What Is EDR (Endpoint Detection and Response)?

What Is EDR?

Endpoint Detection and Response, or EDR, is a security technology that monitors endpoint activity, detects suspicious behavior, helps analysts investigate attacks, and supports response actions.

Endpoints include laptops, desktops, servers, virtual machines, and workloads that connect to business systems and data. These devices are often where attacks begin. A user may open a phishing attachment, a script may run from a temporary folder, or an attacker may use stolen credentials on a legitimate device.

EDR is designed for the point where prevention alone is not enough. Traditional endpoint protection can block known malware, but attackers do not always rely on known malicious files. They may use legitimate system tools, stolen accounts, fileless techniques, or living-off-the-land methods to avoid basic detection.

EDR gives security teams the endpoint telemetry they need to understand what happened, how far the activity went, and what should be contained first. It helps answer practical incident questions: Which process started the activity? Which account was involved? What command executed? Did the endpoint connect to unknown infrastructure? Did the same behavior appear on other devices?

In simple terms, EDR helps security teams move from alert review to attack understanding.

Why EDR Matters

EDR matters because many attacks become visible through endpoint behavior before they become visible anywhere else.

A firewall may record a network connection. An identity system may confirm a login. Endpoint telemetry adds device-level context: which process ran, which command executed, which file changed, which account was involved, and whether the activity deviates from normal behavior.

This context is critical during an incident. An alert that says “suspicious file detected” rarely gives analysts enough information by itself. The team needs to know how the file arrived, whether it executed, what child processes it created, what registry changes followed, and whether the activity spread to other systems.

EDR also helps detect activity that traditional antivirus may miss. For example, an attacker may use PowerShell to download a payload, dump credentials, or move laterally across the environment. PowerShell itself is a legitimate tool. The risk comes from how it is used.

That changes the detection problem. Security teams need visibility into process lineage, command-line arguments, file operations, registry changes, credential access attempts, and network connections. EDR collects and correlates this activity so analysts can reconstruct the attack path and decide how to respond.

How EDR Works

EDR usually works through an agent installed on each protected endpoint. The agent collects endpoint telemetry and sends it to a central platform for analysis, alerting, investigation, and response.

A typical EDR workflow includes four stages.

1. Continuous Monitoring

EDR continuously records activity from endpoints. This may include process execution, command-line arguments, file creation and modification, registry changes, network connections, user activity, and system events.

This telemetry creates a record of what happened on the endpoint. Without it, analysts may only see the final alert, not the sequence of actions that led to it.

2. Behavioral Detection

EDR uses behavioral analytics, detection rules, threat intelligence, and contextual signals to identify suspicious activity. It looks for signs such as abnormal script execution, suspicious process chains, credential dumping, ransomware-like file changes, privilege escalation, and lateral movement.

The goal is not only to detect known malware. EDR also looks for attacker behavior that may indicate compromise even when no known malicious file is present.

3. Investigation

When EDR detects suspicious activity, analysts use the platform to investigate the event. They may review process trees, timelines, command-line history, file activity, registry changes, user context, network connections, and related activity across other endpoints.

This helps the team answer operational questions. Did the attack start from phishing? Was the device used to access credentials? Did the attacker connect to command-and-control infrastructure? Did the same activity appear on other systems?

A useful EDR investigation does not stop at a single alert. It reconstructs the attack sequence.

4. Response and Containment

EDR supports response actions that help contain and remediate threats. These actions may include isolating an endpoint from the network, killing a malicious process, quarantining a file, blocking an indicator, collecting forensic artifacts, or rolling back malicious changes where supported.

Some actions can be automated based on policy. Others should go through analyst review, especially when they affect production systems, executive devices, or high-value assets.

Key Capabilities of EDR

EDR combines several capabilities that help security teams move from detection to action.

Capability	What It Does
Endpoint telemetry	Collects process, file, registry, network, user, and system activity from endpoints
Behavioral detection	Identifies suspicious activity based on behavior, not only known signatures
Process lineage	Shows how a process started, which parent process created it, and what actions followed
Command-line visibility	Helps analysts understand how scripts, shells, and administrative tools were used.
Threat hunting	Enables analysts to search across endpoints for indicators, behaviors, and attack-related activity patterns
Investigation timeline	Organizes events so analysts can reconstruct the attack sequence
Response actions	Supports containment and remediation, such as network isolation, process termination, quarantine, rollback, and artifact collection
Threat intelligence	Adds context about known indicators of compromise, malware families, attacker infrastructure, and tactics

These capabilities are most useful when they work together. Telemetry provides evidence. Detection logic identifies suspicious behavior. Investigation tools explain the sequence. Response actions help contain the threat.

EDR vs. Antivirus

EDR and antivirus are related, but they solve different problems.

