What is Network Detection and Response (NDR), and how does it work?

Network Detection and Response (NDR) gives you clear visibility into what is happening across your network. It continuously monitors network traffic and flags suspicious or malicious activity, including threats that can slip past endpoints or perimeter controls. NDR passively inspects traffic using five detection engines (with some analytics running on a schedule for deeper correlation) and sends actionable detections into Sophos Fusion so your team can investigate and respond quickly.

Why is NDR important for visibility into east-west and north-south traffic?

NDR reveals what is happening inside your network (east-west traffic) as well as traffic entering or leaving it (north-south traffic). This level of visibility helps you detect suspicious activity between devices, command-and-control (C2) behavior, and unusual data movement. It strengthens your defenses across the entire attack surface, not only at the perimeter.

How is NDR different from EDR, XDR, SIEM, and firewalls?

Each tool plays a different role: EDR monitors activity on endpoints. NDR analyzes network traffic to expose suspicious activity between devices, including unmanaged, internet-of-things (IoT), and rogue devices. SIEM collects and correlates log data. Firewalls manage and control traffic entering and leaving the network. Sophos NDR complements these tools by adding AI-powered network analytics and delivering high-value detections directly into Sophos Fusion to support extended detection and response (XDR) and managed detection and response (MDR) workflows.

What threats can NDR detect that other tools often miss?

Some threats hide in network behavior rather than leaving clear traces on endpoints. NDR helps uncover activity such as lateral movement, malware command-and-control (including zero-day C2 patterns), rogue or unmanaged devices, insider-driven data movement, and suspicious encrypted traffic behavior. By focusing on network activity, NDR brings these blind spots into view.

How does NDR use AI and behavioral analytics to reduce false positives?

NDR blends deep learning, behavioral analytics, and rule-based logic across multiple detection engines. It correlates evidence and applies clustering and scoring before generating detections. This approach cuts down on noise, improves accuracy, and helps identify unknown or encrypted threats without overwhelming the team.

What data does NDR analyze, and what is required to deploy it?

NDR analyzes network flows created from packet data and enriches them with protocol details, traffic behavior, TLS attributes, and other risk indicators. Deployment is simple: A passive sensor connects to a SPAN or mirror port, providing broad visibility without adding latency, disrupting operations, or introducing an inline point of failure.

How do you deploy NDR in hybrid or multi-cloud environments?

NDR is flexible. You can deploy it as a virtual appliance on VMware or Hyper-V, run it in AWS, or use certified hardware. Sensors monitor important network segments, and detections flow into Sophos Fusion for a unified view across on-premises and cloud environments.

How does NDR integrate with XDR, MDR, and firewall response workflows?

NDR detections feed into Sophos Fusion, the industry’s most complete AI-Native Cybersecurity Defense System, where analysts can investigate, correlate telemetry, and act. Integrated workflows can also push threat intelligence to other Sophos products. For example, analysts can push a threat feed to Sophos Firewall to trigger Active Threat Response, automatically isolating a compromised host and blocking related malicious communications to contain threats faster.

What should you look for when evaluating an NDR solution?

A strong NDR solution should offer multiple detection techniques, AI-based encrypted traffic analysis, high-value detections supported by scoring, flexible deployment choices, and smooth integration with XDR or MDR programs. The right solution should close visibility gaps and improve response times without adding operational complexity.

What does NDR cost, and how do you justify ROI?

Sophos NDR is licensed based on users and servers, with the virtual appliance included in the subscription. Organizations justify ROI by closing visibility gaps, reducing dwell time, improving analyst efficiency with high-value detections, and speeding containment through automated response workflows, helping prevent costly incidents while increasing the impact of existing security investments.

Sophos Network Detection and Response

Sophos NDR Provides Critical Visibility into Network Activity That Other Products Miss

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Detect Suspicious Behaviors That Extend Beyond Your Firewalls and Endpoints

Sophos NDR works together with your managed endpoints and firewalls to monitor network activity for suspicious and malicious patterns they cannot see. It detects abnormal traffic flows from unmanaged systems and IoT devices, rogue assets, insider threats, previously unseen zero-day attacks, and unusual patterns deep within the network.

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Sophos NDR detects a range of network behaviors, making it an effective solution for identifying:

Unprotected Devices

Identify legitimate devices that aren't protected and could be used as entry points, including IoT and OT assets.

Rogue Assets

Pinpoint unauthorized and potentially malicious devices communicating across a network.

Insider Threats

Gain visibility to network traffic flows and “normal” data movement from inside an organization.

Zero-Day Attacks

Detect server command-and-control (C2) attempts based on patterns found in session packets.

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Early Detection and Automatic Response

Sophos cross-product automation between NDR, XDR, MDR, and Firewall provides immediate response to stop active threats dead in their tracks.

sophos-ndr-active-threat-response-diagram

How it works: Sophos NDR monitors traffic deep within the network, sending suspicious activity to Sophos Fusion’s context lake for further analysis. In the event an active threat or adversary is identified, analysts can immediately push a threat feed to Sophos Firewall that can coordinate an Active Threat Response to isolate and block malicious activity automatically in real-time.

