Query the enterprise exposure graph

Article
11/04/2024

Use the enterprise exposure graph in Microsoft Security Exposure Management to proactively hunt for enterprise exposure threats in advanced hunting in the Microsoft Defender portal.

This article provides some examples, tips, and hints for constructing queries in the enterprise exposure graph.

Prerequisites

Read about attack surface management.
Review required permissions for working with the graph.

Build advanced hunting queries

Review best practices for building advanced hunting queries
Get started with Kusto Query Language (KQL)

Use the make-graph operator

Kusto's make-graph operator loads nodes and edges data into memory.

Since Kusto only loads the columns that are in use, there's no need to explicitly select columns.
However, the NodeProperties column contains all node information and so is large.
In most scenarios, it's useful to extract only the information required before feeding it into the make-graph operator.

Example

let FilteredNodes = ExposureGraphNodes
| extend ContainsSensetiveData = NodeProperties has "containsSensitiveData"
| project Id, ContainsSensetiveData, Label, EntityIds, Categories;
Edges
| make-graph SourceNodeId --> TargetNodeId with FilteredNodes on Id
..

Use dynamic columns and smart-indexing

NodeProperties and Categories are dynamic columns.

Kusto knows those columns contain json-like content, and applies smart indexing.
However, not all Kusto operators use the index. For example, set_has_element, isempty, isnotnull don't use the index when they're applied to a dynamic column and isnotnull(Properties["containsSensitiveData"] doesn't use the index.
Instead, use the has() operator, which always uses the index.

Example

In the following query the has operator checks for the data string, and set_has_element checks for the data element.

Using both operators is important as the has() operator returns true even for a category prefix_data.

Categories has('data') and set_has_element(Categories, 'data')

Learn more about understanding string terms.

Example exposure queries

The following examples can help you write queries to understand the security exposure data in your tenant.

List all node labels in your tenant

The following query groups the data in the ExposureGraphNodes table and uses Kusto's summarize operator to list it by NodeLabel.

ExposureGraphNodes
| summarize by NodeLabel

List all edge labels in your tenant

The following query groups the data in the ExposureGraphEdges table and uses Kusto's summarize operator to list it by edge labels (EdgeLabel).

ExposureGraphEdges
| summarize by EdgeLabel

List all connections from a specified node label

The following query groups the data in the ExposureGraphEdges table, and where the source node label is microsoft.compute/virtualmachines, it summarizes the virtual machine's by EdgeLabel. It summarizes the edges that connect assets to virtual machines in your security exposure graph.

ExposureGraphEdges
| where SourceNodeLabel == "microsoft.compute/virtualmachines"
| summarize by EdgeLabel

List all connections to a specific node label

The following query summarizes edges that connect virtual machines to other security exposure graph assets. It groups the data in the ExposureGraphEdges table, and where the target node label is microsoft.compute/virtualmachines, it uses Kusto's summarize operator to list the target node label by EdgeLabel.

ExposureGraphEdges
| where TargetNodeLabel == "microsoft.compute/virtualmachines"
| summarize by EdgeLabel

List properties of a specific node label

The following query lists properties of the virtual machine node label. It groups the data in the ExposureGraphNodes table, filtered to show the node label "microsoft.compute/virtualmachines" results only. With the project-keep operator, the query keeps the NodeProperties column. The data returned is limited to one row.

ExposureGraphNodes
| where NodeLabel == "microsoft.compute/virtualmachines"
| project-keep NodeProperties
| take 1

Query the exposure graph

To query the exposure graph:

In the Microsoft Defender portal, select hunting -> advanced hunting.
In the Query area, type your query. Use the graph schema, functions, and operator tables or the following examples to help you build your query.
Select run query.

Graph-oriented query examples

Use these graph-oriented query examples to help you write better security exposure queries. The examples search for patterns to expose relationships between entities that can uncover risk. They show you how to correlate context with incident/alert signals.

List all node labels with an edge to a specific node label

The following query results in a list of all incoming node labels with a connector to the virtual machine node label. It builds a graph structure by mapping the SourceNodeId column data in the ExposureGraphEdges table to the TargetNodeId column in the ExposureGraphNodes table with the make-graph operator to build a graph structure.

It then uses the graph-match operator to make a graph pattern where the target node TargetNode and NodeLabel match microsoft.compute/virtualmachines. The project operator is used to keep only the IncomingNodeLabels. It lists the results by IncomingNodeLabels.

