A Practical Guide to Your Computer Incident Response Plan (CSIRP)

A robust computer incident response plan (CSIRP) is a foundational element of organisational resilience, serving as the critical framework that distinguishes a managed security event from a business-disrupting crisis. This plan provides the definitive playbook for navigating the complexities of a security breach, establishing a clear, repeatable process for detection, containment, and recovery while minimising operational impact.

The Strategic Imperative of Incident Response for Australian Businesses

The perception of cyber attacks as a distant threat is a strategic vulnerability that Australian businesses can no longer afford. For organisations of all sizes, from agile SMEs to established enterprises, a reactive security posture is a direct pathway to significant financial and reputational damage. As the threat landscape evolves in frequency and sophistication, proactive cyber defence must be treated as a core business function, not merely an IT-level concern.

A well-architected computer incident response plan transforms a potential disaster into a structured, manageable process. It mitigates the organisational paralysis that often accompanies a security crisis by providing clear, decisive steps for response teams to follow when every second is critical.

Safeguarding Business Continuity and Stakeholder Trust

At its core, an incident response plan is a strategic asset for ensuring business continuity. The capability to contain a threat rapidly directly reduces operational downtime and the associated revenue loss. This proactive posture is also fundamental to maintaining stakeholder trust and protecting brand equity, particularly for organisations entrusted with sensitive data.

An incident response plan is an integral component of a broader business continuity plan and disaster recovery plan, where all elements work in concert to build organisational resilience. This structured approach communicates a powerful message of security maturity to stakeholders, partners, and clients. For further analysis, refer to our guide on the ASD’s incident response guidance.

Meeting Evolving Compliance Obligations

Beyond operational resilience, a formal plan is essential for meeting legal and regulatory obligations. In Australia, frameworks such as the Notifiable Data Breaches (NDB) scheme mandate prompt, structured action and reporting. The absence of a documented and tested response process can expose an organisation to significant regulatory penalties and legal challenges.

A documented plan provides auditable evidence of an organisation’s commitment to its security responsibilities. It is a key requirement for achieving and maintaining certifications such as ISO 27001 and SOC 2, which are increasingly prerequisites for securing enterprise-level contracts.

The Australian government has reinforced this imperative. In 2025, an overwhelming 90% of Australian Commonwealth entities now maintain a formal incident response plan, an increase from 86% in the preceding year. This trend is a direct response to the escalating threat environment; the Australian Signals Directorate (ASD) managed over 1,200 cyber security incidents in the last reporting period—an 11% year-on-year increase. Without robust plans, similar incidents could severely impact the SMEs and enterprises in critical sectors like financial services and healthcare. The complete analysis is available in the Australian Government’s ‘Commonwealth Cyber Security Posture in 2025’ report.

The Australian Cyber Security Centre provides authoritative guidance for organisations seeking to formalise their incident response strategies.

This guidance underscores the critical role of a structured, phased approach, positioning preparation as the bedrock of an effective defence posture. By establishing the strategic “why” before detailing the operational “how,” an organisation can cultivate a security culture that effectively safeguards its future.

Assembling and Defining the Incident Response Team

An incident response plan remains a theoretical document until it is supported by a clearly defined team. During a security breach, ambiguity regarding roles and responsibilities leads to indecision and paralysis. This wasted time is precisely when a minor issue escalates into a major crisis. Constructing a Computer Incident Response Team (CIRT) is not a matter of listing job titles; it is about assigning clear, actionable duties designed to function under intense pressure.

An effective CIRT is a cross-functional unit, integrating expertise from legal, communications, and executive leadership alongside technical specialists. Each member must have a precise understanding of their function to ensure the response is coordinated and decisive, rather than chaotic and reactive.

Core Roles of the Computer Incident Response Team

To achieve clarity of action when every second counts, core roles must be defined well in advance. While specific titles may vary based on organisational size, the functional responsibilities remain consistent. This structure should be viewed less as a rigid hierarchy and more as a specialised unit where each expert has a clear mission.

