OT Network Segmentation: A Practical Guide for Security Teams
Digital Forensics and Incident Response (DFIR) is the discipline that combines the technical investigation of cyber incidents with the structured process of containing threats and recovering operations. For CISOs, understanding DFIR capabilities — and ensuring your organisation has access to them — is essential for managing the aftermath of a breach effectively, meeting legal and regulatory obligations, and continuously improving your security programme.
Digital Forensics vs Incident Response: Understanding the Relationship
Digital forensics focuses on the collection, preservation, and analysis of digital evidence — answering the questions of what happened, how, when, and who was responsible. Incident response focuses on containing and eradicating threats and restoring normal operations. In practice these disciplines are deeply intertwined: you cannot effectively contain a threat without understanding what it is, and you cannot conduct meaningful forensic analysis of a live incident without containing the threat.
Core DFIR Capabilities
Evidence Collection and Preservation
Forensic evidence must be collected and preserved in ways that maintain its integrity for potential legal proceedings. This requires chain of custody documentation, forensic imaging of affected systems (bit-for-bit copies), volatile data collection (memory, running processes, network connections) before systems are powered down, and log preservation from SIEMs, cloud platforms, and network infrastructure.
Malware Analysis
Understanding the malware used in an attack — its capabilities, persistence mechanisms, command and control infrastructure, and lateral movement techniques — is essential for complete eradication and for attributing the attack to a known threat actor. Static analysis examines malware without executing it; dynamic analysis observes malware behaviour in a controlled sandbox environment.
Network Forensics
Network forensics analyses captured traffic and flow data to reconstruct attacker activity — identifying initial access, lateral movement, data staging, and exfiltration. Full packet capture (PCAP) data is invaluable but storage-intensive; network flow data provides a lower-fidelity but more practical alternative for most environments.
Cloud Forensics
As organisations migrate to cloud environments, forensic investigation increasingly involves cloud platforms. Cloud forensics presents unique challenges: evidence is held by third-party providers, traditional disk imaging may be impossible, and volatile evidence (logs, snapshots) may be overwritten or deleted quickly. Cloud-native forensic capabilities — AWS CloudTrail, Azure Monitor, GCP Audit Logs — are essential and must be enabled before you need them.
Building DFIR Capability
Most organisations cannot justify maintaining a full in-house DFIR capability. The practical approach for most CISOs is a hybrid model: maintain core internal capabilities for initial triage and common incident types, and retain external DFIR specialists for complex investigations, surge capacity, and specialist skills (malware reverse engineering, OT forensics, cloud forensics).
When selecting an external DFIR retainer, evaluate: response SLAs (time to mobilise), geographic coverage, specialist capabilities (OT, cloud, specific industry), relationship with law enforcement, experience with your regulatory environment, and whether they work with your cyber insurer.
DFIR and Legal Considerations
DFIR activities have significant legal implications. Evidence collected incorrectly may be inadmissible in legal proceedings. Regulatory notification obligations (GDPR 72-hour notification, SEC four-day material incident disclosure) create time pressure that must be balanced against investigation completeness. Attorney-client privilege can be extended to DFIR investigations when conducted at the direction of legal counsel — a significant protection against disclosure in litigation.
For comprehensive DFIR guidance including investigation methodology, tooling, and regulatory considerations, download the free book Incident Response for Business Continuity, co-authored with Binalyze.
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