Preparation: Building an Incident Response Plan and Team

Why Preparation Is the Foundation of Incident Response

Of the four phases in the NIST SP 800-61 Rev. 2 incident response lifecycle—Preparation; Detection and Analysis; Containment, Eradication, and Recovery; and Post-Incident Activity—Preparation is the most important. An organization that skips or skimps on preparation will scramble during an actual incident, wasting time and making costly mistakes. The Incident Response Plan (IRP) is the document that turns preparation into action.

What Is an Incident Response Plan?

An Incident Response Plan is a formal, written document that tells an organization exactly what to do before, during, and immediately after a security incident. According to NIST SP 800-61 Rev. 2, a strong IRP covers at minimum:

• Mission and scope – What systems and data does the plan protect? A plan that does not define scope leaves gaps that attackers can exploit.
• Roles and responsibilities – Who does what? Ambiguity during an incident leads to duplicated effort or, worse, tasks no one performs.
• Severity classification – Not every event is a major incident. Tiers (often labeled P1 through P4, or Critical/High/Medium/Low) help teams prioritize response effort and resources.
• Communication procedures – Who is notified, when, and through which channel? This includes internal stakeholders and external parties such as law enforcement, regulators, and public relations.
• Escalation paths – When does a tier-3 analyst wake up the CISO? A documented escalation tree prevents both under-reporting and executive alert fatigue.
• Asset inventory requirements – You cannot protect what you do not know you have. A current asset inventory is a prerequisite for accurate impact assessment.

Building the Incident Response Team

The Incident Response Team (IRT) is the group of people who execute the plan. NIST SP 800-61 Rev. 2 recommends that the IRT include members from IT, security operations, legal, human resources, public affairs, and senior management. In smaller organizations, one person may wear several hats, but every function must be covered.

A practical tool for defining team responsibilities is the RACI matrix:

| Role | Meaning |

|---|---|

| R – Responsible | Does the work |

| A – Accountable | Owns the outcome; signs off |

| C – Consulted | Provides input before or during the task |

| I – Informed | Receives updates; no decision authority |

For example, when isolating a compromised endpoint, the security analyst is Responsible, the security manager is Accountable, the network engineer is Consulted, and the CIO is Informed. Every task in your IRP should map to at least one R and exactly one A.

Severity Classification Tiers

A simple three- or four-tier system lets teams respond proportionally. A common structure:

• Critical (P1): Data breach in progress, ransomware spreading, critical infrastructure down. Immediate all-hands response; executive notification within minutes.
• High (P2): Confirmed malware on multiple endpoints, insider threat activity detected. Response within one to two hours; management notified.
• Medium (P3): Policy violation, single compromised account with no lateral movement. Response within one business day; team lead notified.
• Low (P4): Suspicious but unconfirmed activity, failed login spikes. Logged and reviewed during normal operations.

Severity tiers must be tied directly to the escalation tree so the on-call engineer knows exactly who to call at each level.

Communication Matrix: Internal and External Contacts

A communication matrix is a table that lists every stakeholder, the conditions under which they are contacted, the preferred channel (phone, encrypted email, secure messaging), and the expected response time. Internal contacts typically include the help desk, IT operations, security operations, legal counsel, HR, and executive leadership. External contacts may include:

• Law enforcement (FBI Cyber Division, local authorities) for criminal activity
• Regulatory bodies depending on the industry (e.g., for health data or financial data breaches)
• Internet service providers or hosting vendors for traffic blocking or takedown requests
• Cyber insurance carrier per policy requirements
• Public relations or communications team for any breach requiring customer notification

Document the contact name, title, phone number, email, and backup contact for each entry. This list must be kept current; an out-of-date contact list is nearly as bad as no list at all.

Asset Inventory: Knowing What You Are Protecting

An IRP without a current asset inventory is incomplete. You need to know which systems are in scope, what data they hold, who owns them, and how critical they are to business operations. Asset inventory should be tied to your severity classification: a server that processes payment card data is almost certainly a P1 asset, while a departmental printer may be P3 or P4. Maintain the inventory in a configuration management database (CMDB) or equivalent system and review it on a regular schedule.

Safety and Professionalism Considerations

Incident response involves handling sensitive data and, in some cases, evidence that may be used in legal proceedings. Treat all evidence with care: document your actions, preserve logs in their original form, and follow your organization's chain-of-custody procedures. Never access systems you are not authorized to access, even during an incident. Unauthorized access—even with good intentions—can constitute a legal violation under laws such as the Computer Fraud and Abuse Act. When in doubt, escalate rather than act unilaterally.