In digital forensics and incident response (DFIR), scoping is your first step when tackling an incident. It sets the groundwork for the entire investigation by identifying the user accounts, systems, and data that may be affected, and helps make sure you have the right resources in place at the right time. Proper scoping is key to avoiding underestimating, which can leave gaps in the investigation, or overestimating it, leading to wasted time and resources. When done correctly, it allows responders to work efficiently, contain the incident, and shorten recovery time. It’s all about understanding the scope of the breach early on to figure out how far the attacker has gotten, what’s at risk, and whether the breach is ongoing so that efforts are focused on the right systems and vulnerabilities. This way, further damage can be prevented, and the incident can be addressed quickly and thoroughly.
Elements of Effective Scoping
Conducting a thorough and accurate scoping involves several key steps.
- Incident responders must gather as much information as possible about the nature of the attack. This typically involves:
- Interviews starting with open ended questions “Tell me what happened” (management, IT, users)
- Initial triage of logs (web logs, event logs, syslogs etc)
- Identify system assets and network topology
- EDR/SIEM/AV Alerts
- Other security intelligence data to understand what is known about the incident.
- Historical issues / breaches
- Based on the above information the team must determine which systems and data are potentially affected. This might involve mapping out the compromised systems, reviewing network topologies, and identifying all entry points where the attacker may have gained access.
Another vital element is evaluating the attacker’s tactics, techniques, and procedures (TTPs). Understanding these details helps in estimating the level of sophistication of the attack and predicting how far the breach might have spread. The scoping process should also include a timeline review to ascertain when the attack started and how long the attacker may have had access. Remember to multitask! You do not need to wait for any stage to complete before going to the next. Work in parallel as much as you can.
Example, during scoping you identify X user’s account was utilized during the attack. Immediately have someone else from the team start digging into that account. Later on in scoping, you find out that Y data was identified on the dark web by the victim. Pivot your scoping to identifying what system that data exists in their environment and have another team member being acquisition / analysis of that system.
Tools and Techniques for Scoping
Effective scoping relies on the right tools and methodologies. One commonly used approach is the deployment of endpoint detection and response (EDR) solutions (if not already deployed), which can provide deep visibility into what is happening on individual endpoints across the organization. Network traffic analysis tools also play a vital role by helping to detect abnormal communications between systems that might indicate lateral movement or exfiltration of data. Combining these tools with centralized log management systems like SIEM (Security Information and Event Management) solutions allows responders to get a holistic view of the attack. Take not these tools are nice to have and will assist you with working at scale, but are not required. You can fully conduct an investigation without them, but the process will become more manual.
Additionally, forensic analysis tools can be used to examine compromised systems more deeply, capturing evidence such as memory dumps, file system data, and disk images. This evidence helps responders correlate suspicious behavior to specific indicators of compromise (IOCs) and identify the root cause of the attack. I will cover this more in another post.
Scope Creep
Scope creep occurs when additional tasks, analysis, or investigation areas are added beyond the original scope of the incident, often without proper assessment or justification. This can happen when new evidence or leads emerge, or when stakeholders request more systems, accounts, or data to be investigated than initially planned. While these additions may seem necessary in the moment, unchecked scope creep can overwhelm responders, delay containment and recovery efforts, and lead to unnecessary use of resources, potentially diverting focus from critical areas. In the fast-paced world of DFIR, where time is of the essence, scope creep can significantly hinder the effectiveness and efficiency of the response.
An example of scope creep is you are responding to a suspected ransomware attack. Initially, the scope is focused on investigating specific compromised servers, identifying the ransomware variant, and determining the extent of the data encryption. But as the investigation progresses you identify a system where the user has been emailing confidential company data to their personal email account. Now this could be related, but if I don’t have a link between the ransom attack and this user/emails then I would put it on the list, but not run down that rabbit trail until something guided me down it.
To avoid scope creep in DFIR investigations, it’s essential to establish a well-defined and agreed-upon scope early in the process. Any changes to the scope must be carefully evaluated for their potential impact on the investigation timeline, resource availability, and overall risk. Clear communication with stakeholders is key ensuring that any requests for additional analysis are prioritized based on their relevance to the incident. By maintaining tight control over the scope and adjusting it only when absolutely necessary, responders can stay focused on resolving the incident quickly and thoroughly, without getting sidetracked by less critical issues.