility’s SCADA system, a master located in a central facility could use the DNP3 protocol to query and control slave Remote Terminal Units (RTU) distributed in remote sub-stations. Some other protocols are: ICCP, ZigBee, C37.118, and C12.22
Known Issues
1. In a SCADA system, the programmable logic controllers (PLCs) are directly connected to infield sensors that provide data to control critical components (e.g. Centrifugal or turbines). Often the default passwords are hard-coded into Ethernet cards the systems use. Those cards funnel commands into devices, allowing administrators to remotely log into the machinery. Hard-coded passwords are a common weakness built into many industrial control systems, including some S7 series of PLCs from Siemens. Hardcoded or saved passwords are also found in windows registry of various host machines. PLCs and RTUs are web enabled for remote access and this creates a window of opportunity for attackers.
2. Lack of Authentication and medium control in SCADA systems is another major issue. Investigation of past SCADA incidents demonstrated that mobile storage mediums are the main vectors used to infect control systems, despite that host networks being isolated from the Internet. Establishing strong controls on every medium used could prevent serious incidents. Strong authentication must be implemented to ensure secure communication, and to allow personnel to access main functionalities provided by systems. The administration console for any network appliance must be protected. Wireless and wired connections to the SCADA network and remote sites must be properly defended.
Steps to perform an audit
1. Identify all connections to SCADA networks. Evaluate security of connections. Identify systems that serve critical functions.
2. Conduct VA of Network Connectivity by mapping of all networked assets and the digital communication links that connect them
3. Check for default settings and configurations of all systems
4. Check for unnecessary services
5. Check if security features provided by device and system vendors are effectively activated.
6. Check authentication and medium control.
7. Check for proper network segregations.
8. Check internal and external intrusion detection systems
9. Check if 24-hour-a-day incident monitoring takes place
10. Perform technical audits of SCADA devices and networks, and any other connected networks, to identify security concerns
11. Conduct physical security surveys and assess all remote sites connected to the SCADA network to evaluate their security
12. Identify and evaluate possible attack scenarios
13. Check if cyber security roles, responsibilities, and authorities for managers, system administrators, and users have been defined.
14. Check for ongoing risk management process
15. Check for configuration management processes
16. Scrutinise routine self-assessments reports
17. Check for system backups and disaster recovery plans and BCP
18. Check for availability of policies
19. Interview all key personnel
Tools
SamuraiSTFU, plcscan, modscan, metasploit, Nessus, nmap, wireshark, tcpdump, modlib(scapy extension), Bus-pirate, CERT NetSA Security Suite, NetWitness, Lancope, Arbor, 21CT, Checkmarx, Contrast Security, Burp Suite Professional, NTOSpider, Netsparker, Appscan, sqlmap, Zulu, GPF/EFS, PFF, ImmDbg, Sulley, gdb, MSF, RTL-SDR/HackRF plus GNURadio/RFCat, binwalk, IDA Pro etc etc
https://www.thalesgroup.com/sites/default/files/asset/document/thales-cyber-security-for-scada-systems.pdf
http://resources.infosecinstitute.com/improving-scada-system-security/
