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Device discovery overview

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Applies to:

Protecting your environment requires taking inventory of the devices that are in your network. However, mapping devices in a network can often be expensive, challenging, and time-consuming.

Microsoft Defender for Endpoint provides a device discovery capability that helps you find unmanaged devices connected to your corporate network without the need for extra appliances or cumbersome process changes. Device discovery uses onboarded endpoints, in your network to collect, probe, or scan your network to discover unmanaged devices. The device discovery capability allows you to discover:

  • Enterprise endpoints (workstations, servers, and mobile devices) that aren't yet onboarded to Defender for Endpoint
  • Network devices like routers and switches
  • IoT devices like printers and cameras

Unknown and unmanaged devices introduce significant risks to your network - whether it's an unpatched printer, network devices with weak security configurations, or a server with no security controls. Once devices are discovered, you can:

  • Onboard unmanaged endpoints to the service, increasing the security visibility on them.
  • Reduce the attack surface by identifying and assessing vulnerabilities, and detecting configuration gaps.

Watch this video for a quick overview of how to assess and onboard unmanaged devices that Defender for Endpoint discovered.

With this capability, a security recommendation to onboard devices to Defender for Endpoint is available as part of the existing Microsoft Defender Vulnerability Management experience.

Discovery methods

You can choose the discovery mode to be used by your onboarded devices. The mode controls the level of visibility you can get for unmanaged devices in your corporate network.

There are two modes of discovery available:

  • Basic discovery: In this mode, endpoints passively collect events in your network and extract device information from them. Basic discovery uses the SenseNDR.exe binary for passive network data collection and no network traffic is initiated. Endpoints extract data from all network traffic seen by an onboarded device. With basic discovery, you only gain limited visibility of unmanaged endpoints in your network.

  • Standard discovery (recommended): This mode allows endpoints to actively find devices in your network to enrich collected data and discover more devices - helping you build a reliable and coherent device inventory. In addition to devices that were observed using the passive method, standard mode also uses common discovery protocols that use multicast queries in the network to find even more devices. Standard mode uses smart, active probing to discover additional information about observed devices to enrich existing device information. When Standard mode is enabled, minimal and negligible network activity generated by the discovery sensor might be observed by network monitoring tools in your organization.

You can change and customize your discovery settings, for more information, see Configure device discovery.

Important

Standard discovery is the default mode for all customers starting July 19, 2021. You can choose to change this configuration to basic through the settings page. If you choose basic mode, you'll only gain limited visibility of unmanaged endpoints in your network.

The discovery engine distinguishes between network events that are received in the corporate network versus outside of the corporate network. Devices that aren't connected to corporate networks won't be discovered or listed in the device inventory.

Device inventory

Devices that were discovered but aren't onboarded to and secured by Defender for Endpoint are listed in the device inventory.

To assess these devices, you can use a filter in the device inventory list called Onboarding status, which can have any of the following values:

  • Onboarded: The endpoint is onboarded to Defender for Endpoint.
  • Can be onboarded: The endpoint was discovered in the network and the Operating System was identified as one that is supported by Defender for Endpoint, but it isn't currently onboarded. We highly recommend onboarding these devices.
  • Unsupported: The endpoint was discovered in the network but isn't supported by Defender for Endpoint.
  • Insufficient info: The system couldn't determine the supportability of the device. Enabling standard discovery on more devices in the network can enrich the discovered attributes.

The device inventory dashboard

Tip

You can always apply filters to exclude unmanaged devices from the device inventory list. You can also use the onboarding status column on API queries to filter out unmanaged devices.

For more information, see Device inventory.

Network device discovery

The large number of unmanaged network devices deployed in an organization creates a large surface area of attack, and represents a significant risk to the entire enterprise. Defender for Endpoint network discovery capabilities helps you ensure network devices are discovered, accurately classified, and added to the asset inventory.

Network devices aren't managed as standard endpoints, as Defender for Endpoint doesn't have a sensor built into the network devices themselves. These types of devices require an agentless approach where a remote scan obtains the necessary information from the devices. To do this, a designated Defender for Endpoint device is used on each network segment to perform periodic authenticated scans of preconfigured network devices. Defender for Endpoint's vulnerability management capabilities provide integrated workflows to secure discovered switches, routers, WLAN controllers, firewalls, and VPN gateways.

For more information, see Network devices.

Device discovery integration

To address the challenge of gaining enough visibility to locate, identify, and secure your complete OT/IOT asset inventory Defender for Endpoint now supports the following integration:

  • Microsoft Defender for IoT: This integration combines Defender for Endpoint's device discovery capabilities with Microsoft Defender for IoT in the Microsoft Defender portal (Preview) to secure:

Vulnerability assessment on discovered devices

Vulnerabilities and risks on your devices as well as other discovered unmanaged devices in the network are part of the current Defender Vulnerability Management flows under "Security Recommendations" and represented in entity pages across the portal. Search for "SSH" related security recommendations to find SSH vulnerabilities that are related for unmanaged and managed devices.

The security recommendations dashboard

Use advanced hunting on discovered devices

You can use advanced hunting queries to gain visibility on discovered devices. Find details about discovered devices in the DeviceInfo table, or network-related information about those devices, in the DeviceNetworkInfo table.

The Advanced hunting page on which queries can be used

Query discovered devices details

Run this query on the DeviceInfo table to return all discovered devices along with the most up-to-date details for each device:

DeviceInfo
| summarize arg_max(Timestamp, *) by DeviceId  // Get latest known good per device Id
| where isempty(MergedToDeviceId) // Remove invalidated/merged devices
| where OnboardingStatus != "Onboarded"

By invoking the SeenBy function, in your advanced hunting query, you can get detail on which onboarded device a discovered device was seen by. This information can help determine the network location of each discovered device and subsequently, help to identify it in the network.

DeviceInfo
| where OnboardingStatus != "Onboarded"
| summarize arg_max(Timestamp, *) by DeviceId 
| where isempty(MergedToDeviceId) 
| limit 100
| invoke SeenBy()
| project DeviceId, DeviceName, DeviceType, SeenBy

For more information, see the SeenBy() function.

Device discovery leverages Defender for Endpoint onboarded devices as a network data source to attribute activities to non-onboarded devices. The network sensor on the Defender for Endpoint onboarded device identifies two new connection types:

  • ConnectionAttempt - An attempt to establish a TCP connection (syn)
  • ConnectionAcknowledged - An acknowledgment that a TCP connection was accepted (syn\ack)

This means that when a non-onboarded device attempts to communicate with an onboarded Defender for Endpoint device, the attempt generates a DeviceNetworkEvent and the non-onboarded device activities can be seen on the onboarded device timeline, and through the Advanced hunting DeviceNetworkEvents table.

You can try this example query:

DeviceNetworkEvents
| where ActionType == "ConnectionAcknowledged" or ActionType == "ConnectionAttempt"
| take 10

Next steps

Tip

Do you want to learn more? Engage with the Microsoft Security community in our Tech Community: Microsoft Defender for Endpoint Tech Community.