ExposureGraphEdges
| make-graph SourceNodeId --> TargetNodeId with ExposureGraphNodes
on NodeId
| graph-match (SourceNode)-[edges]->(TargetNode)
       where TargetNode.NodeLabel == "microsoft.compute/virtualmachines"
       project IncomingNodeLabels = SourceNode.NodeLabel 
| summarize by IncomingNodeLabels

List all node labels edging a specific node label

The following query results in a list of all the outgoing node labels with a connector to the virtual machine node label.

It builds a graph structure by mapping the SourceNodeId column uses the data in the ExposureGraphEdges table to the TargetNodeId column in the ExposureGraphNodes table using the make-graph operator to build a graph structure.
It then uses the graph-match operator to match the graph pattern where SourceNode and NodeLabel match microsoft.compute/virtualmachines.
The project operator is used to keep only the OutgoingNodeLabels. It lists the results by OutgoingNodeLabels.

ExposureGraphEdges
| make-graph SourceNodeId --> TargetNodeId with ExposureGraphNodes
on NodeId
| graph-match (SourceNode)-[edges]->(TargetNode)
       where SourceNode.NodeLabel == "microsoft.compute/virtualmachines"
       project OutgoingNodeLabels = SourceNode.NodeLabel 
| summarize by OutgoingNodeLabels

Discover VMs exposed to the internet with an RCE vulnerability

The following query allows you to discover virtual machines exposed to the internet and to a Remote Code Execution (RCE) vulnerability.

It uses the ExposureGraphNodes schema table.
When both NodeProperties exposedToInternet and vulnerableToRCE are true, it checks that the category (Categories) is virtual machines (virtual_machine).

ExposureGraphNodes
| where isnotnull(NodeProperties.rawData.exposedToInternet)
| where isnotnull(NodeProperties.rawData.vulnerableToRCE)
| where Categories has "virtual_machine" and set_has_element(Categories, "virtual_machine")

Discover internet facing devices with a privilege escalation vulnerability

The following query looks for internet facing devices exposed to a privilege escalation vulnerability, which could allow access to higher level privileges within the system.

It uses the ExposureGraphNodes schema table.
When NodeProperties is both internet facing (IsInternetFacing) and VulnerableToPrivilegeEscalation, the query checks that the items in Categories are actually devices (device).

ExposureGraphNodes
| where isnotnull(NodeProperties.rawData.IsInternetFacing)
| where isnotnull(NodeProperties.rawData.VulnerableToPrivilegeEscalation)
| where set_has_element(Categories, "device")

Show all users logged in to more than one critical device

This query results in a list of users logged into more than one critical device, along with the number of devices they're logged into.

It creates an IdentitiesAndCriticalDevices table using ExposureGraphNodes data filtered either by devices with a criticality level above 4 or by identity.
It then makes a graph structure with the make-graph operator, where the EdgeLabel is Can Authenticate As.
It uses the graph-match operator to match instances where a device matches an identity.
Then it uses the project operator to keep identity IDs and device IDs.
The mv-apply operator filters device IDs and identity IDs by type. It summarizes them and displays the results in a table with the headers, Number Of devices user is logged-in to, and User Id.

let IdentitiesAndCriticalDevices = ExposureGraphNodes
| where
 // Critical Device
 (set_has_element(Categories, "device") and isnotnull(NodeProperties.rawData.criticalityLevel) and NodeProperties.rawData.criticalityLevel.criticalityLevel < 4)
 // or identity
 or set_has_element(Categories, "identity");
ExposureGraphEdges
| where EdgeLabel == "Can Authenticate As"
| make-graph SourceNodeId --> TargetNodeId with IdentitiesAndCriticalDevices on NodeId
| graph-match (Device)-[canConnectAs]->(Identity)
       where set_has_element(Identity.Categories, "identity") and set_has_element(Device.Categories, "device")
       project IdentityIds=Identity.EntityIds, DeviceIds=Device.EntityIds
| mv-apply DeviceIds on (
    where DeviceIds.type == "DeviceInventoryId")
| mv-apply IdentityIds on (
    where IdentityIds.type == "SecurityIdentifier")
| summarize NumberOfDevicesUserLoggedinTo=count() by tostring(IdentityIds.id)
| where NumberOfDevicesUserLoggedinTo > 1
| project ["Number Of devices user is logged-in to"]=NumberOfDevicesUserLoggedinTo, ["User Id"]=IdentityIds_id

Show client devices with a critical vulnerability/users that have access to high value servers

The following query results in a list of devices with RCE vulnerabilities and their device IDs, and devices with high critical vulnerabilities and their device IDs.