Learn More About Sophos MDR

Introducing the Sophos AI-Native Cybersecurity Defense System.

Sophos Fusion

Sophos NDR is part of Sophos Fusion, the industry's most complete cyber defense system, engineered for a world where threats move at AI speed.

Sophos NDR provides AI threat detection of malicious traffic patterns and feeds that information into Sophos Fusion to enable a coordinated response to active threats.

Learn more about Sophos Fusion

5 Independent Detection Engines That Work in Real-Time

Data Detection Engine

Extensible query engine uses a deep learning prediction model to analyze encrypted traffic for patterns across unrelated network flows and detect port scanning and SSH brute force activity.

Domain Generation Algorithm

Identifies dynamic domain generation technology used by malware to avoid detection.

Deep Packet Inspection

Uses known indicators of compromise to identify threat actors and malicious tactics, techniques, and procedures across encrypted and unencrypted network traffic.

Session Risk Analytics

Powerful logic engine utilizes rules that send alerts based on session-based risk factors.

Encrypted Payload Analysis

Detects zero-day C2 servers and new variants of malware families based on patterns found in the session size, direction, and interarrival times.

Get valuable insights and perform deep investigations

Sophos Fusion and the Sophos NDR Investigation Console provides all the tools you need to easily:

Get instant insights into into network and application activity, risky flows, and suspicious traffic detections in Sophos Fusion
Drill-down and perform deep forensic investigations with the Investigation Console
Identify all unmanaged, IoT, and potential rogue assets on your network including their manufacturer and operating system

Frequently asked questions

Network Detection and Response (NDR) gives you clear visibility into what is happening across your network. It continuously monitors network traffic and flags suspicious or malicious activity, including threats that can slip past endpoints or perimeter controls. NDR passively inspects traffic using five detection engines (with some analytics running on a schedule for deeper correlation) and sends actionable detections into Sophos Fusion so your team can investigate and respond quickly.
NDR reveals what is happening inside your network (east-west traffic) as well as traffic entering or leaving it (north-south traffic). This level of visibility helps you detect suspicious activity between devices, command-and-control (C2) behavior, and unusual data movement. It strengthens your defenses across the entire attack surface, not only at the perimeter.
Each tool plays a different role:
- EDR monitors activity on endpoints.
- NDR analyzes network traffic to expose suspicious activity between devices, including unmanaged, internet-of-things (IoT), and rogue devices.
- SIEM collects and correlates log data.
- Firewalls manage and control traffic entering and leaving the network.
Sophos NDR complements these tools by adding AI-powered network analytics and delivering high-value detections directly into Sophos Fusion to support extended detection and response (XDR) and managed detection and response (MDR) workflows.
Some threats hide in network behavior rather than leaving clear traces on endpoints. NDR helps uncover activity such as lateral movement, malware command-and-control (including zero-day C2 patterns), rogue or unmanaged devices, insider-driven data movement, and suspicious encrypted traffic behavior. By focusing on network activity, NDR brings these blind spots into view.
NDR blends deep learning, behavioral analytics, and rule-based logic across multiple detection engines. It correlates evidence and applies clustering and scoring before generating detections. This approach cuts down on noise, improves accuracy, and helps identify unknown or encrypted threats without overwhelming the team.
NDR analyzes network flows created from packet data and enriches them with protocol details, traffic behavior, TLS attributes, and other risk indicators. Deployment is simple: A passive sensor connects to a SPAN or mirror port, providing broad visibility without adding latency, disrupting operations, or introducing an inline point of failure.
NDR is flexible. You can deploy it as a virtual appliance on VMware or Hyper-V, run it in AWS, or use certified hardware. Sensors monitor important network segments, and detections flow into Sophos Fusion for a unified view across on-premises and cloud environments.
NDR detections feed into Sophos Fusion, the industry’s most complete AI-Native Cybersecurity Defense System, where analysts can investigate, correlate telemetry, and act. Integrated workflows can also push threat intelligence to other Sophos products. For example, analysts can push a threat feed to Sophos Firewall to trigger Active Threat Response, automatically isolating a compromised host and blocking related malicious communications to contain threats faster.
A strong NDR solution should offer multiple detection techniques, AI-based encrypted traffic analysis, high-value detections supported by scoring, flexible deployment choices, and smooth integration with XDR or MDR programs. The right solution should close visibility gaps and improve response times without adding operational complexity.
Sophos NDR is licensed based on users and servers, with the virtual appliance included in the subscription. Organizations justify ROI by closing visibility gaps, reducing dwell time, improving analyst efficiency with high-value detections, and speeding containment through automated response workflows, helping prevent costly incidents while increasing the impact of existing security investments.