• Incident Commander: The strategic leader of the response effort. This individual is not necessarily the most technical expert but is a decisive leader responsible for coordinating all team activities, securing resources, and making critical decisions, such as authorising system shutdowns or public notifications.

• Technical Lead: The lead investigator responsible for directing all hands-on forensic analysis, containment, and eradication efforts. This role is tasked with identifying the attack vector, determining the scope of the breach, and guiding the technical team in remediating the threat from the environment.

• Communications Lead: This function manages the controlled flow of information, both internally and externally. The Communications Lead crafts and disseminates messaging for employees, executives, customers, and regulators, ensuring all communications are accurate, timely, and aligned with legal counsel.

Clarifying Responsibilities with a RACI Matrix

Defining roles is the foundational step, but assigning ownership for specific tasks is what makes a plan operationally effective. A RACI (Responsible, Accountable, Consulted, Informed) matrix is an indispensable tool for this purpose. It maps critical incident response tasks to CIRT roles, explicitly defining who executes the work, who holds ultimate ownership, and who must be kept informed.

Consider a ransomware attack targeting a healthcare provider. A RACI chart provides immediate clarity on the division of labour.

Core Incident Response Team Roles and Responsibilities (RACI Matrix)

This simplified matrix illustrates how responsibilities are distributed during an incident, preventing confusion and ensuring all critical actions are owned.

This structured approach prevents critical steps from being overlooked and mitigates conflicts between team members during a high-stress event. When the plan and the team are structured correctly, a clear path forward emerges. Organisations seeking assistance in defining these roles can leverage professional incident response services that provide this specialised expertise.

A well-defined team structure transforms the response from a chaotic scramble into a measured, methodical process. The objective is to enable decisions based on the plan, not on emotion.

Beyond technical roles, the response plan must incorporate clear communication protocols. An effective response hinges on keeping all internal and external stakeholders appropriately informed. To formalise this process, it is advisable to review your essential stakeholder communication plan template. This provides the Communications Lead with pre-approved messaging and contact lists, saving invaluable time when it matters most.

Mastering the Six Phases of the Incident Response Lifecycle

In the event of a cyber incident, a structured, repeatable process is the most effective defence. A chaotic, panicked response exacerbates the situation, increasing downtime and costs. By adopting the globally recognised six-phase incident response lifecycle, organisations can shift from reactive turmoil to a focused, methodical approach, ensuring every action is deliberate and impactful.

This framework, which aligns with standards such as NIST and ISO 27001, provides a clear roadmap for navigating a security breach—from initial alert to post-incident analysis. It represents the operational heart of any credible computer incident response plan.

Phases 1 & 2: Preparation and Identification

The most critical work occurs long before an incident materialises. Preparation involves equipping the response team with the necessary tools, training, and documentation to act decisively. This includes clearly defined roles, secure communication channels, and ready access to essential security technologies. Failure in this phase undermines the entire response process.

The Identification phase commences the moment an alert is triggered. The objective is to rapidly and accurately determine if a security event constitutes a genuine incident or a false positive. Not every anomalous log entry signifies a breach. The team requires clear criteria for classifying incidents based on potential business impact, allowing for appropriate escalation from minor events to major crises. This ensures that significant threats receive immediate attention while preventing the misallocation of resources on false alarms.

Phase 3: Containment

Once an incident is confirmed, the immediate priority is to limit its impact. Containment focuses on preventing the threat from propagating and causing further damage. This requires a delicate balance: isolating affected systems without disrupting critical business operations unnecessarily.

Containment strategies include:

• Short-term containment: Isolating a compromised endpoint from the network to prevent malware from spreading to other machines.

• Long-term containment: Leveraging network segmentation to quarantine the threat while a comprehensive remediation plan is developed.

A common error is to enact a complete, indiscriminate shutdown of all systems. A skilled response team employs surgical containment measures to isolate the threat while preserving crucial forensic evidence and protecting the broader environment.

Phases 4 & 5: Eradication and Recovery

With the incident contained, the next objective is to eliminate the threat from the environment permanently. Eradication involves a thorough cleansing of all affected systems to ensure no remnants of the attacker remain. This may include removing malware, patching exploited vulnerabilities, and disabling compromised user accounts.

