Knowledge What Is EDR? Easy-to-Understand Explanation of How It Works, Its Features, and How It Differs from Antivirus

EDR (Endpoint Detection and Response) is a security solution that monitors devices located at the endpoints of a network—such as PCs, servers, and smartphones—detects signs of cyberattacks, and supports rapid response. Since traditional measures focused on preventing intrusion can sometimes be insufficient, EDR is characterized by assuming that intrusions will occur and focusing on detection and response after a threat has already entered the environment.

EDR operates by installing dedicated software called an “agent” on each endpoint. This agent continuously collects logs of all activity occurring on the device—such as file operations, process execution, and network communications—and sends them to a management server in the cloud or on-premises. On the management server, the vast amount of collected log data is analyzed using AI and machine learning, and the system is monitored in real time for suspicious behavior or signs of attack. When a threat is detected, security administrators are promptly notified, allowing them to immediately perform actions such as isolation and investigation.

Traditional security measures have mainly relied on “perimeter defense”, which protects the boundary between the internal network and the outside world using firewalls and similar tools. However, with the spread of remote work and the increased use of cloud services, the boundary between inside and outside the company has become blurred. Attackers are also using methods that are difficult for traditional defenses to detect, such as “fileless attacks” that abuse legitimate OS tools. Against this backdrop, the recognition has grown that it is impossible to prevent intrusions completely, and the need for EDR—which quickly detects threats after intrusion and minimizes damage—is increasing.

EDR provides various functions to smoothly manage everything from cyberattack detection to response and recovery. Below are three core functions.

EDR’s most fundamental function is the continuous monitoring of endpoint activities and ongoing collection of operation logs. It records a wide range of data, including process execution, file access, registry changes, and network communications. This allows organizations to accurately understand the full picture of an attack when an incident occurs and secure essential information for root-cause analysis.

The collected log data is analyzed in real time by an analysis engine in the cloud or on-premises. EDR does not just look for known attack patterns; it also uses AI and behavioral detection technologies to identify suspicious activities that differ from normal behavior. For example, it can detect anomalies such as system commands not used in normal business operations being executed or a large number of files being encrypted in a short period of time, as well as credentials being harvested, and promptly alert security administrators. This enables early detection of attacks and minimization of damage.

When a threat is detected, EDR provides features that support rapid response. From the management console, administrators can isolate endpoints suspected of being infected from the network to prevent further spread of damage. They can also remotely stop malicious processes, restore modified registry entries, or delete the files that caused the incident. As a result, the time required for incident response can be significantly reduced and the impact on business operations minimized.

EDR is often compared with EPP (Endpoint Protection Platform). EPP is a comprehensive endpoint protection solution centered on antivirus. While both aim to protect endpoints, their roles and approaches differ significantly.

The primary goal of EPP is to prevent threats from entering the endpoint. It blocks intrusion at the perimeter by comparing files against pattern files of known viruses or detecting malware-like behavior from program actions. EDR, on the other hand, is intended for post-intrusion response to threats that EPP could not fully block. It detects intruded threats as early as possible and responds quickly to minimize damage.

Since EPP is based on pattern matching, it offers strong protection against known malware. However, it is difficult to completely prevent unknown threats such as newly created malware and their variants, fileless attacks that exploit legitimate OS functions, and zero-day attacks. In contrast, EDR constantly monitors the behavior of the entire endpoint—not just individual programs—giving it strength in detecting unknown threats and sophisticated cyberattacks. This makes it possible to respond quickly even to attacks that traditional EPP cannot fully prevent.

When EPP blocks a threat, it notifies the user, but the logged information is basic and its capabilities for detailed investigation—such as why the attack occurred and whether there are other impacts—are limited. EDR, by contrast, provides detailed logs and analytical information to support identifying the intrusion path, scope of impact, and root cause after detecting a threat. This allows administrators to grasp the full picture of the incident and carry out more effective containment and rapid recovery.

By implementing EDR, companies can strengthen their post-intrusion response capabilities and significantly improve their security posture. Here are three main benefits.

The greatest benefit of EDR is its ability to quickly identify cyber incidents and respond rapidly. Because EDR constantly monitors endpoint behavior, it can detect threats at an early stage—soon after threats that EPP could not fully stop begin to act. After detection, features such as remote endpoint isolation and process termination allow you to respond before damage spreads, minimizing the impact on business operations.

In the event of an incident, the detailed log data collected and recorded by EDR becomes a vital source of information for uncovering the full extent of the damage. It visualizes the entire attack, including which endpoint was first compromised, which endpoints the infection spread to, and what information was targeted. This prevents gaps in response and makes it easier to identify root causes and implement recurrence-prevention measures.

