Authentication Issues between entities during protocol message exchange in SCADA Systems. Manuel Humberto Santander Peláez

Transcription

1 Authentication Issues between entities during protocol message exchange in SCADA Systems Manuel Humberto Santander Peláez

2 Agenda Introduction SCADA protocols Authentication Risks Remediation

3 SCADA Supervisory Control and Data Acquisition Platform used to monitor and control all the variables of a real-time process Several variables to monitor Pressure inside a water tube used for distribution Flow speed of oil Amount of electric charge passing inside an electricity transmission line

4 Components of SCADA platform

5 Components of SCADA platform (2) Remote Terminal Unit (RTU): This is a communication device within the SCADA system and is located at the remote substation. The RTU gathers data from field devices in memory until the MTU request that information. It also process orders from the SCADA like switch off a transmission line It process the commands ordered by the HMI to the field devices

6 Components of SCADA platform (3) Data Acquisition System (DAS): Gathers information from the MTU Generates and store alerts that needs attention from the operator because it can cause impact on the system Master Terminal Unit (MTU): The MTU is defined as the heart of a SCADA system and is located at the main monitoring center.

7 Components of SCADA platform (4) Master Terminal Unit (MTU): MTU initiates communication with remote units and interfaces with the DAS and the HMI. Human Machine Interface (HMI): Interface where the operator logs on to monitor the variables of the system. Gathers information from the DAS Sends commands to the MTU and wait for response

8 Electrical process Three big steps Generation Transmission Distribution Energy is created using any of the following methods Thermoelectrical plans Nuclear plants Hydro electrical plants

9 Electrical process (2) SCADA platform is vital to perform the following when generation takes place: Ensure turbines are not having revolutions more than supported Generators are not working overloaded Energy being generated matches the amount of energy that the transmission line can handle

10 Electrical process (3) Transmission Energy being generated needs to be distributed to reach the final users 115 KV is the power used to transmit in the wire lines Final destination are the substations that handles energy of a specific amount of instalations Large number of blocks in a city

11 Electrical process (4) SCADA platform is vital to perform the following when transmission takes place: Monitoring of voltage in transmission lines looking for high amount of electricity flowing None of them can get overloaded because protections get activated and a blackout appears in all the installations that are controlled by the affected substations

12 Electrical process (5) Distribution Energy being generated needs to be distributed to reach the final users 115 KV is the power used to transmit in the wire lines Final destination are the substations that handles energy of a specific amount of instalations Large number of blocks in a city

13 Electrical process (6) SCADA platform is vital to perform the following when distribution takes place: Monitoring of voltage in transmission lines looking for high amount of electricity flowing Monitoring of voltage in user meters looking for high amount of electricity flowing

14 Agenda Introduction SCADA Protocols Authentication Risks Remediation

15 SCADA Protocols Modbus IEC 104 DNP3

16 Modbus Source: Practical Industrial Data Communications

17 Modbus (2) Client/server protocol which operates in a request/response mode Three variants: Modbus serial RS-232/RS-485: Implemented on serial networks Modbus TCP: Used for SCADA platforms where delay is not an issue (Water supply) Modbus UDP: Used for SCADA platforms where delay is a big issue (Energy)

18 Modbus (3) Source: Practical Industrial Data Communications

19 Modbus (4) Modbus protocol structure Address field: Request frames: Address of the device being targeted by the request Response frame: Address of the device responding to request

20 Modbus (5) Modbus protocol structure Function field Function requested by the HMI to be performed by the field devices In response packets, when the function performed is succeeded, the field device echoes it. If some exception occurred, the most significant bit of the field is set to 1

21 Modbus (6) Data Access Bit access 16-bit access Function Function Name Type of access Code Physical Discrete Inputs Read Discrete Inputs 2 File Record Access Internal Bits or Physical Coils Read Coils 1 Write Single Coil 5 Write Multiple Coils 15 Physical Input Registers Read Input Register 4 Read Holding Registers 3 Write Single Register 6 Internal Registers or Physical Output Registers Write Multiple Registers 16 Read/Write Multiple Registers 23 Mask Write Register 22 Read FIFO Queue 24 Read File Record 20 Write File Record 21

22 Modbus (7) Type of access Diagnostics Other Function Name Function Code Read Exception Status 7 Diagnostic 8 Get Com Event Counter 11 Get Com Event Log 12 Report Slave ID 17 Read Device Identification 43 Encapsulated Interface Transport 43

23 Modbus (8) Modbus protocol structure Data field In request paquets, contains the information required to perform the specific function In response packets, contains the information requested by the HMI

24 Modbus (9) Modbus protocol structure Error check Field CRC-16 on the message frame If packet has errors, the field device does not process it Timeout is assumed, so the master sends again the packet to attempt again a function execution

25 IEC 104 Standard for power system monitoring, control and communications for telecontrol and teleprotection for electric power systems Completely compatible with: IEC : Transmission frame formats for standard IEC : Basic application functions

26 IEC 104 (2) It has the following features: Supports master initiated messages and master/slave initiated messages Facility for time sinchronization Possibility of classifying data being transmitted into 16 different groups to get the data according to the group Cyclic and spontaneous data updating schemes are provided.