It creates an IdentitiesAndCriticalDevices table that includes devices (device) with RCE vulnerabilities with criticality lower than four, and identities (identity) that with through filtering and pattern matching, show devices with critical vulnerabilities.
The list is filtered to show only those connections that have edge labels Can Authenticate As and CanRemoteInteractiveLogonTo.

let IdentitiesAndCriticalDevices = ExposureGraphNodes // Reduce the number of nodes to match
| where 
 // Critical devices & devices with RCE vulnerabilities
 (set_has_element(Categories, "device") and 
    (
        // Critical devices
        (isnotnull(NodeProperties.rawData.criticalityLevel) and NodeProperties.rawData.criticalityLevel.criticalityLevel < 4)
        or 
        // Devices with RCE vulnerability
        isnotnull(NodeProperties.rawData.vulnerableToRCE)
    )
  )
 or 
 // identity
 set_has_element(Categories, "identity");
ExposureGraphEdges
| where EdgeLabel in~ ("Can Authenticate As", "CanRemoteInteractiveLogonTo") // Reduce the number of edges to match
| make-graph SourceNodeId --> TargetNodeId with IdentitiesAndCriticalDevices on NodeId
| graph-match (DeviceWithRCE)-[CanConnectAs]->(Identity)-[CanRemoteLogin]->(CriticalDevice)
       where 
             CanConnectAs.EdgeLabel =~ "Can Authenticate As" and
             CanRemoteLogin.EdgeLabel =~ "CanRemoteInteractiveLogonTo" and
             set_has_element(Identity.Categories, "identity") and 
             set_has_element(DeviceWithRCE.Categories, "device") and isnotnull(DeviceWithRCE.NodeProperties.rawData.vulnerableToRCE) and
             set_has_element(CriticalDevice.Categories, "device") and isnotnull(CriticalDevice.NodeProperties.rawData.criticalityLevel)
       project DeviceWithRCEIds=DeviceWithRCE.EntityIds, DeviceWithRCEName=DeviceWithRCE.NodeName, CriticalDeviceIds=CriticalDevice.EntityIds, CriticalDeviceName=CriticalDevice.NodeName

Provide all paths from specific node ID to a node with a specific label

This query displays the path from a specific IP node, passing through up to three assets that results in a connection to the virtual machine node label.

It uses the ExposureGraphNodes and ExposureGraphEdges schema tables and the make-graph and graph-match operators to create a graph structure.
With the project operator, it displays a list of IP IDs, IP properties, virtual machine IDs, and virtual machine properties.

let IPsAndVMs = ExposureGraphNodes
| where (set_has_element(Categories, "ip_address") or set_has_element(Categories, "virtual_machine"));
ExposureGraphEdges
| make-graph SourceNodeId --> TargetNodeId with IPsAndVMs on NodeId
| graph-match (IP)-[anyEdge*1..3]->(VM)
       where set_has_element(IP.Categories, "ip_address") and set_has_element(VM.Categories, "virtual_machine")
       project IpIds=IP.EntityIds, IpProperties=IP.NodeProperties.rawData, VmIds=VM.EntityIds, VmProperties=VM.NodeProperties.rawData

Next steps

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Query the enterprise exposure graph

Prerequisites

Build advanced hunting queries

Use the make-graph operator

Example

Use dynamic columns and smart-indexing

Example

Example exposure queries

List all node labels in your tenant

List all edge labels in your tenant

List all connections from a specified node label

List all connections to a specific node label

List properties of a specific node label

Query the exposure graph

Graph-oriented query examples

List all node labels with an edge to a specific node label

List all node labels edging a specific node label

Discover VMs exposed to the internet with an RCE vulnerability

Discover internet facing devices with a privilege escalation vulnerability

Show all users logged in to more than one critical device

Show client devices with a critical vulnerability/users that have access to high value servers

Provide all paths from specific node ID to a node with a specific label

Next steps

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