Skip to content

Chapter 4: Investigation and Response Techniques⚓︎

Initial Investigation: Verifying the Threat⚓︎

The first step in incident response is to verify that an actual threat exists. False alarms are common, so the goal of the initial investigation is to confirm whether the suspicious activity is a legitimate threat or a benign event.

Key Steps in the Initial Investigation:⚓︎

  1. Examine Alerts: Review the alerts or indicators that triggered the investigation. Was the alert triggered by a signature-based system (e.g., SIEM), behavioral anomaly detection, or a hypothesis-based hunt?
  2. Contextual Analysis: Gather additional context around the suspicious activity. For instance, who was the user involved? What systems were affected? When did the activity occur, and what external factors (e.g., new vulnerabilities, phishing campaigns) might explain the behavior?
  3. Verify Indicators: Check the validity of Indicators of Compromise (IOCs) such as IP addresses, file hashes, URLs, and domain names associated with the suspicious activity. Cross-reference these IOCs with threat intelligence sources.
  4. Confirm the Scope: Establish how far the threat has spread within the network. Does it involve just a single system, or has it spread to multiple systems or users?

Once the investigation confirms that a genuine threat is present, the team can move forward with containment and remediation.

Forensic Analysis: Techniques for Deeper Analysis⚓︎

If the initial investigation confirms a threat, forensic analysis is required to understand the full scope of the attack, how it occurred, and what systems or data may have been compromised. This stage is critical for determining how the attack began, what vulnerabilities were exploited, and what evidence is available for later analysis.

Key Forensic Techniques:⚓︎

  1. Disk Forensics: Analyzing disk images from compromised systems to look for signs of malware, backdoors, or other artifacts left by attackers.
  2. Tools: FTK Imager, Autopsy, EnCase
  3. Memory Forensics: Analyzing system memory (RAM) to detect running malware or malicious processes that may not be visible on the disk.
  4. Tools: Volatility, Rekall
  5. Network Forensics: Examining network traffic to trace the movement of the attack, understand command-and-control channels, and detect exfiltrated data.
  6. Tools: Wireshark, Zeek, NetFlow
  7. Log Analysis: Reviewing logs from SIEM systems, EDR solutions, and other monitoring tools to track the attacker’s movements and actions.
  8. Look for signs of lateral movement, privilege escalation, and exfiltration.
  9. File Integrity Checks: Verify the integrity of critical files and system configurations to see if they’ve been altered or tampered with.

By piecing together the evidence from multiple sources, forensic analysis helps build a timeline of events and a clearer picture of the attack’s scope.

Incident Response Process: Contain, Eradicate, Recover⚓︎

Once the threat is verified, the incident response (IR) process kicks into gear. The goal is to minimize damage, contain the threat, eradicate it, and restore normal operations.

1. Containment⚓︎

  • Isolate Affected Systems: Quickly isolate compromised systems from the network to prevent further lateral movement and data exfiltration.
  • Network Segmentation: Use firewalls or network segmentation to limit the spread of the attack.
  • Block Malicious Traffic: Block known malicious IPs, domains, or URLs identified during the investigation.

2. Eradication⚓︎

  • Remove Malware: Use EDR tools and manual methods to remove any malware or backdoors from compromised systems.
  • Patch Vulnerabilities: Ensure that any vulnerabilities exploited by the attacker are patched or mitigated.
  • Revoke Access: Disable compromised accounts or change credentials, especially if attackers used stolen credentials for lateral movement.

3. Recovery⚓︎

  • Restore Systems: Bring affected systems back online using clean backups or reimaging compromised systems.
  • Monitor Systems: Ensure close monitoring of restored systems for any signs of reinfection or persistent threats.
  • Verify Normal Operations: Ensure that business operations resume with minimal disruption.

The recovery phase requires careful coordination to avoid overlooking lingering threats. It's essential to have robust monitoring and detection systems in place to spot any signs of recurring activity.

Communication During an Incident⚓︎

Effective communication is critical during a cybersecurity incident. The right information needs to be shared with the appropriate teams in a timely manner.