27 IEC 104 (3) Source: Practical Industrial Data Communications

30 IEC 104 (6) Link level Link service class Function Explanation S1 SEND / NO REPLY Transmit message. No ACK or answer required S2 SEND / CONFIRM Transmit message. ACK required Transmit message. ACK and answer S3 REQUEST / RESPOND required

32 IEC 104 (8) Control field for unbalanced transmissions Source: Practical Industrial Data Communications

33 IEC 104 (8) Control field for balanced transmissions Source: Practical Industrial Data Communications

34 DNP3 Set of communication protocols used between components of a SCADA system Used for communications between RTU and the IED (field devices) Implements the communication levels established by the enhance performance architecture (EPA)

35 DNP3 (2) Enhance performance architecture (EPA) Source: Practical Industrial Data Communications

36 DNP3 (3) Message exchange Source: Practical Industrial Data Communications

37 DNP3 (4) Frame format Source: Practical Industrial Data Communications

38 DNP3 (5) Control Byte Source: Practical Industrial Data Communications

40 Network technologies in SCADA Systems Many SCADA networks still use RS232/RS485 bus to communicate all components But also because of the need to access data in a fast way, we also have serial-toip gateways to access serial RTU and IED Lots of hybrid SCADA networks having serial and IP components Vulnerable from outsiders at the corporate network

41 Lack of authentication in application protocol The SCADA protocols does not perform bi-directional authentication to ensure that all parties are trusted Only commands are sent Data is sent to the IP address configured as master All the IP spoofing vulnerabilities works on any MTU or Field device Any command can be sent

42 Lack of confidentiality in application protocol The SCADA protocols does not perform any encryption to protect the information Modbus, IEC 101/104 and DNP3 transmissions can be checked by any attacker Man-in-the-middle can be performed on the network MTU traffic can be intercepted and then redirected to any IED with any desired change No way to know if traffic is trusted

43 What could be done? Let s see how a master station puts the current timestamp on an IED Let s see how the attacker changes it Can issue writable commands and reading commands DEMO TIME!

45 What you cannot do with SCADA Protocol delay is usually a BIG issue in SCADA Water supply and Oil SCADA tolerates big delays because it does not have consequences in the process Power SCADA is critical. A delay higher than 5 miliseconds could end in a massive blackout because of failure to open a breaker in a substation Be careful on what you do to protect your SCADA

46 SCADA Network Design

47 Monitor your network SCADA traffic baseline is mandatory You need to know what applications are doing transit inside your network Inside SCADA protocols you monitor applications that gives you information on the industrial process being controlled Unauthorized applications could indicate a breach trying to perform operations or gather information on IED

48 Monitor your network (2) Use Network Intrusion Prevention System You definitely can use conventional IPS if they are fast enough to avoid delays in your network Not all of them support SCADA protocols If you have snort, you can write rules for Modbus and DNP3. Otherwise, you need to write your own rules Industrial Defender Solution works pretty good as it includes lots of SCADA signatures

49 Control unauthorized changes to Master Terminal Unit SCADA platforms are designed to last from 10 to 20 years Too many technology changes happens in that time Lots of security issues to deal with Need a solution to avoid any changes inside computers, as intrusions perform changes in filesystem, configurations and system process

50 Control unauthorized changes to Master Terminal Unit (2) SCADA platforms are designed to last from 10 to 20 years Too many technology changes happens in that time Lots of security issues to deal with Need a solution to avoid any changes inside computers, as intrusions perform changes in filesystem, configurations and system process

51 Control unauthorized changes to Master Terminal Unit (3) Control any changes inside your SCADA servers Mcafee Integrity control works pretty good Defines what can be changed by who Lots of custom logs to choose from Can send events to any SIEM configured in the Network

52 Monitor attacks to Master Unit Host IPS is definitely needed as any attack could change the integrity and stability of a process Availability is critical to a SCADA system and cannot be altered Conventional Host IPS performs extensive use of CPU and can affect performance inside SCADA

53 Monitor attacks to Master Unit (2) Industrial Defender Host IPS works pretty good Works seamless with Siemens Spectrum Platform Does not load the machine or needs extensive bandwith to perform its checks Central console to perform operations inside the platform

54 Questions? Comments? Manuel Humberto Santander Peláez / manuel@santander.name