What is an Incident Response? | A Complete Guide


Incident response, or IR, is an organization’s reaction to an attempted information security breach.

Sixty-five percent of organizations cite fragmented IT and security infrastructure as a key barrier to increasing cyber resilience. While stopping attacks early in the kill chain is critical, organizations must be well-versed in incident response and remediation.

This guide covers incident responses and how to coordinate and expedite incident response processes.

What is an Incident Response (IR)?

Incident response plans usually include a detailed set of activities that provide analysis, detection, and defense, and the effectiveness of the response may affect the integrity of personal and corporate information. A single vulnerability may reveal other organizational weaknesses that become significant factors in a response.

The lessons learned from an attempted breach can measure the efficacy of an organization’s security controls. Mistakes are often the most effective teachers, and learning from them can prevent a recurrence of a security breach.

Incidents may be any occurrence or suspected occurrence of:

  • Hostile actions or a threat of hostile actions intended to affect, damage, or provide unauthorized access to computer systems or computer networks.
  • Threat of, or actual introduction, implantation, or spread of a corrupting, harmful, or otherwise unauthorized piece of code that can infiltrate computer systems.
  • An attack on a computer system or network may result in the degradation or loss of proprietary information or quality of service.

What are Incident Response Firms?

Incident response firms are companies that specialize in helping organizations respond to and manage the aftermath of a security breach or cyber attack. These firms typically have teams of security experts who can assist with a wide range of services, including conducting forensic investigations to determine the scope and nature of the attack, providing guidance on how to secure the affected systems and prevent future attacks, and working with law enforcement to help bring the perpetrators to justice. Incident response firms can also help organizations develop and implement incident response plans, which outline the steps to take in the event of a security breach. These plans are essential for ensuring that organizations can quickly and effectively respond to cyber attacks and minimize the damage they cause.

What is an Incident Response Plan?

According to the National Institute of Standards and Technology, an incident response plan:

Establishes procedures to address cyber attacks against an organization’s information system(s). These procedures are designed to enable security personnel to identify, mitigate, and recover from malicious computer incidents, such as unauthorized access to a system or data, denial of service, or unauthorized changes to system hardware, software, or data (e.g., malicious logic, such as a virus, worm, or Trojan horse).

IR plans typically include incident scoping and investigation, containment, eradication, malware analysis, incident documentation, and transitioning incident details to additional designated incident response partners.

An IR plan usually documents the responsibilities of people, processes, and technology, using this documentation to prepare security personnel for responding to various cybersecurity incidents.

Why You Need an Incident Response Plan

For many organizations, the marked increase in frequency of ransomware and other destructive malware attacks often requires security and IT teams to work in tandem to stop attacks before they progress and potentially cause damage.

However, security teams often struggle with too many tools, too many alerts, and not enough resources to address every threat. Meanwhile, IT teams can lack visibility into the actions security teams perform on the endpoints, cloud workloads, and IoT devices they maintain.

An incident response plan can provide a systematic approach to handling such cybersecurity incidents. A practical IR framework guides organizations through identifying and containing a cyber intrusion while minimizing the cost.

To reduce the consequences of such an attack, cyber incident response procedures are often coordinated closely with contingency solutions, including:

  • Storing backups offsite/alternate site
  • Standardizing hardware, software, and peripherals
  • Coordinating with security policies and controls
  • Minimizing data on client systems
  • Automating backup of data
  • Developing and providing guidance on backing up dataƒ
  • Storing backup information at an alternate site

While contingency planning helps recover the operation of designated information systems at an existing or new location in an emergency, incident response planning typically focuses on the entirety of a security incident, including detection, response, and recovery.

An effective IR is often successfully implemented through an Extended Detection Response (XDR) security and data platform. These platforms offer proactive approaches to new threats, respond without human intervention, have multisite and multi-tenancy flexibility, and provide visibility from a unified standpoint.

With a single pool of raw data comprising information from the entire ecosystem, XDR aims to allow faster, deeper, and more effective threat detection and response, collecting and collating data from a broader range of sources.

Incident Response Steps

A systematic approach to managing a cyber attack can guide organizations through an otherwise catastrophic event and prevent future attacks. Here are the typical steps involved in incident response:

1. Preparation

Preparing against a cyberattack typically requires:

  • Identifying a security team of critical people and developing a written set of an organization’s information security policies.
  • Ensuring everyone understands their roles and responsibilities in an IR plan.
  • Creating a list of assets, including the people, processes, and technology that ensure the success of a critical project.
  • Gathering contact information for key personnel provides immediate access when a cyber event occurs.