Following eradication, Recovery focuses on safely restoring services to normal operation. This phase is more than a simple reactivation of systems; it entails restoring data from clean backups, closely monitoring systems for any signs of reinfection, and verifying that all security controls are fully functional before resuming business-as-usual operations. A rushed recovery process significantly increases the risk of reinfection.

Phase 6: Lessons Learned

This final phase is arguably the most critical for building long-term organisational resilience. The Lessons Learned stage, also known as a post-incident review, is a blameless analysis of the entire response effort. The team convenes to discuss what functioned effectively, what failed, and the underlying causes.

Key questions to address include:

• Did our detection tools perform as expected?

• Was the communication plan effective under pressure?

• Were there unforeseen gaps in our response playbooks?

• What new security controls could have prevented this incident?

The output of this phase is a clear action plan for improvement. The insights gained are fed directly back into the computer incident response plan, leading to updated security policies, refined procedures, and enhanced team training. This creates a powerful feedback loop that ensures the organisation becomes stronger and more prepared after every incident. Our ACSC-aligned incident response plan template provides a structured starting point for this process.

Aligning Your Plan with Australian Compliance Frameworks

In the Australian context, a robust computer incident response plan is no longer just a component of good security practice—it is a central element of the compliance mandate. If response activities are not aligned with key regulatory and industry standards, an organisation faces not only operational disruption but also the tangible risks of significant fines, loss of certification, and severe reputational damage.

For any organisation handling sensitive information, the ability to demonstrate an audit-ready incident management process is fundamental to building trust with customers, partners, and regulators. The objective is to develop a plan that is not only effective under the pressure of a live incident but also demonstrably meets the requirements of the frameworks that govern the business.

When executed correctly, the incident response plan transcends its operational function to become a strategic asset for governance, risk, and compliance (GRC) initiatives, streamlining audits and evidencing a commitment to security excellence.

Mapping Response Activities to ISO 27001

ISO 27001 is the global benchmark for information security management systems (ISMS), and its controls directly address incident handling. For Australian businesses pursuing this certification, a documented and tested incident response plan is non-negotiable.

Specifically, Annex A control A.16.1.7 (Information security incident management planning and preparation) mandates that organisations establish, document, and maintain clear procedures to manage security incidents. In practical terms, this requires the plan to define the roles, responsibilities, and processes for every stage of the incident lifecycle, from initial detection through to the post-incident review.

A well-structured plan serves as direct evidence for auditors, demonstrating a methodical and repeatable approach rather than an ad-hoc response. It proves the existence of a formal process to respond to, communicate about, and learn from security events—the core tenets of the standard.

The ASD Essential 8 and Incident Response

The Australian Signals Directorate’s (ASD) Essential 8 provides a prioritised list of mitigation strategies designed to defend against common cyber threats. While not a formal certification, its adoption is mandatory for government agencies and is widely regarded as best practice for all other organisations.

Several of the Essential 8 strategies are intrinsically linked to incident response. For example, robust processes for managing administrative privileges and patching applications serve as preparatory controls that reduce the likelihood of an incident.

However, when an incident does occur, the plan’s effectiveness in rapidly identifying, containing, and recovering from the threat directly supports the Essential 8’s objective of limiting incident impact. A tested plan provides demonstrable proof that these mitigation strategies can be executed effectively under pressure.

This alignment is particularly critical for organisations operating within government supply chains or critical infrastructure sectors, where adherence to ASD guidance is often a contractual obligation.

Meeting SOC 2 Trust Services Criteria

For technology companies and service providers, a SOC 2 report is often a key enabler for enterprise contracts. The framework is structured around five Trust Services Criteria, with the Security criterion (also known as the common criteria) serving as the foundation.

The Security criterion explicitly requires organisations to have procedures in place to detect, respond to, and mitigate security incidents. An auditor will seek clear evidence of a formal incident response plan that includes:

• A dedicated response team with clearly defined roles.

• Incident classification procedures for prioritising response efforts.

• Containment and eradication playbooks to manage active threats.

