Incident Response Playbook for Data Breach and Information Leakage (Updated 2025)

This Data Breach and Information Leakage Incident Response Playbook provides a detailed, structured approach to identifying, containing, remediating, and recovering from data breaches and unauthorised disclosures of sensitive information. This version integrates modern practices such as the use of Data Loss Prevention (DLP) tools, public monitoring techniques, and coordination with legal and regulatory bodies.

1. Preparation

Objective: Establish protocols, contacts, and security measures to minimise the risk of data breaches and ensure an efficient response.

Key Steps:

1. Identify Internal Contacts:

   • Security team, SOC analysts, CISO, legal advisors, public relations (PR), human resources (HR), and regulatory compliance contacts (e.g., DPO).

2. Establish External Contacts:

   • Law enforcement, Computer Emergency Response Teams (CERTs), data protection regulators, and third-party investigators.

3. Develop Communication Plans:

   • Prepare internal and external communication strategies to manage breach notifications, including regulatory disclosure requirements (e.g., GDPR).

4. Define Security Policies:

   • Identify and classify valuable assets.

   • Ensure security policies are up-to-date, with escalation procedures clearly documented.

   • Conduct regular awareness and training sessions on data protection.

5. Implement Security Tools:

   • Deploy and configure DLP tools to monitor and prevent unauthorised data transfers.

   • Enable monitoring and logging of system access, emails, browser activity, file transfers, and network usage.

2. Identification

Objective: Detect and confirm a data breach, determine its scope, and notify relevant stakeholders.

Detection Sources:

1. Internal Reports:

   • Employee reports of suspicious activity.

   • Alerts from DLP tools, SIEM systems, or anomaly detection tools.

2. Public Monitoring:

   • Monitor search engines, social media, forums, and ransomware extortion websites for signs of leaked data.

3. Email and Network Analysis:

   • Analyse email logs for suspicious data transfers.

   • Investigate proxy, VPN, and SSH logs for external data transmissions.

   • Review SIEM alerts for anomalies in system or user behaviour.

4. Device Inspection:

   • Check endpoints for evidence of data transmission via USB devices, external hard drives, or local files.

   • Perform a forensic analysis of desktop and laptop computers if necessary.

5. Confirmation:

   • Verify the incident through forensic analysis and evidence collection.

   • Ensure regulatory and legal teams are informed of any confirmed breach that may require external reporting.

3. Containment

Objective: Minimise the impact of the breach by isolating affected systems and preventing further data exposure.

Steps:

1. Notify Key Stakeholders:

   • Inform management, PR, HR, and legal teams.

   • Engage regulatory compliance teams if notification is legally required.

2. Block Data Transfers:

   • Use DLP tools, firewalls, and proxy servers to block the data leak source (e.g., URL, IP, or malicious process).

   • Suspend compromised user accounts and access credentials.

3. Isolate Systems:

   • Disconnect compromised systems from the network to prevent further data transmission.

   • Secure evidence by taking forensic snapshots of affected systems.

4. Preserve Logs and Evidence:

   • Capture logs related to network traffic, file transfers, system access, and endpoint activity.

   • Ensure evidence integrity to support potential investigations and regulatory compliance.

4. Remediation

Objective: Remove the threat, mitigate further risks, and implement additional security measures.

Steps:

1. Remove Exposed Data:

   • Request removal of disclosed data from public servers, websites, or social media platforms.

   • Use takedown notices for non-compliant platforms (coordinate with legal and regulatory bodies).

2. Monitor for Data Spread:

   • Track data propagation across social networks, forums, and other online platforms.

   • Use threat intelligence services to monitor the dark web for further signs of data misuse.

3. Strengthen Security Controls:

   • Apply patches and updates to address vulnerabilities exploited during the breach.

   • Review and tighten access control policies.

4. Legal Actions:

   • Provide detailed evidence to HR and legal teams for internal disciplinary actions or formal complaints.

   • Notify regulatory authorities if required by law (e.g., GDPR breach notification).

5. Recovery

Objective: Restore affected systems, resume business operations, and reassure stakeholders of the organisation's improved security posture.

Steps:

1. System Restoration:

   • Rebuild or reconfigure compromised systems to eliminate any lingering threats.

   • Conduct integrity checks to ensure that critical files and services are secure.

2. Communicate with Employees and Clients:

   • Notify employees of the breach and provide updated guidelines on data handling.

   • Inform affected clients, customers, or business partners as required by contractual or regulatory obligations.

3. Enhanced Monitoring:

   • Implement continuous monitoring of critical assets and high-risk activities.

   • Validate that no unauthorised data access or transfer occurs after remediation.

6. Lessons Learned

Objective: Document the incident details, assess response performance, and improve future incident handling capabilities.

Steps:

1. Incident Report:

   • Include details such as:

     • Root cause analysis.

     • Timeline of key events.

     • Actions taken during containment, remediation, and recovery.

     • Indicators of compromise (IOCs).

2. Post-Incident Review:

   • Conduct a review with all relevant teams to evaluate the effectiveness of the response.

   • Identify areas for improvement in detection, communication, and response protocols.

3. Policy and Playbook Updates:

   • Update the incident response playbook and security policies based on lessons learned.

   • Enhance training programs to address newly identified risks.

4. Continuous Improvement:

   • Perform regular security audits and tabletop exercises to test response readiness.

   • Strengthen partnerships with external security service providers, law enforcement, and regulatory bodies.

Conclusion

This Data Breach and Information Leakage Playbook equips organisations with a comprehensive response strategy to mitigate the risks of unauthorised data disclosures. Continuous updates to detection capabilities, employee training, and regulatory compliance measures are essential to maintaining a strong security posture.

For additional resources, including forensic tools, threat monitoring templates, and communication guidelines, contact your cybersecurity operations team.