In digital forensics and incident response (DFIR), scoping is one of the first steps when tackling an incident. It sets the groundwork for the investigation by identifying the user accounts, systems, and data that may be affected, while helping ensure the right resources are in place at the right time.

Proper scoping helps avoid two problems: underestimating the incident, which can leave gaps in the investigation, and overestimating it, which can waste valuable time and resources.

When done correctly, scoping allows responders to work efficiently, contain the incident, and shorten recovery time. The goal is to understand the incident early enough to determine how far an attacker may have gotten, what is at risk, and whether the activity is still ongoing.

With that understanding, responders can focus their efforts on the systems, accounts, data, and vulnerabilities that matter most.

Elements of Effective Scoping

Conducting a thorough and accurate scope involves several key steps. The first is gathering as much information as possible about the nature of the incident.

Useful starting points may include:

• Interviews with management, IT personnel, users, and others who may have information about what occurred.
• Initial triage of available logs, including web logs, Windows Event Logs, syslogs, authentication logs, and other relevant sources.
• Identification of system assets and the organization’s network topology.
• EDR, SIEM, antivirus, and other security alerts.
• Threat intelligence and other security information related to the incident.
• Historical security issues, previous compromises, or other activity that may provide useful context.

Based on the information gathered, the team must begin determining which systems, accounts, and data are potentially affected.

This may involve mapping compromised systems, reviewing network topology, identifying affected users, and determining the possible entry points an attacker used to gain access.

Understand the Attacker’s Activity

Another important part of scoping is evaluating the attacker’s tactics, techniques, and procedures (TTPs).

Understanding how the attacker operates can help responders determine where else to look. If the activity suggests credential theft, lateral movement, persistence, or data exfiltration, the scope may need to include additional systems and data sources capable of providing evidence of those actions.

The scoping process should also include a review of the timeline. Responders need to determine when the activity may have started, how long the attacker may have had access, and what occurred during that period.

Work in Parallel

Remember to multitask. You do not need to wait for one stage of the investigation to completely finish before beginning another. Work in parallel whenever your available resources allow it.

For example, during scoping you may identify that a particular user’s account was used during the attack. Instead of waiting until the entire scoping process is complete, another team member can immediately begin investigating that account.

Later, you may learn that company data has appeared on the dark web. That information should cause the investigation to pivot. Identify where that data existed within the environment and begin acquisition or analysis of the relevant systems while the rest of the scoping effort continues.

Tools and Techniques for Scoping

Effective scoping relies on both methodology and the tools available within the environment.

Endpoint detection and response (EDR) platforms can provide visibility into activity occurring across individual endpoints. When already deployed, this can allow responders to search a large number of systems quickly for processes, files, network connections, alerts, and other activity related to the incident.

Network traffic analysis can also help identify unusual communications between systems that may indicate lateral movement, command-and-control activity, or data exfiltration.

Combining endpoint and network information with centralized log management or SIEM platforms can give responders a broader view of what occurred across the environment.

Forensic analysis tools can then be used to examine compromised systems more deeply. This may include collecting and analyzing memory, filesystem data, forensic disk images, operating system artifacts, logs, and other evidence.

This information can help responders correlate suspicious behavior across multiple evidence sources, identify indicators related to the attack, and eventually work toward understanding the attacker’s actions and the root cause of the incident.

Scope Creep

Scope creep occurs when additional tasks, systems, accounts, analysis, or investigative areas are added beyond the original scope of the incident without enough assessment or justification.

This can happen naturally as new evidence or leads emerge. It can also happen when stakeholders request additional systems, accounts, or data to be examined simply because an investigation is already underway.

Some changes to scope are absolutely necessary. An investigation should change when the evidence supports that change.

The problem is unchecked scope creep.

Continually expanding an investigation without considering the relevance of new work can overwhelm responders, delay containment and recovery, consume unnecessary resources, and divert attention away from the incident itself.

An Example of Scope Creep

Imagine you are responding to a suspected ransomware attack.

The initial scope is focused on investigating compromised servers, identifying the ransomware, determining the extent of encryption, and understanding how the attacker gained access to the environment.

During the investigation, you identify a system where a user has been emailing confidential company data to a personal email account.

That discovery may be important. It may represent an insider threat, a policy violation, or another issue that eventually requires investigation.

But is it related to the ransomware incident?

If there is no evidence connecting the user’s activity to the ransomware attack, document the finding and make sure the appropriate people are aware of it. Do not automatically redirect the ransomware investigation down an unrelated path.

If later evidence establishes a connection between the user’s activity and the incident, then the scope should change.

Controlling the Scope

To avoid unnecessary scope creep, establish a well-defined and agreed-upon scope as early in the investigation as practical.

That does not mean the initial scope can never change. In fact, it probably will.

Any significant change should be evaluated against the evidence, the potential impact on the investigation timeline, available resources, and the risk of not pursuing that lead.

Clear communication with stakeholders is also important. Requests for additional analysis should be prioritized based on their relevance to the incident rather than simply added to an ever-growing list of investigative tasks.

By maintaining control over the scope while remaining willing to adjust it when the evidence supports doing so, responders can stay focused on resolving the incident without ignoring important new information.

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Conclusion

Good scoping gives the rest of the investigation direction. It helps identify the systems, accounts, data, and evidence sources that matter while allowing responders to prioritize limited time and resources.

Start by gathering what is known. Talk to the people involved, review the available logs and alerts, understand the environment, identify potentially affected systems and accounts, and begin building a timeline of the attacker’s activity.

Most importantly, remember that scope is not static. As new evidence is collected and analyzed, your understanding of the incident will change. When the evidence points somewhere new, follow it. When something is unrelated to the incident, document it and avoid letting it pull the investigation off course.

The goal is not to investigate everything. The goal is to investigate enough of the right things to understand what happened, contain the threat, and determine what needs to happen next.