digital forensics and incident response (DFIR)

What is digital forensics and incident response (DFIR)?

Digital forensics and incident response (DFIR) is a combined set of cybersecurity operations that incident response teams use to detect, investigate and respond to cybersecurity events.

As the acronym implies, DFIR integrates digital forensics and incident response processes.

What is digital forensics?

Digital forensics is a subset of forensic science that involves the collection of telemetry, log and observability data from an organization's IT systems, including operating systems, file systems, hardware, applications and endpoints.

The goal of digital forensics is to gather all the data needed to accurately determine what happened during a specific security incident and preserve it as digital evidence. This digital evidence can be used in-house -- for example, to reconstruct a security event or investigate an internal policy violation -- or, externally, as evidence during court cases, litigations and audits.

Digital forensics helps incident responders identify the root cause of an incident, understand how attackers gained access to the system and discern which systems were affected.

Digital forensics is sometimes referred to as computer forensics or cyber forensics. The main difference between these terms and digital forensics is that the latter is generally tied to cybercrime and maintaining the integrity of data collected, while computer and cyber forensics aren't necessarily conducted due to a cybersecurity event, rather they are often used for disaster recovery or troubleshooting operational issues, for example.

What is incident response?

Incident response is the approach an organization takes to respond to and mitigate the effects of a security incident, such as a malware attack or data breach. Effective incident response requires a well-vetted incident response plan, incident response playbooks and a combination of tools to detect, contain and eradicate threats, as well as recover and restore systems.

An incident response team is also referred to as a computer security incident response team (CSIRT), computer incident response team or computer emergency response team (CERT). Many security operations center (SOC) teams also handle incident response processes.

How do DF and IR work together?

In short, digital forensics is concerned with the collection and analysis of data to fully understand what happened in an incident and preserve that data, while incident response is concerned with the remediation of the incident.

The combination of these two separate and distinct sets of operations provides an incident response team an integrated approach, including the data, tools, processes and capabilities needed, to remediate and recover from cyberattacks.

DFIR is often conducted by an in-house incident response team composed of incident responders, security analysts, threat researchers and forensic analysts. Organizations without in-house staff often hire third-party DFIR service providers.

What is the DFIR process?

DFIR integrates the following data forensics and incident response steps and processes:

1. Data collection. Forensic analysts collect and access data from servers and applications -- wherever they are deployed -- to conduct analysis. This includes file system forensics, memory forensics, network forensics and log analysis. Data collection could also include user activity from identity and access management and other systems.
2. Data analysis and correlation. Responders and analysts query log data and correlate events across different systems and applications. Because attacks are commonly composed of multiple actions across systems and users, it's critical to connect data points to fully understand security events.
3. Incident response preparation. Before an incident occurs, incident response teams should write an incident response plan. As part of this, create playbooks to help security teams and other personnel across the organization know the steps to take during specific types of security events, such as a ransomware attack or distributed denial-of-service attack. This step also includes conducting tabletop exercises to test how well the playbooks and incident response plan perform, as well as revising or updating them as necessary.
4. Threat detection and forensic investigation. Threat detection tools, such as endpoint detection and response (EDR), extended detection and response (XDR), and security orchestration and automation (SOAR), help incident response teams discover potential cybersecurity issues. Digital forensics comes into play in this step, providing responders the data and tools needed to understand the events of the attack. Data forensics also enables scoping of the incident to assess the breadth, severity and root cause of the incident.
5. Containment and recovery. Using the insights gained from the previous steps' digital forensics analysis, responders can contain, mitigate and eradicate the threat.
6. Reporting. DFIR benefits from this self-improvement step, which also helps prevent the risk from recurring in the future. Create a post-mortem report to identify what processes worked, what did not work and what can be done better to improve the outcome of future security events.

What are the benefits of DFIR?

The integrated approach of DFIR offers the following benefits:

• Better accuracy. The added information provided by digital forensics enables security teams to have a better, more accurate understanding of an incident by taking into account what happened.
• Improved recovery. DFIR can improve recovery time from security breaches because analysts and responders are prepared to handle incidents and have the proper data and tools in place to do so.
• Minimized disruption. By improving accuracy and recovery times, DFIR can minimize the impact on business operations -- for example, system downtime or data loss.
• Strengthened security posture. DFIR provides responders clear insight into how an attack occurred. This enables security teams to identify and remediate weaknesses and vulnerabilities and thus prevent similar attacks in the future.
• Digital evidence for law enforcement. Accurate data collected and analyzed as part of the DFIR process could be used as evidence, if needed, in support of legal action against cybercriminals.

What are the challenges of DFIR?

While DFIR offers several benefits, keep in mind the following DFIR challenges:

• Massive volumes of data. The DFIR process requires a significant amount of forensic data. This can be difficult to manage, query and maintain.
• Dispersed data. Not only is there a lot of data, but it is often distributed across numerous systems and locations, as well as kept in different formats. Figuring out where all the data is, how to access it and how to correlate it are not simple tasks.
• Evidence preservation. Preserving data that can serve as evidence of attack and maintaining a chain of custody -- a process that records the details about the movement of evidence to ensure data integrity and accuracy -- are challenging.
• Expanding attack surfaces. Organizations and employees use an array of devices and applications that is constantly changing. This growing attack surface is difficult to assess and manage, which can make it difficult to conduct DFIR.
• Talent and staffing issues. Lack of in-house talent with digital forensics expertise, paired with staffing shortages, is a major issue for organizations. Alert overload for already stressed security teams is also a challenge.

How to choose a DFIR tool

Digital forensics and incident response tools are available as platforms organizations can run themselves or buy as managed services, or they can be a combination of existing services and tools.

Selecting the best DFIR approach for an organization's needs is critical to rapidly detect, investigate and recover from cybersecurity incidents.

When selecting a DFIR tool, consider the following key factors:

• Expertise of the DFIR team. If selecting a managed service, look for providers with qualified DFIR experts and incident responders. Breadth and depth of experience with complex investigations and response processes are essential. Experience with similar organizations in the same industry is another positive attribute.
• Proximity and availability. A provider in relative geographic proximity and with resources in the time zone in which the organization operates is beneficial in the event on-site assistance is needed.
• Proactive vs. reactive services. Some DFIR services and tools specialize in proactive threat hunting and assessments, while others focus on reactive incident investigation. Understand the difference between these options, and choose the one best aligned to the organization's use case.
• Forensic capabilities. Assess providers or tools based on their ability to comprehensively gather, preserve and analyze evidence from a distributed set of systems, while still maintaining chain of custody integrity.
• Tool integration. Most organizations already have security tools that conduct threat detection and response, such as EDR, XDR, security information and event management, and SOAR. Ensure any new DFIR tools or services integrate with the organization's existing tools to expedite response and improve data collection.
• Pricing models. DFIR tools and services are offered as prepaid subscriptions, tool licensing and incident-based models. Choose the approach that best fits the needs of the organization, its security team and its budget.