Investigating and analyzing security incidents, identifying root causes, and proposing corrective actions of DCS System

 

Investigating and analyzing security incidents in DCS (Distributed Control Systems) or industrial environments requires a structured approach tailored to real-time, safety-critical systems. These investigations focus not only on the technical root cause but also on understanding how the incident impacted the control system, its operations, and long-term reliability.

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🔍 Incident Investigation & Root Cause Analysis Framework (DCS/OT Focus)

🎯 Objectives:

• Determine what happened, how it happened, and why it happened.
• Identify systemic weaknesses that allowed the incident to occur.
• Propose and implement corrective and preventive actions.

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🧭 Step-by-Step Process

Phase	Activities	Tools / Techniques
1. Incident Triage	Categorize and prioritize the incident (e.g., malware, unauthorized command, data exfiltration)	Incident classification matrix (impact + urgency)
2. Evidence Collection	Gather logs, memory, network data, system snapshots	Wireshark, controller logs, OS logs, SIEM exports
3. Timeline Reconstruction	Rebuild sequence of events leading up to and during the incident	Log correlation, system timestamps, NTP sync check
4. Technical Root Cause Analysis	Determine the exploit vector, vulnerabilities exploited, misconfigurations used	Attack path mapping, forensic imaging, reverse engineering
5. Impact Assessment	Identify affected assets, data, systems, and physical processes	Asset inventory, historian data, DCS process review
6. Human Factor Analysis	Assess if missteps by users/operators contributed (e.g., phishing, unsafe USB use)	Interviews, access audit, training review
7. Vendor/System Dependencies	Evaluate if vendor software, services, or 3rd-party maintenance introduced risks	Vendor logs, maintenance records
8. Root Cause Documentation	Use RCA methods (e.g., 5 Whys, Fishbone Diagram) to trace down systemic failure points	RCA templates, Ishikawa diagrams
9. Corrective & Preventive Actions	Recommend technical fixes, procedural changes, and policy improvements	CAPA plan, change control documents

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🧰 Tools for Analysis

Tool Type	Examples
Forensic Tools	FTK Imager, Volatility, Autopsy, Redline
Packet Analysis	Wireshark, Zeek, TCPDump
Log Analysis	Splunk, Elastic, syslog-ng, Nozomi logs
Threat Intelligence	MITRE ATT&CK for ICS, CISA ICS advisories, vendor CERTs
RCA Tools	TapRooT, 5 Whys templates, Fishbone diagrams

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📊 Example Root Cause Analysis Output

Category	Findings
Incident	Ransomware detected on Engineering Workstation (HMI)
Root Cause	Phishing email opened from dual-use (IT/OT) workstation
Contributing Factors	No email filtering, no user awareness training, no endpoint protection
Process Impact	Temporary loss of historian, operator screen lock-up
Corrective Actions	Segment IT/OT access, install endpoint AV, conduct security training
Preventive Actions	Restrict email access in OT, enforce USB policy, implement monitoring

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📁 Deliverables

Artifact	Purpose
Incident Report	Full timeline, impact, response actions
RCA Summary	Structured root cause documentation (e.g., 5 Whys)
Corrective Action Plan (CAPA)	List of short/long-term fixes with owners and deadlines
Lessons Learned Document	Organizational knowledge to avoid repeat incidents
IR Closure Report	Approval that incident was handled and closed per policy

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✅ Best Practices

• Always involve control engineers and system integrators in the investigation.
• Maintain offline backups of logs and system images before remediation.
• Regularly test incident response playbooks and RCA processes.
• Coordinate with vendors for firmware or controller-level forensic data.
• Protect evidence chain of custody for potential legal or audit use.

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Would you like a template for RCA documentation, a corrective action tracker (Excel/Word), or a sample incident report for DCS environments?