ICS Incident Response Playbooks

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Playbooks for responding to incidents involving Programmable Logic Controllers (PLCs), Supervisory Control and Data Acquisition (SCADA) systems, and Remote Terminal Units (RTUs) provide a structured, repeatable response process. Each playbook should be tailored to the unique characteristics and operational context of these devices and systems while addressing the specific types of threats they face.

Here is an overview of what these playbooks might look like:

PLC Incident Response Playbook¶

Objective: Identify, contain, and remediate incidents affecting PLCs to prevent unauthorized control, data manipulation, or disruption of physical processes.

Key Components¶

Preparation
- Maintain an updated inventory of all PLCs, including their firmware versions, IP addresses, network segments, and connected devices.
- Regularly back up PLC configurations and firmware.
- Implement strict access controls and authentication mechanisms, such as role-based access control (RBAC).
- Ensure logging and monitoring of PLC traffic, including command and configuration changes.
- Conduct regular security training for staff on PLC threats and best practices.
Detection
- Monitor for unauthorized PLC connections or traffic patterns.
- Use Intrusion Detection Systems (IDS) and anomaly detection tools to identify unusual Modbus, Ethernet/IP, or other relevant protocol traffic.
- Look for unexpected PLC behavior, such as unscheduled reboots, changes in operating mode, or altered setpoints.
Initial Containment
- Isolate the affected PLC from the network if feasible without disrupting critical operations.
- Disable remote access to the PLC and review recent access logs to identify unauthorized actions.
- Verify the integrity of the PLC’s configuration and firmware by comparing it against a known good baseline.
Investigation
- Determine the source and nature of the incident by analyzing network traffic, PLC logs, and any connected devices.
- Check for signs of malicious activity, such as unauthorized command execution, unauthorized configuration changes, or suspicious network connections.
- Identify potential entry points, such as vulnerable protocols, weak authentication mechanisms, or compromised credentials.
Eradication and Recovery
- Remove any unauthorized software or scripts installed on the PLC.
- Revert the PLC to its last known good configuration and firmware.
- Patch or update the PLC firmware to address any known vulnerabilities.
- Reinforce access controls and network segmentation to prevent future incidents.
Post-Incident Analysis
- Conduct a root cause analysis to determine how the attack occurred and identify any weaknesses in security controls.
- Update the PLC playbook and incident response plans based on lessons learned.
- Provide training to personnel on the incident and any new procedures or best practices.

SCADA Incident Response Playbook¶

Objective: Protect the SCADA system from unauthorized access, data breaches, or attacks that could impact the overall control and monitoring of industrial processes.

Key Components¶

Preparation
- Maintain a complete asset inventory of SCADA components, including Human-Machine Interfaces (HMIs), servers, data historians, and communication channels.
- Implement network segmentation and firewall rules to isolate SCADA networks from corporate IT networks and the internet.
- Regularly update and patch SCADA software and systems, while considering operational impact.
- Enable comprehensive logging and monitoring of SCADA activities, including user access, command execution, and configuration changes.
- Develop incident response procedures that account for the unique needs of SCADA environments, such as real-time operational impacts.
Detection
- Monitor SCADA systems for unusual network traffic, unauthorized access attempts, or abnormal command sequences.
- Use specialized SCADA-aware IDS/IPS solutions to detect known exploits or anomalous behavior patterns.
- Look for signs of physical compromise or tampering with SCADA equipment or control stations.
Initial Containment
- Restrict access to SCADA systems from suspected compromised user accounts or IP addresses.
- Block malicious traffic or connections identified through monitoring tools.
- Coordinate with field operators to ensure that containment actions do not disrupt critical operations.
Investigation
- Analyze SCADA logs, IDS/IPS alerts, and network traffic to determine the scope and nature of the incident.
- Identify compromised components, user accounts, or communication channels.
- Determine the attacker’s objectives, such as manipulating process data, exfiltrating sensitive information, or disrupting control functions.
Eradication and Recovery:
- Remove any malware or unauthorized applications from SCADA servers and endpoints.
- Restore affected SCADA components from trusted backups.
- Validate the integrity of SCADA data and ensure that all settings and configurations match the established baseline.
- Update software, configurations, and security controls to address any vulnerabilities exploited during the incident.
Post-Incident Analysis:
- Review the effectiveness of detection, containment, and recovery actions.
- Document the incident timeline, findings, and any gaps in current security practices.
- Update the SCADA incident response playbook and provide training to operators and security teams.

RTU Incident Response Playbook¶

Objective: Protect RTUs from unauthorized access, command manipulation, or disruption of their communication with control centers.

Key Components¶

Preparation
- Maintain an accurate inventory of all RTUs, including their firmware versions, communication protocols, and network locations.
- Regularly update RTU firmware and software to address known vulnerabilities.
- Implement network segmentation to isolate RTU traffic from corporate IT networks and unauthorized devices.
- Enable secure communication channels (e.g., VPNs, encrypted protocols) between RTUs and control centers.
- Develop contingency plans for maintaining control and monitoring capabilities if RTUs are compromised or isolated.
Detection
- Monitor for unauthorized access attempts, unexpected configuration changes, or unusual command traffic to RTUs.
- Use anomaly detection tools to identify deviations from normal communication patterns, such as unexpected data flows or command sequences.
- Check for signs of interference or jamming of wireless communication channels used by RTUs.
Initial Containment
- Isolate compromised RTUs by disabling communication channels or blocking network traffic from suspicious IP addresses.
- Verify the integrity of RTU configurations and data by comparing them against known good baselines.
- Coordinate with field technicians or operators to inspect RTUs for signs of tampering or physical compromise.
Investigation
- Analyze RTU communication logs, network traffic, and configuration files to determine the scope and nature of the incident.
- Identify any unauthorized commands sent to RTUs, such as those that could change setpoints, control parameters, or operational modes.
- Determine the source of the attack, whether from a remote attacker, an insider, or a compromised third-party device.
Eradication and Recovery
- Restore compromised RTUs to their last known good state using trusted backups or pre-configured settings.
- Remove any unauthorized software or firmware from RTUs and validate their integrity.
- Re-establish secure communication channels between RTUs and control centers.
- Patch or update RTUs to prevent exploitation of vulnerabilities used in the attack.
Post-Incident Analysis
- Conduct a debrief with all relevant teams to identify lessons learned and improve incident response capabilities.
- Update the RTU incident response playbook to incorporate new findings and procedures.
- Provide training to field technicians and operators on recognizing and responding to RTU-related threats.

Common Elements Across All Playbooks¶

Communication Plan: Establish clear communication protocols for internal teams (security, operations, management) and external partners (vendors, regulators).
Documentation: Document each step of the incident response process, including detection, containment, investigation, and recovery actions.
Continuous Improvement: Regularly review and update playbooks based on lessons learned, changes in technology, and emerging threats.
Coordination with ICS Operators: Ensure close coordination with ICS operators to minimize operational impact while responding to incidents.