Antivirus focuses mainly on prevention. It detects and blocks known malware using signatures, reputation, heuristics, and other prevention techniques. This is still important because many endpoint attacks involve malicious files at some stage.

EDR focuses on detection, investigation, and response. It monitors endpoint behavior and helps analysts understand what happened after suspicious activity appears.

The difference becomes clear during an attack. Antivirus may block a known malware file. EDR may detect the activity around it, such as a phishing document launching a script, a command shell downloading a payload, a credential dumping attempt, or lateral movement from one endpoint to another.

EDR does not replace antivirus. In most environments, antivirus and EDR work together. Antivirus reduces known threats. EDR gives analysts the visibility and response tools needed when threats bypass prevention or behave in unexpected ways.

EDR vs. EPP vs. XDR

EDR is often discussed with EPP and XDR. The terms are related, but each one has a different role.

Endpoint Protection Platform, or EPP, focuses on prevention and endpoint protection management. It may include anti-malware, device control, host firewall policy, patch visibility, and security assessment.

EDR focuses on endpoint detection, investigation, and response. It helps analysts identify suspicious behavior, reconstruct attack paths, and contain affected endpoints.

Extended Detection and Response, or XDR, expands detection and response beyond endpoints. XDR connects endpoint data with signals from identity, email, network, cloud, and SaaS environments.

The relationship is straightforward. EPP helps reduce endpoint risk before an incident. EDR helps investigate and respond to endpoint-based threats. XDR helps connect endpoint activity with signals from other security layers.

Common EDR Use Cases

Ransomware Detection and Containment

Ransomware often creates visible endpoint behavior before damage spreads. EDR can detect suspicious encryption patterns, abnormal file modifications, malicious process behavior, and attempts to disable security tools.

When ransomware activity appears, EDR can help isolate the affected endpoint, stop malicious processes, and support investigation into the initial access path.

Phishing-Based Endpoint Attacks

Phishing may lead to malicious document execution, script activity, suspicious downloads, or credential theft. EDR helps analysts see what happened after the user opened the file or clicked the link.

This matters because the email event alone may not show whether the endpoint was actually compromised.

Credential Theft

Attackers often try to collect passwords, cached credentials, browser cookies, tokens, or other authentication material from endpoints. EDR can detect suspicious access to credential stores, abnormal administrative tools, and post-compromise behavior.

Once credentials are stolen, the attacker may look like a valid user. EDR helps connect that activity back to the endpoint where the compromise began.

Living-off-the-Land Activity

Living-off-the-land attacks use legitimate tools such as PowerShell, Windows Management Instrumentation, remote desktop utilities, or command-line tools for malicious purposes.

These techniques can avoid basic file-based detection because the tools are trusted. EDR helps detect unusual usage patterns, suspicious command-line activity, and abnormal process relationships.

Lateral Movement

After compromising one endpoint, attackers may try to move to other systems. EDR can help detect remote execution, abnormal authentication patterns, suspicious administrator activity, and connections to sensitive systems.

Stopping lateral movement early can limit the scope of an incident.

For a real-world example of how endpoint visibility supports investigation and response, see Securing Visibility is Key: Company R's EDR Success Story.

Case Study

Securing Visibility is Key: Company R's EDR Success Story

How to Strengthen EDR Operations

EDR is most effective when security teams treat it as an operational workflow, not only a deployed tool.

First, endpoint coverage needs to be consistent. Security teams should confirm that laptops, desktops, servers, and workloads have the right agent installed and reporting correctly. Unmanaged endpoints create blind spots.

Second, detection rules need tuning. Too many low-quality alerts can slow analysts down. EDR should help the team focus on high-risk behavior, such as credential access, suspicious script execution, privilege escalation, ransomware activity, and lateral movement.

Third, response actions should be defined before an incident. Teams need to know when to isolate a device, when to kill a process, when to collect forensic data, and when to escalate to incident response.

EDR data should also be connected with other security signals. Endpoint activity becomes more useful when analysts can correlate it with identity events, email activity, network connections, and cloud access.

Whitepaper

"Response Beyond Detection" Security Strategy Leveraging EDR

FAQ

What We Do for EDR

AhnLab helps security teams detect, investigate, and respond to endpoint threats with endpoint-level visibility and context.

AhnLab EDR analyzes endpoint behavior, maps activity to the MITRE ATT&CK framework, and supports response actions such as network quarantine, process termination, rollback, and artifact collection. For teams that need expert-led security operations, AhnLab MDR provides managed detection, threat analysis, hunting, and response guidance.

EDR can also work as part of a broader endpoint security program. AhnLab EPP supports integrated endpoint protection management, helping teams connect prevention, policy enforcement, and detection in one endpoint security workflow.