Major Security Incident Management

1. Purpose & Scope

• Purpose:

  Provide a command-and-coordination playbook for Sev 0 or major security incidents. Use this playbook to establish incident command, run the war room, coordinate multiple technical playbooks, manage executive/legal communications, prioritise recovery, and track decisions until the incident is downgraded or closed.

• Scope:

  Applies to security incidents with major business, customer, regulatory, operational, or executive impact. This playbook does not replace technical playbooks; it coordinates them when the incident exceeds a single-team or single-scenario response.

2. Incident Identification & Criteria

Incident Type: Major Security Incident Management

Trigger Conditions:

Initiate this playbook when any of the following occur:

• Incident is declared Sev 0 or equivalent major incident
• Multiple technical playbooks must run concurrently under one command structure
• Critical business services, customer-facing systems, identity infrastructure, cloud tenant, backups, or security tooling are materially impacted
• Executive, legal, regulatory, customer, public, vendor, or law enforcement coordination is required
• Response will span multiple teams, geographies, shifts, or recovery phases

Severity Levels:

3. Roles & Responsibilities

• Incident Commander: Owns command, severity, priorities, operating cadence, decision log, escalation, and downgrade/closure decisions.
• Deputy Incident Commander: Maintains action tracker, follows up on blockers, and supports continuity during extended response.
• Technical Lead: Coordinates technical workstreams and ensures relevant playbooks/runbooks are executed.
• Communications Lead: Coordinates stakeholder updates, executive briefings, internal messaging, and approved external communications.
• Scribe: Maintains incident timeline, action tracker, decision log, and evidence references.
• Other Roles:
  • Legal / Compliance: Assesses regulatory, contractual, legal, insurance, and disclosure obligations.
  • Business / Service Owners: Confirm business impact, recovery priority, customer impact, and operational constraints.
  • Vendor Owner / Procurement: Coordinates third-party support where vendor action is required.
  • Customer Support / Success: Coordinates customer-impact handling and support readiness.
  • Recovery Lead: Coordinates service restoration priorities, dependencies, and validation.

4. Initial Actions

• Immediate Steps:

  • Confirm the major incident declaration, severity, Incident Commander, Technical Lead, Communications Lead, Scribe, and executive sponsor.
  • Open the major incident war room, action tracker, decision log, and operating cadence.
    • 📘 SOP-007: Major Incident War Room Management
  • Page required engineering, security, platform, application, identity, cloud, network, legal, communications, support, and vendor-owner teams.
    • 📘 SOP-001: Paging an Engineering Team's On-Call
  • Identify active technical playbooks and assign owners for each workstream.
  • Start executive/legal communication process if major impact, customer impact, regulated data, or external communication is possible.
    • 📘 SOP-003: Escalation, Legal & Executive Communications

  Decision Point:

  • If the incident does not require major incident coordination → continue under the relevant technical playbook only.
  • If major coordination is required → continue this playbook alongside all relevant technical playbooks.
  • If external communications may be required → engage Legal/Compliance and Communications Lead before any external statement.

5. Investigation & Analysis

• Evidence Collection:

  • Confirm each technical workstream is preserving evidence through its linked playbook and runbooks.
  • Track evidence locations, owners, collection status, and gaps in the major incident action tracker.
  • Preserve command decisions, timelines, status updates, customer-impact assessments, and legal guidance as part of the incident record.

• Analysis Steps:

  • Maintain a consolidated incident timeline covering detection, impact, containment, eradication, recovery, communications, and decisions.
  • Track active technical workstreams and linked playbooks.
  • Confirm each workstream has a current hypothesis, scope, owner, next action, blocker, and next update time.
  • Maintain a business impact assessment covering services, customers, data, regions, revenue, operations, and recovery dependencies.

  Decision Point: Run the relevant technical playbooks concurrently based on the incident drivers:

  • Ransomware or destructive activity → PB-002: Ransomware
  • Malware or suspicious execution → PB-003: Endpoint Malware Infection / PB-011: Suspicious Execution
  • Account, token, credential, or cloud identity compromise → PB-004: Account Takeover
  • Data exposure, staging, or exfiltration → PB-005: Data Exfiltration
  • Cloud environment compromise → PB-007: Cloud Compromise
  • Web application compromise → PB-008: Web Application Attack
  • Privilege escalation → PB-009: Privilege Escalation
  • Lateral movement → PB-010: Lateral Movement
  • Third-party compromise → PB-012: Third-Party Compromise
  • DDoS or availability attack → PB-013: Distributed Denial of Service
  • Lost/stolen device with major impact → PB-014: Lost & Stolen Device
  • Active exploitation → PB-015: Active Exploitation
  • Vulnerability or zero-day emergency → PB-017: Vulnerability Response / PB-018: Zero-Day Response

6. Containment, Eradication & Recovery

• Containment Actions:

  • Confirm each technical workstream has an owner, containment objective, current action, risk, and rollback plan.
  • Prioritise containment actions that reduce active attacker access, customer impact, data exposure, destructive risk, and business-critical service impact.
  • Record containment decisions, risk acceptances, and business tradeoffs in the decision log.