Key Communication Principles:⚓︎

  1. Internal Communication:
  2. Incident responders should work closely with threat hunters, system administrators, and the CISO to ensure a unified response.

  3. Keep stakeholders updated regularly on the status of the incident and recovery progress.

  4. External Communication:

  5. If the incident involves third-party vendors, partners, or customers, ensure that communications are clear, transparent, and compliant with legal or regulatory requirements.

  6. In the case of a data breach, be prepared for notifications under laws like GDPR or HIPAA.

  7. Executive Communication:

  8. Provide executives and leadership with regular, digestible updates, focused on high-level impacts, response actions, and recovery timelines.
  9. Avoid jargon, and focus on actionable information that allows leaders to make informed decisions.

Clear communication can help prevent confusion, reduce panic, and ensure a coordinated and effective response.

Post-Incident Activities: Lessons Learned and Improvement⚓︎

Once the threat has been eradicated and normal operations are restored, the post-incident review begins. This phase is crucial for identifying lessons learned and improving future response efforts.

Post-Incident Activities:⚓︎

  1. Root Cause Analysis: Determine how the threat entered the environment in the first place. Was it a vulnerability, phishing attack, or insider threat? Identifying the root cause helps in mitigating similar incidents in the future.
  2. Incident Report: Document all findings and actions taken during the incident. This report should include:
  3. A timeline of the attack
  4. Indicators of compromise (IOCs)
  5. Remediation steps taken
  6. Any new lessons learned
  7. Update Detection and Prevention Controls:
  8. Revise or implement new security policies, controls, or monitoring systems to detect similar attacks in the future.
  9. Update signature databases, SIEM rules, and threat intelligence feeds to reflect new IOCs or TTPs identified during the incident.
  10. Training and Awareness:
  11. Share incident findings with the broader team to improve security awareness and provide training on identifying and responding to similar threats.
  12. Consider conducting tabletop exercises to practice future incident responses.

The post-incident phase is an opportunity to refine the organization’s security posture and ensure that lessons learned translate into more effective prevention and detection capabilities.

Collaboration with Other Teams⚓︎

While threat hunters play a central role in detecting and mitigating threats, they must work closely with other teams during an incident:

  • Incident Response Team (IRT): Incident responders are responsible for executing containment, eradication, and recovery efforts. Threat hunters help identify the scope of the attack and confirm its nature.
  • SOC (Security Operations Center): The SOC monitors security alerts and assists in detecting threats. During an incident, they provide real-time data and context.
  • Legal and Compliance Teams: Work with legal teams to understand regulatory obligations, especially in the case of a breach. Compliance teams help ensure that reporting and notifications meet legal requirements.
  • Public Relations: If a significant breach occurs, PR teams may need to communicate with the public, customers, or stakeholders. Their messaging should be aligned with internal findings.

Collaboration ensures that every team is aligned and works toward a common goal of mitigating the threat and minimizing the impact.

Case Studies and Real-World Examples⚓︎

Case Study 1: The WannaCry Ransomware Attack⚓︎

In 2017, the WannaCry ransomware attack affected thousands of organizations worldwide. The investigation revealed that the attackers exploited a vulnerability in Windows SMB (Server Message Block) protocol. The attack spread quickly across vulnerable systems.

  • Investigation: The incident response team used forensic analysis tools to identify the systems affected by the ransomware and determine the method of propagation.
  • Response: Systems were isolated, and patches were applied to close the SMB vulnerability. The incident was contained within hours, but it highlighted the importance of patching and maintaining up-to-date security practices.
  • Lessons Learned: Automated patching processes were put in place, and incident response playbooks were updated to better handle future ransomware attacks.

Conclusion⚓︎

In this chapter, we’ve covered the key techniques for investigating and responding to cybersecurity threats. From the initial investigation to forensic analysis, containment, eradication, and recovery, an effective response can minimize damage and restore normal operations. Post-incident activities ensure that organizations learn from their mistakes and improve their defenses for the future.