SIRS key terms

A repeatable sequence of phases that structures how an organization prepares for, detects, contains, eradicates, and recovers from a security incident, then learns from it. It gives teams a common vocabulary and clear decision points.

The phase in which an organization builds the people, processes, and technology needed before an incident occurs, including plans, playbooks, tooling, training, and communication paths. Weak preparation usually surfaces as slow, improvised response.

The phase focused on identifying potential security events, validating whether they are genuine incidents, determining scope and impact, and documenting findings well enough to drive later decisions. It converts raw alerts into an actionable understanding of what happened.

The phase that limits the spread of an incident, removes the attacker's foothold and malicious artifacts, and restores affected systems to normal operation under monitoring. These activities often overlap and are revisited as new evidence appears.

The phase after recovery in which the team reviews what happened, measures response effectiveness, and produces improvement actions. Its output feeds back into preparation, closing the loop of the response life cycle.

A documented, approved set of policies, roles, responsibilities, and procedures that guides the organization's response to security incidents. It defines authority, escalation paths, and priorities rather than step-by-step technical actions.

A focused, step-by-step procedure for handling a specific incident type, such as ransomware or business email compromise. Playbooks translate the broader response plan into concrete actions, decision points, and expected outputs.

A low-level operational guide describing exactly how to perform a technical task, such as isolating a host or resetting credentials. Runbooks are typically referenced from playbooks and are written for the person executing the action.

The group of people with defined roles who carry out detection, analysis, containment, and recovery activities. Membership often spans security operations, IT, legal, communications, and business units, with a designated incident commander.

The individual who directs response activities, makes or approves key decisions, and coordinates communication among responders and stakeholders. The role centralizes authority so that actions remain consistent during high-pressure events.

A discussion-based simulation in which participants walk through a realistic incident scenario to test plans, roles, and decision-making without touching production systems. It reveals gaps in communication and procedures before a real event.

The process of rapidly assessing and prioritizing incoming alerts or reported events by severity, confidence, and potential business impact. Triage determines which events receive immediate investigation and which can be queued or closed.

Observable evidence suggesting that a system or network has been breached, such as malicious file hashes, unusual outbound connections, or known attacker infrastructure. Indicators support detection but can become stale as adversaries change tools.

Observable behavior or technique that signals an adversary is actively conducting an intrusion, focusing on intent and method rather than static artifacts. Because it describes behavior, it tends to remain useful longer than file-based indicators.

An alert that appears to indicate malicious activity but, after investigation, is determined to be benign or expected behavior. Tracking false positive rates helps teams tune detection rules without losing genuine coverage.

A real malicious event that a detection capability fails to identify or report. False negatives are harder to measure than false positives and often surface only through later discovery, external notification, or retrospective analysis.

A classification that reflects the actual or potential business impact of an incident, used to drive escalation, resourcing, and reporting obligations. Severity is usually reassessed as scope and impact become clearer.

The formal decision that an event meets the organization's criteria for an incident, triggering the response plan, roles, and notification paths. Clear declaration criteria prevent both overreaction and delayed response.

The process of raising an incident to higher authority, additional teams, or management when severity, scope, or uncertainty exceeds defined thresholds. Escalation paths and timeframes should be documented in advance.

The chosen approach for stopping an incident from spreading, ranging from short-term isolation of affected systems to longer-term segmentation or credential revocation. The strategy balances limiting damage against preserving evidence and business continuity.

Disconnecting or restricting a system or account so it cannot communicate with other resources or be used by an attacker. Isolation is a common immediate containment action but can destroy volatile evidence if performed carelessly.

The removal of the root cause of an incident, including malware, attacker accounts, persistence mechanisms, and exploited vulnerabilities. Eradication is complete only when the entry path and footholds are addressed.

The process of restoring affected systems, data, and services to normal operation while confirming that the threat has been removed. Recovery includes validation testing, heightened monitoring, and a defined return-to-production decision.

The practice of capturing and protecting data in a way that maintains its integrity and usability for investigation or legal proceedings. It includes documenting chain of custody and using forensically sound collection methods.

A documented record of who collected, handled, transferred, and stored evidence, and when each action occurred. A complete chain supports the credibility of evidence if it is used in legal or disciplinary proceedings.

A bit-for-bit copy of a storage device or memory space, created with tools that verify integrity through hashing. Investigators analyze the copy rather than the original to avoid altering evidence.

A structured review after an incident that identifies what worked, what failed, and which improvements should be implemented. Effective reviews assign owners and deadlines so findings become changes rather than observations.

A written record summarizing an incident's timeline, impact, response actions, and identified improvement items. It serves as the durable artifact of the post-incident review and supports trend analysis across incidents.

A structured method for determining the underlying conditions that allowed an incident to occur, beyond the immediate technical trigger. Its findings inform eradication and long-term preventive controls.

A chronological record of events, actions, and decisions during an incident, including timestamps and sources. A reliable timeline supports analysis, reporting, legal defensibility, and post-incident review.

The act of informing required parties, such as regulators, affected individuals, law enforcement, or partners, that an incident occurred. Notification obligations often have fixed deadlines tied to specific data types and jurisdictions.

A legal or contractual obligation to inform affected individuals and authorities when personal or protected data is compromised. Trigger conditions, content requirements, and deadlines vary by jurisdiction and sector.

Submitting incident information to a supervisory or sector authority as required by law or regulation within prescribed timeframes. Sector rules may impose stricter timelines and content requirements than general privacy laws.

A judgment about whether an incident's impact is significant enough to affect decisions, disclosures, or obligations. In securities contexts, materiality can determine whether and when an incident must be publicly disclosed.

Information relating to an identified or identifiable individual, whose handling is governed by privacy and data protection laws. Incident response must account for personal data exposure when assessing impact and notification duties.

A scheduled or event-driven communication that tells stakeholders what is known, what is being done, and what is needed next. Consistent updates reduce rumor, duplication of effort, and pressure on responders.

The planned sharing of incident information with internal and external audiences, tailored to their needs and legal constraints. It includes message ownership, approval paths, channels, and cadence.

Information about adversaries, their tools, and their behaviors, collected and analyzed to inform detection and response decisions. It helps teams prioritize alerts and anticipate likely next steps during an incident.