IEEE C37.118 Synchrophasor Data in Power Systems
IEEE C37.118 is a standard that defines a communication protocol for transmitting synchrophasor data in power systems. It's essentially the "language" that Phasor Measurement Units (PMUs) and Phasor Data Concentrators (PDCs) use to talk to each other, enabling real-time monitoring and control of the power grid.
Synchrophasors: Synchronized phasor measurements of voltage and current in the power system, providing a precise and real-time snapshot of the grid's state. Think of them as synchronized "heartbeats" of the electrical grid. Real-Time Grid Monitoring: Synchrophasor data is crucial for: State Estimation: Understanding the current state of the power system, including voltage levels, power flows, and stability. Fault Detection and Analysis: Quickly identifying and locating faults (short circuits, line outages) to prevent cascading failures and blackouts. Wide-Area Monitoring and Control: Coordinating control actions across vast geographical areas to improve grid stability and reliability.=
IEEE C37.118 is the essential communication protocol that enables real-time monitoring and control of power grids using synchrophasor technology. While the standard itself provides a framework for efficient data transmission, its security aspects require careful attention and the implementation of robust safeguards to mitigate the growing threat of cyberattacks targeting critical infrastructure.
STRIDE ANALYSIS
ASSETS
- Synchrophasor Data: This includes synchronized phasor measurements, frequency, and rate of change of frequency (ROCOF) data.
- Phasor Measurement Units (PMUs): Devices that produce synchronized phasor, frequency, and ROCOF estimates from voltage and/or current signals.
- Data Concentrators (DCs): Devices that combine data from several PMUs.
- Time Synchronization Signals: GPS or other time synchronization signals ensuring accurate time-stamping of measurements.
- Communication Channels: Channels used for transmitting synchrophasor data between PMUs, DCs, and control centers.
TRUST BOUNDARIES
- Between PMUs and Data Concentrators: Data from PMUs is transmitted to data concentrators.
- Between Data Concentrators and Control Centers: Data concentrators transmit aggregated data to control centers.
- Time Synchronization Boundary: Ensuring the integrity and accuracy of time synchronization signals from GPS or other sources to PMUs.
DATA FLOWS
- Voltage and Current Signals: The PMU receives voltage and current signals from the power system through sensors and analog-to-digital converters.
- Time Synchronization Signal: The PMU receives time synchronization signals (e.g., GPS, IRIG-B) to establish accurate time references for synchrophasor measurements.
- Synchrophasor Data: PMU transmits synchrophasor measurements (voltage, current, frequency, ROCOF) to external systems.
- Control Commands: External systems may send control commands (e.g., setting PMU configuration) to the PMU.
- Communication Network Data: The PMU exchanges data with the communication network.
THREAT MODEL
| THREAT ID | COMPONENT NAME | THREAT NAME | STRIDE CATEGORY | WHY APPLICABLE | HOW MITIGATED | MITIGATION | LIKELIHOOD EXPLANATION | IMPACT EXPLANATION | RISK SEVERITY |
|---|---|---|---|---|---|---|---|---|---|
| 0001 | PMU | Spoofing of Time Synchronization Signal | Spoofing | Time synchronization is critical for accurate phasor measurements. | Not mitigated in design. | Use authenticated time sources and secure communication channels for time synchronization signals. | Medium - GPS signals can be spoofed but require proximity or sophisticated equipment. | High - Incorrect time synchronization can lead to inaccurate measurements and system instability. | High |
| 0002 | Data Concentrator | Tampering with Synchrophasor Data | Tampering | Data integrity is crucial for accurate monitoring and control. | Not mitigated in design. | Implement end-to-end encryption and integrity checks for data transmission. | Medium - Requires access to communication channels but can be done remotely. | High - Tampered data can lead to incorrect decisions and potential system failures. | High |
| 0003 | Communication Channel | Denial of Service (DoS) Attack on Data Transmission | Denial of Service | Continuous data flow is essential for real-time monitoring and control. | Not mitigated in design. | Implement network redundancy and DoS protection mechanisms. | Medium - DoS attacks are common but can be mitigated with proper network design. | High - Loss of data flow can lead to loss of situational awareness and delayed response to system events. | High |
| 0004 | PMU | Unauthorized Access to PMU Configuration | Information Disclosure | Unauthorized access can lead to configuration changes affecting measurement accuracy. | Not mitigated in design. | Implement strong authentication and access control mechanisms for PMU configuration interfaces. | Medium - Requires access to PMU interfaces but can be done remotely if not secured. | High - Incorrect configuration can lead to inaccurate measurements and system instability. | High |
| 0005 | Control Center | Exfiltration of Synchrophasor Data by Insider Threats | Information Disclosure | Sensitive data can be misused if accessed by unauthorized personnel. | Not mitigated in design. | Implement strict access controls, monitoring, and auditing of user activities in control centers. | Low - Insider threats are less common but possible. | High - Exfiltrated data can be used for malicious purposes or competitive advantage. | Medium |
| 0006 | Data Concentrator | Injection of Malicious Data into Aggregated Streams | Tampering | Malicious data can disrupt monitoring and control functions. | Not mitigated in design. | Implement data validation and anomaly detection mechanisms at data concentrators. | Medium - Requires access to data concentrators but can be done remotely if not secured. | High - Malicious data can lead to incorrect decisions and potential system failures. | High |
| 0007 | Communication Channel | Eavesdropping on Synchrophasor Data Transmission | Information Disclosure | Sensitive data can be intercepted during transmission. | Not mitigated in design. | Implement end-to-end encryption for all data transmissions. | Medium - Requires access to communication channels but can be done remotely. | Medium - Intercepted data can be used for malicious purposes or competitive advantage. | Medium |
| 0008 | PMU | Manipulation of Measurement Algorithms by Malware | Tampering | Malware can alter measurement algorithms leading to incorrect data. | Not mitigated in design. | Implement robust cybersecurity measures including malware detection and prevention on PMUs. | Low - Requires sophisticated attack but possible with advanced persistent threats (APTs). | High - Altered measurements can lead to incorrect decisions and potential system failures. | Medium |
QUESTIONS & ASSUMPTIONS
- Assumption: The PMU is designed and implemented with secure coding practices to minimize software vulnerabilities.
- Assumption: The communication network is designed and maintained with security considerations, including firewalls, intrusion detection systems, and encryption.
- Assumption: External systems (e.g., data concentrators, control centers) have robust security measures in place to prevent unauthorized access.
- Question: What specific security measures are in place for the PMU's firmware and software updates?
- Question: What are the network segmentation strategies implemented to protect the PMU from external attacks?
- Question: What are the recovery procedures in case of a PMU failure or denial-of-service attack?
- Question: Are there any plans to implement authentication mechanisms for data transmitted between the PMU and external systems?
Note: Threats like "Replay Attacks" and "Man-in-the-Middle Attacks" are not included in the table above because they are inherently addressed by the implementation of data encryption and digital signatures. These security measures are assumed to be implemented in the communication protocols and data transfer mechanisms.