• A post-incident review process to drive continuous improvement.

Attempting to achieve a clean SOC 2 attestation without a documented computer incident response plan that addresses these points is practically impossible.

The table below illustrates how specific incident response activities map directly to these key frameworks, serving as a useful tool for compliance managers to ensure their plan is audit-ready.

Incident Response Plan Alignment with Key Compliance Frameworks

As demonstrated, the core activities of a robust incident response plan do not exist in isolation; they constitute the evidence auditors require to validate compliance with major Australian and international standards.

Validating Your Plan with Realistic Drills and Simulations

A computer incident response plan that remains untested is merely a theoretical document. True organisational resilience is not achieved by writing a plan but is forged through practice, pressure-testing, and continuous improvement. This is the critical phase where theory transitions to reality, transforming the plan into a living, battle-ready strategy.

Without regular testing, an organisation operates with significant blind spots. It is impossible to know if communication channels will withstand pressure, if team members fully comprehend their roles, or if technical playbooks are effective. Drills and simulations provide the only means to identify these weaknesses in a safe, controlled environment—before a real adversary does.

Selecting the Appropriate Exercise Type

Not all tests serve the same purpose. The key is to select the right type of drill based on strategic objectives and team maturity. A new team should not be subjected to a full-scale live simulation; capability should be built incrementally over time.

• Tabletop Exercises: These are guided, discussion-based sessions where the team verbally works through a simulated incident scenario. They are the ideal starting point for testing decision-making processes, communication flows, and role clarity without impacting live systems, making them perfect for involving senior leadership and non-technical stakeholders.

• Walkthroughs: A more detailed evolution of a tabletop, this exercise involves a step-by-step review of specific playbooks. The team might physically gather to walk through a ransomware response procedure, checklist by checklist, ensuring every member understands their precise tasks.

• Technical Simulations: This is where the technical team engages in hands-on activities. In a sandboxed or segmented environment, they might confront a simulated malware infection or phishing attack. These drills are designed to test the efficacy of security tools and the technical proficiency of the response team.

• Full-Scale Simulations: The most comprehensive test, this often involves a red team exercise where an external party attempts to breach the live environment. It represents the ultimate validation of people, processes, and technology, yielding invaluable, real-world insights into an organisation’s defensive posture.

Designing a Realistic Scenario

The value of any drill is contingent on its realism. A generic scenario will fail to uncover the unique vulnerabilities within an organisation. The narrative must be designed to reflect the specific threats relevant to the industry and business context.

Consider a sophisticated business email compromise (BEC) attack targeting the finance department. The simulation could commence with a carefully crafted phishing email, leading to a compromised account and culminating in a fraudulent wire transfer request. This scenario tests everything from employee awareness to the team’s ability to rapidly detect and contain a compromised account.

A well-designed simulation should create a controlled level of stress. Its purpose is to exert just enough pressure to reveal the cracks in the computer incident response plan, enabling remediation before they can be exploited in a real crisis.

The necessity for robust testing is underscored by Australia’s current cyber landscape. According to the OAIC, there were 532 notifiable data breaches in the first half of 2025 alone. Malicious cyber attacks were the cause of 59% of these breaches, with each incident impacting an average of over 10,000 individuals. For sectors we serve, such as education and finance pursuing ISO 27001 or SOC 2, these statistics are a stark reminder of the stakes. Further details are available in the full OAIC notifiable data breach report.

Measuring Success and Driving Improvement

The objective of any test is not to pass or fail; it is to learn. Following every drill, a thorough post-mortem analysis must be conducted to capture what functioned effectively, what did not, and the root causes.

Focus on key metrics to guide this analysis:

• Time to Detect: How long did it take the team to identify the initial indicators of the simulated incident?

• Time to Respond: Once detected, how quickly did the team assemble and begin executing the plan?

• Communication Effectiveness: Were messages clear, timely, and delivered to the correct stakeholders? Were out-of-band channels utilised effectively?

• Playbook Gaps: Were there steps in a playbook that were unclear, incorrect, or missing entirely?