• Eradication Steps:

  • Confirm each technical playbook owns eradication of incident-specific root cause, persistence, malicious access, and vulnerable exposure.
  • Track cross-workstream dependencies such as identity resets, network segmentation, rebuilds, vendor support, legal holds, and business approvals.
  • Ensure eradication is not declared complete until technical leads confirm root cause and persistence have been addressed.

• Recovery Steps:

  • Establish recovery priority based on business criticality, dependency order, customer impact, safety, and residual risk.
    • 📘 RB-RECOVERY-001: Recovery & Restoration Coordination
  • Gate service restoration on containment status, integrity validation, monitoring readiness, and business owner approval.
  • Downgrade the major incident only after the Incident Commander confirms stable containment, recovery path, communications status, and remaining risk.

7. Communication & Escalation

• Internal Communication:

  • Run major incident cadence, action tracking, decision logging, and status updates through the war room SOP.
    • 📘 SOP-007: Major Incident War Room Management
  • Use geo handoff when command or workstreams transition across shifts or regions.
    • 📘 SOP-002: Incident Handoff Between Geos
  • Notify affected users or broader employee groups when user action is required.
    • 📘 SOP-004: User Notification During a Security Incident

• External Communication:

  • Coordinate executive, legal, regulatory, customer, partner, insurer, media, or law enforcement communications through approved processes.
    • 📘 SOP-003: Escalation, Legal & Executive Communications
  • Coordinate vendor communications through the vendor communication SOP.
    • 📘 SOP-005: Vendor Communication During a Security Incident

• Escalation Criteria:

  Condition	Escalate To
  Major incident cadence, action tracking, or decision logging required	SOP-007: Major Incident War Room Management
  Executive, legal, regulatory, customer, media, or insurer coordination required	SOP-003: Escalation, Legal & Executive Communications
  Vendor or provider support required	SOP-005: Vendor Communication During a Security Incident
  Multi-geo or long-running response requires command transfer	SOP-002: Incident Handoff Between Geos
  Affected-user action or advisory required	SOP-004: User Notification During a Security Incident

8. Post-Incident Activities

• Lessons Learned:

  • Conduct a PIR covering command structure, severity decisions, communication cadence, decision quality, handoffs, technical workstream coordination, recovery prioritisation, and stakeholder outcomes.
  • Review whether the major incident was declared early enough and whether it was downgraded at the right time.
  • Identify coordination gaps, unclear ownership, delayed decisions, missing evidence, or communication failures.

• Documentation Updates:

  • Update technical playbooks, SOPs, escalation paths, contact lists, status templates, decision log templates, and recovery priority guidance based on PIR findings.
  • Track all follow-up actions with owners, due dates, and validation criteria.

9. References & Linked Resources

• Playbooks:

  • PB-002: Ransomware
  • PB-003: Endpoint Malware Infection
  • PB-004: Account Takeover
  • PB-005: Data Exfiltration
  • PB-007: Cloud Compromise
  • PB-008: Web Application Attack
  • PB-009: Privilege Escalation
  • PB-010: Lateral Movement
  • PB-011: Suspicious Execution
  • PB-012: Third-Party Compromise
  • PB-013: Distributed Denial of Service
  • PB-014: Lost & Stolen Device
  • PB-015: Active Exploitation
  • PB-017: Vulnerability Response
  • PB-018: Zero-Day Response

• Runbooks:

  • RB-RECOVERY-001: Recovery & Restoration Coordination

• SOPs:

  • SOP-001: Paging an Engineering Team's On-Call
  • SOP-002: Incident Handoff Between Geos
  • SOP-003: Escalation, Legal & Executive Communications
  • SOP-004: User Notification During a Security Incident
  • SOP-005: Vendor Communication During a Security Incident
  • SOP-007: Major Incident War Room Management

10. Appendices

• Expected Outputs:

  • Major incident declaration and severity record
  • Active workstream list and owners
  • War room link, action tracker, and decision log
  • Consolidated incident timeline
  • Executive/legal/customer/vendor communication records
  • Recovery priority and dependency plan
  • Downgrade or closure decision record
  • PIR action items and owners

• Common Failure Modes:

  • Declaring a major incident too late
  • Running multiple technical playbooks without a single command structure
  • Missing decision logs or action owners
  • Allowing recovery work to start before containment and integrity validation
  • Sending external communications before legal and communications approval
  • Losing context during long-running or multi-geo handoffs

Contributor

Vishal Thakur GitHub: https://github.com/malienist

Contributed to the Arcana Incident Response Documentation Framework.