Another major benefit is the ability to handle advanced threats that are difficult for traditional antivirus software to detect, such as unknown malware, fileless attacks, and zero-day attacks. EDR analyzes not only static properties of individual files but also sequences of behaviors and relationships between processes in real time. This allows it to detect sophisticated attacks that disguise themselves as legitimate operations, for example by abusing standard OS tools.

While EDR is a powerful security solution, there are some challenges and points to be aware of when implementing it. To ensure a successful implementation, it is important to properly understand these considerations and plan countermeasures in advance.

When EDR detects a threat, it generates an alert, but humans must ultimately decide whether the alert is truly dangerous and what actions to take. Correctly analyzing the alert content and issuing appropriate instructions requires advanced knowledge and experience in cybersecurity. If your organization lacks in-house specialists, using an MDR (Managed Detection and Response) service that outsources EDR operations externally can be an effective option.

Introducing EDR requires license fees and, in the case of on-premises deployments, costs for servers to store and analyze logs. In general, it tends to be more expensive than EPP (antivirus software). As mentioned above, securing specialized personnel or using MDR services also incurs additional costs. You should carefully consider cost-effectiveness and select products and services that match your security budget and operational structure.

Because EDR is highly sensitive, it can sometimes mistakenly flag legitimate behavior as “suspicious activity” (over-detection / false positives). If over-detection occurs frequently, security staff will be forced to investigate each case, leading to a significant increase in operational workload and a higher risk of missing truly dangerous alerts. Before implementation, it is important to check each product’s detection accuracy and the flexibility of its tuning features, and to establish settings and operational processes that minimize over-detection.

There are many EDR products on the market, each with its own characteristics. Here are three key points for selecting the EDR product that best suits your organization.

The core of EDR is how accurately it can detect threats. Confirm whether it has sufficient capability to detect the attack scenarios you care about, such as unknown threats and fileless attacks. As mentioned earlier, a low rate of over-detection is also important. It is recommended to refer to reports from independent evaluation organizations (e.g., AV-Comparatives, MITRE ATT&CK Evaluations) and to conduct a Proof of Concept (PoC) in your own environment to objectively evaluate detection accuracy.

Operating EDR requires specialized knowledge, but usability of the management console and richness of analysis support features vary by product. Select a product from the perspective of whether your security staff can operate it continuously without undue burden, given their skill levels. For example, features that automatically rate the severity of detected threats or suggest recommended response actions can help reduce operational workload. If you lack in-house experts, choosing a product that comes bundled with an MDR (managed detection and response) service can also be effective.

In the event of a serious incident, the support you can receive from the vendor is extremely important. Check whether they can handle inquiries in the necessary language, whether a 24/7 support desk is available, and whether experts can provide analytical support during incidents. Availability of support offerings such as assistance with initial setup at deployment and regular operational training are also important factors when selecting a product.

There are several related terms that frequently appear when discussing EDR. Here, we explain how the representative terms “XDR” and “SIEM” differ from and relate to EDR.

XDR is a broader detection and response solution that encompasses EDR. While EDR focuses only on information from endpoints, XDR additionally collects logs from a wider range of areas—such as network devices, cloud services, email, and user authentication—and analyzes them across these layers. This makes it easier to understand the overall picture of sophisticated attacks that span multiple systems and are difficult to detect with a single solution.

SIEM is a system that centrally collects and manages logs from a wide variety of IT devices and systems within an organization—such as firewalls, proxy servers, and business applications—in order to detect anomalies. While EDR deals with “deep” information from endpoints, SIEM handles “broad” information across the entire organization. By integrating EDR with SIEM, suspicious behavior detected on endpoints can be correlated with organization-wide logs, enabling higher-precision threat detection and faster incident response.

This article has provided a comprehensive explanation of EDR—from its basic concepts and mechanisms to how it differs from traditional measures, the pros and cons of implementation, and how to choose a product. In today’s environment of increasingly sophisticated cyberattacks, EDR, which assumes that intrusions will occur and focuses on post-intrusion measures, is a crucial element for strengthening a company’s security posture. By accurately understanding your organization’s situation and using the points introduced here as a reference, consider implementing the EDR solution that best fits your needs.

KDDI offers deployment and operational support services for “CrowdStrike”, which integrates next-generation antivirus and EDR capabilities. With expert monitoring and operations 24 hours a day, 365 days a year, it helps reduce the burden on your internal security team.