These findings must be used to drive direct improvements to the computer incident response plan. Every lesson learned is an opportunity to refine processes, update documentation, and schedule targeted training—ensuring the organisation becomes progressively stronger and more prepared with each exercise.

Frequently Asked Questions About Your Incident Response Plan

Even with a detailed framework, translating theory into practice raises numerous questions. As organisations develop and maintain their incident response plan, obtaining clear answers is essential for refining the approach, closing critical gaps, and building genuine team confidence.

Below, we address some of the most common questions from Australian businesses navigating the realities of incident response.

How Often Should We Test Our Incident Response Plan?

As a general guideline, an incident response plan should be tested at least annually. However, the optimal frequency is dictated by the organisation’s risk profile. A single annual test is insufficient for organisations in high-threat sectors like finance or healthcare, or for those undergoing significant IT transformation, such as a cloud migration.

For these higher-risk scenarios, a more regular testing cadence is recommended:

• Full-scale simulations: Conducted annually to validate the entire process, from detection through to recovery.

• Tabletop exercises: Held bi-annually or quarterly to maintain alignment among leadership and key stakeholders regarding their roles.

• Playbook walkthroughs: Performed quarterly for specific, high-likelihood threats like ransomware to keep the technical team’s skills and procedures current.

The objective is not to meet a compliance requirement once a year but to integrate testing as a continuous component of the security culture.

What Is the Difference Between a Disaster Recovery Plan and an Incident Response Plan?

This is a critical distinction. While the two plans are closely related, they serve fundamentally different functions. An incident response plan can be considered a specialised tool within the broader toolkit of business continuity.

An Incident Response Plan (IRP) is narrowly focused on addressing a security breach. Its purpose is to detect an adversary, eradicate their presence, and safely restore systems. It is the cybersecurity playbook for combating an active attack.

A Disaster Recovery (DR) Plan is much broader in scope. It is concerned with restoring all IT operations following any major disruption, which could be a cyber attack, a natural disaster, a critical hardware failure, or a wide-scale power outage. When a security incident is severe enough to cause a disaster-level outage, the IRP functions as the initial phase of the broader DR plan.

What Are the Most Common Weaknesses in Incident Response Plans?

Many well-intentioned plans appear robust on paper but fail under the pressure of a real crisis. This failure can typically be traced to a few common, avoidable mistakes. Understanding these pitfalls is the first step toward ensuring a plan is operationally viable.

Key weaknesses to avoid include:

• Failure to define an “incident.” Without clear definitions and a severity classification matrix, the team is left to guess when to activate the plan, leading to costly delays.

• Absence of secure, out-of-band communication channels. If primary communication systems like email or Slack are compromised, the response team must have a pre-established, independent channel to coordinate its actions.

• Omission of key third parties. Your Managed Service Provider (MSP), cloud provider, and external legal counsel are integral parts of the response ecosystem. They must be explicitly included in the plan with their roles defined.

• Overly technical documentation. The executive team, communications lead, and legal counsel all have critical roles during an incident. If the plan is not comprehensible to non-technical stakeholders, they cannot perform their duties effectively.

How Can a Small Business Create an IRP with a Limited Budget?

For small and medium-sized businesses, the guiding principles should be simplicity, focus, and practicality. A complex, enterprise-grade plan is unnecessary and likely to be ignored.

Begin by developing a simple plan that addresses the two most probable and high-impact scenarios: ransomware and business email compromise (BEC). Numerous reputable, free templates are available that provide an excellent starting point.

Limited budget should be allocated strategically. Engaging external expertise for high-value activities, such as utilising a virtual CISO (vCISO) service to guide the initial plan development and facilitate the first tabletop exercise, often delivers a significant return on investment.

A simple, tested plan that the team can execute effectively is infinitely more valuable than a comprehensive document that remains unread.

A resilient and audit-ready computer incident response plan is a cornerstone of modern cyber defence. At CyberPulse, our specialists help Australian organisations transition from reactive fire-fighting to proactive preparedness with tailored strategies and continuous validation. Build a security program that protects your business and accelerates your growth by visiting us at https://www.cyberpulse.com.au.