What is Digital Forensics and Incident Response (DFIR)?

Digital Forensics and Incident Response (DFIR) is a practice used by incident response teams (also known as computer security incident response teams or CSIRT) to detect, investigate, and respond to cyber threats facing an organization.

A core part of DFIR is digital forensics — collecting data from IT systems, including operating systems, file systems, and hardware, analyzing it, and reconstructing it for use as evidence in the incident response process. Increasingly, DFIR is being used beyond CSIRT teams, and forensic investigation practices are adopted for additional activities like remote investigation of endpoints and proactive threat hunting.

Why is DFIR Important in Cybersecurity?

When a cyber attack occurs, the first priority is recovering from the incident. But recovery is not enough, because in order to fully eradicate the threat, and prevent it from recurring, organizations need to understand what happened and who was behind the attack.

DFIR provides a deep understanding of cybersecurity incidents through a comprehensive forensic process. DFIR experts gather and investigate vast amounts of data to fill in gaps of information about cyber attacks, such as who were the attackers, how they broke in, and the exact steps they took to place systems at risk. In the event of a successful breach, DFIR can also help identify the data lost or exact damage caused.

Digital forensic information collected by DFIR experts is frequently used to file lawsuits against identified attackers. It is also commonly used by law enforcement, and can be used as evidence in court proceedings against cybercriminals.

How is Digital Forensics Used in Incident Response?

Some organizations leverage DFIR as an outsourced service, while others build a DFIR capability in-house. In both cases, the DFIR team is responsible for identifying cyber attacks, triaging them to determine their nature and extent, and gathering actionable data to assist with response. The DFIR function performs several critical steps as part of an organization’s incident response process.

DFIR capabilities typically include:

• Forensic collection—gathering, examining, and analyzing data from networks, applications, data stores, and endpoints, both on-premises and in the cloud.

• Triage and investigation—determining whether the organization has been breached and identifying the root cause, scope, timeline, and impact of the incident.

• Notification and reporting—depending on the organization’s compliance obligations, there may be a need to notify and report on breaches to compliance bodies. In addition, depending on the severity of the incident, there may be a need to notify authorities like the FBI and Cybersecurity and Infrastructure Security Agency (CISA) in the US.

• Incident follow up—depending on the nature of the incident, there may be a need to negotiate with attackers, communicate incident status to stakeholders, customers, and the press, and make changes to systems and processes to address vulnerabilities.

The goals of DFIR as part of the incident response process include:

• Responding to incidents as quickly and accurately as possible.

• Following an efficient, consistent process to investigate incidents

• Minimize damage to the organization, including data loss, damage to organizational systems, business disruption, compliance risks, and damage to reputation.

• Improve the organization’s understanding of its threat landscape and attack surfaces.

• Rapidly and fully recover from security incidents, identifying the root cause and eradicating the threat across all organizational systems.

• Enable effective prosecution of attackers by law authorities, and provide evidence for legal actions taken by the organization.

What is the Difference Between Incident Response and Computer Forensics?

Incident response and computer or cyber forensics both deal with the same issue; they are responses to a compromise, breach, or attack. Incident response is focused on the containment of a threat or attack. Forensics involves a thorough examination of the data in order to gain a complete understanding of the breach in order to remediate the attack and prevent a recurrence.

Incident Response

Incident response consists of actions taken immediately following a security compromise, attack, or breach. In addition to containing the attack, responders must also preserve all relevant evidence for later examination. This requires a team of experienced professionals who understand how to respond to the incident while carefully preserving evidence.

Attempting to restore or recover information from a compromised computer or network could cause irreparable damage to files or the system. A dedicated, professional incident response team can handle even the most complex breach events with precision and speed, placing your organization in the best position to mitigate loss and keep the business operational.

Digital Forensics

Following an attack, there are two important questions to answer: “how did it happen?” and “how to prevent it from happening again?” Digital forensics is the process by which experts collect, examine, and analyze data from compromised computer systems and storage devices in order to answer these questions. This is done carefully, following professional best practices, to ensure that the evidence could be admissible in a court of law if necessary.

Evidence collection includes identifying and securing infected devices and all data, including latent data, from the systems. Latent or ambient data is data that is not easily accessible (it could be hidden or deleted) and requires an expert to uncover. Once the evidence is collected and evaluated, it undergoes a detailed analysis to determine root cause, scope of breach, and what data may have been impacted. Each step of this process is carefully documented.

DFIR and SOAR

Security orchestration, automation, and response (SOAR) technologies can autonomously identify security incidents and respond to them. SOAR solutions leverage machine learning to analyze security events, and can automate complex security processes to respond to them. To this end, they integrate with other security tools such as firewalls and endpoint security.

DFIR experts and service providers are commonly responsible for incident response in an organization. SOAR is an extension of the DFIR role, making it possible to automate response for many types of incidents, augmenting the work of DFIR analysts. With cyber attacks growing in volume and sophistication, this can be very important to ensure full incident coverage and timely response. SOAR can also reduce human error in the DFIR process.

DFIR experts can work alongside SOAR systems. SOAR solutions can respond to clear-cut incidents that can easily be detected and have established response playbooks. This reduces manual work for DFIR experts, allowing them to focus their time on threat hunting, investigation and response of complex threats that cannot be automatically detected.

Related content: Read our guide to digital forensics tools

How to Choose DFIR Services

When evaluating a DFIR service provider, consider the following:

• Forensic capabilities—evaluate the service provider’s process when handling forensic evidence, and their use of facilities and tools like clean rooms, forensic laboratories, specialized storage systems, and eDiscovery tools.

• DFIR experts—evaluate the qualifications and experience of consultants or incident responders employed by the service provider.

• Vertical and industry expertise—ensure that the service provider has a proven track record of serving companies similar to your own, with the same organizational structure and operating in the same industry.

• Geographic coverage—for global organizations, it is important that the DFIR service can operate in multiple countries. In many cases DFIR requires on-site presence at local facilities.

• Scope of service—DFIR services can be proactive or reactive. Proactive services include activities like threat hunting, vulnerability testing and security education. Reactive services include incident response and attack investigation.

• Pricing—many DFIR service providers offer a prepaid subscription-based service. If an organization does not use all consulting hours, for example due to fewer security incidents in a given period, they can use the hours to prepare for security incidents, for example by performing tabletop exercises with leaders and executives.