A swift response to a cybersecurity breach can be the difference between a minor disruption and a major outage. In today’s landscape, understanding how to contain a cyber incident is key for any organisation protecting sensitive data and systems.
But what is cyber incident containment?
And what does it involve?
Put simply, incident response is the process of isolating and controlling a security breach to prevent further damage, minimise impact, and maintain business continuity.
In this guide, we’ll run through the core principles of effective containment, the processes involved, and real-world tactics used by leading cybersecurity teams to stay ahead of threats. Ready to strengthen your incident response capabilities? Read on to gain practical insights you can apply immediately.
Looking for expert guidance on building or testing your response plan? Contact NormCyber for bespoke support from our incident response specialists.
What is Containment in Incident Response?
Incident response containment is one of the most vital and complex phases in the incident response lifecycle. It refers to a deliberate set of actions taken to limit the scope and impact of a cyberattack within a digital environment.
For example, if a laptop is infected with malware, shutting it down and disconnecting it from the network is a basic containment action. This prevents the malware from spreading to other systems or communicating with the attacker’s infrastructure.
The primary goals of containment are:
- Prevent the spread of malware or malicious activity.
- Preserve unaffected assets.
- Disrupt the attacker’s ongoing activities (e.g., command-and-control operations).
Failure to contain can lead to data exfiltration, prolonged attacker presence or escalated attacks such as ransomware. That’s why having a clear, structured containment process is essential for effective incident response.
Key Containment Phases in Incident Response Plans
- Communication and Coordination
Effective containment begins with clear and timely communication between internal stakeholders and external partners, like incident response providers or law enforcement. If required, ensure the regulatory bodies and affected customers are kept updated. This first stage is critical. In high-pressure scenarios, alignment and coordinated action are critical to minimising damage and maintaining trust.
- Initial Assessment
The next step involves understanding the scope of the incident. Before taking action, responders need to assess which systems are affected and what’s at immediate risk. A thorough assessment makes sure that containment measures are focused and don’t disrupt key business operations.
Identify the scope of impact by:
- Mapping infected systems.
- Evaluating the attacker’s access level
- Understanding business-critical systems.
Use the MITRE ATT&CK framework to analyse attacker tactics, helping you anticipate their next moves and tailor your response accordingly.
- Isolation of Infection Points
Once the initial assessment is complete, the next priority is to contain the threat by isolating the affected systems. This helps prevent lateral movement and stops the attacker from further breaching your infrastructure. Common isolation activities include:
- Disabling network connectivity or specific ports
- Powering down or disconnecting compromised endpoints
- Locking or disabling compromised user accounts
Isolation should be swift and precise to minimise the threat of spreads. Coordination with IT and business units is key to balancing containment with continuity.
- Implement Additional Controls
To limit further exposure, deploy temporary security measures that harden your systems against continued attacker activity. Examples include:
- Applying temporary firewall rules to block malicious traffic
- Segregating affected networks or systems to prevent lateral movement
- Enabling enhanced logging and monitoring for suspicious activity
- Strengthening endpoint detection and response (EDR) configurations
While these controls are critical, take care to avoid disrupting forensic investigations. Ensure any changes preserve the integrity of digital evidence and maintain a clear chain of custody to support post-incident analysis or legal action.
- Monitoring and Re-Assessment
Containment isn’t a one-time action. It’s an ongoing process that evolves with the threat landscape. Continuous monitoring is essential to detect new indicators of compromise or attacker activity. As part of your efforts, use SIEM platforms (e.g., Splunk) to monitor new anomalies and reassess containment boundaries based on threat evolution. This ensures your response stays aligned with real-time conditions.
Containment Strategies for Incident Response
Choosing the right containment strategy depends on a few factors, such as the nature of the threat and your organisation’s risk tolerance. With this in mind, here are three containment strategies – ranging from aggressive, full isolation to more targeted methods.
All internet access should be blocked to prevent external communication. Disable all user accounts except for those required by emergency administrators. Systems should be recovered locally to minimise external exposure. This approach offers the highest level of security but is also the most disruptive to normal operations.
Allow only approved and secure telemetry connections to maintain visibility without exposing the environment further. Keep clean systems operational to support essential business functions. Internally isolate infected network segments to contain the threat. This approach strikes a balance between security and continuity, making it well-suited for many enterprise environments.
Block only those devices, user accounts, and IP addresses that have been confirmed as compromised. This approach is minimally disruptive to business operations but carries a higher risk if the full scope of the incident is underestimated.
Pro Tip: Use tools like VirusTotal to verify malicious indicators.
Containment Best Practice Recommendations
Effective containment depends on preparation, process and execution. Following a few best practices helps ensure your response is efficient, defensible and aligned with both business and legal priorities.
- Ensure your organisation has a documented incident response plan in place, and run regular tabletop exercises to test and refine it.
- Predefine a containment menu – a set of pre-approved actions that can be deployed quickly depending on incident type and severity.
- Conduct risk assessments for each containment approach, weighing the potential business impact against the need for speed and security.
- Always preserve digital evidence to support forensic analysis and potential legal or regulatory investigations.
- Document every action and decision taken during the incident to ensure transparency, continuity and accountability.
You may also want to refer to the SANS Incident Handler’s Handbook for structured methodologies and proven containment frameworks.
By embedding these practices into your strategy, your team will be better equipped to act decisively under pressure.
Control the Chaos, Contain the Threat
Effective containment is your frontline defence against escalation in a cyber crisis. By following structured stages, choosing the right strategy and integrating best practices, your organisation can stay one step ahead of threat actors.
Ready to review your organisation’s incident containment strategy?
That’s where we come in.
NormCyber is a trusted UK-based cybersecurity provider, offering fully managed cyber defence services to help organisations build resilience against evolving threats. Our incident response specialists work with your team to develop, test and refine response plans that are tailored, effective and regulator-ready. Book a free consultation with us today and ensure you’re prepared before the next breach.