2. Detection

Recognizing malicious activity can include:

  • Assessing system data to determine whether a cyber intrusion occurred. Not every anomaly in computer system behavior indicates a cyber issue, which makes identification a crucial decision point.
  • Responding promptly to system error messages, firewall alerts, and log files indicating a cyber attack.
  • Notifying security teams assigned to handle incidents immediately so they can implement the IR plan’s next steps as quickly as possible.

3. Identification

Identifying security incidents for response often requires:

  • Training both security and non-security teams to quickly identify a variety of dynamic threats, including:
    • Phishing: A social engineering tactic used to manipulate users into clicking a malicious link or downloading a malicious file via email
    • Man-in-the-middle (MITM) attacks: Cyber attacks wherein an invisible, malicious actor sits between or facilitates communication between two unaware individuals, skimming sensitive information contained within
    • Trojans: Viruses that look like reliable software to users, tricking them into downloading and installing malicious files that invade systems
    • Ransomware: This type of malware blocks access or encrypts assets, often forcing the user to pay ransom to regain access to their device, files, or system. In many cases, paying ransom to malicious actors doesn’t help. Although payment has been made, users may still be unable to gain access to their files. Some data extortionists now demand a ransom in return for not leaking the user’s data. Today’s ransomware actors have turned toward data theft instead of time-expensive encryption, and importantly, the anatomy of modern extortion attacks involves operators taking different approaches to data destruction from full encryption to partial encryption to no encryption – and, thus, no ransomware – at all.
    • Denial-of-Service (DoS) attacks: Cyber attacks designed to shut down machines or networks by flooding targets with traffic or sending information that triggers a crash, making them inaccessible to intended users
  • Protecting the organization against the above and other constant threats to the security of data and financial information

Organizations often face a constant threat to the security of data and financial information. Incident response examples may be malware that installs viruses such as Trojans, worms, adware, spyware, and ransomware.

4. Containment

Once a threat is detected and identified, containing it involves:

  • Determining the threat’s size and scope.
  • Implementing containment measures to prevent the threat from spreading and creating an additional impact on data systems.
  • Establishing boundaries around the existing damage to prevent more destruction and loss of data.
  • Avoiding mistakes that can erase evidence.
  • Addressing areas most likely to suffer from a cyber attack via:
  1. Short-term containment: This is intended to curtail damage immediately. Identifying infected machines and removing them from a system network can quickly prevent spread. In some cases, promptly addressing containment issues may require disabling an organization’s servers until a damage assessment can define further actions.
  2. Long-term containment: Long-term containment addresses lingering effects after the initial onset of an attack. For example, while security teams fix infected systems and prepare them for service, backups or additional equipment can help organizations maintain business continuity while vulnerabilities are patched or removed.
  3. Continuous monitoring: Monitoring software can provide ongoing visibility into an organization’s information systems, providing information about when and where attacks occur. This helps security teams patch existing vulnerabilities, identify new vulnerabilities in real time, and in some cases, predict where future intrusions might occur.

5. Eradication

Eliminating all traces of contamination from a security intrusion often requires:

  • Thoroughly inspecting all systems to ensure the eradication of vulnerabilities.
  • Documenting all research efforts to provide stakeholders with critical information for informing future incident response guides.
  • Creating a detailed account of the breach and assessing the impact of the incident, including data on resources spent on remediation efforts.
  • Improving security defenses and eliminating vulnerabilities.
  • Informing decision makers with all the necessary data for choosing a well-informed path using best practices.
  • Planning for undetected artifacts, which can cause reinfection and require repeating the steps in an IR framework.

6. Recovery and Restoration

Returning to business as usual after an attack can include:

  • Removing malicious content from infected systems
  • Rechecking, testing, and verifying all components for functionality
  • Enacting extreme care during the recovery and restoration process so information systems are reliable once more
  • Implementing a systematic approach to testing, monitoring, and validating data systems to avoid future compromise
  • Designing procedures that help return information systems to full functionality (e.g., establishing an agreed-upon timeframe to restore data systems for use)
  • Creating a written record of platforms and processes for testing and verification of restored systems to provide guidelines for managing another intrusion should it occur

Build an Incident Response Plan with SentinelOne

Standardized software that can coordinate and expedite incident response processes may help both security and IT teams better respond to security incidents. Most organizations stand to benefit from an Extended Detection Response (XDR) security and data platform that can ingest data at scale, perform AI-powered analytics, centralize security incident response, and interconnect IT and security platforms for autonomous response capabilities.

SentinelOne provides AI-powered prevention, detection, and response across endpoints, cloud workloads, and IoT devices to stop and prevent incident responses. When corrective action needs to occur, SentinelOne can kill, quarantine, remediate or roll back any potential effects from the threat.

And this all happens at an enterprise scale with precise, context-driven decisions autonomously, at machine speed — without human intervention.

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