Detection rules › Kusto

TI Map IP Entity to VMConnection

Severity
medium
Time window
14d
Group by
Id, ObservableValue, RemoteIp, TI_ipEntity
Source
github.com/Azure/Azure-Sentinel

This query maps any IP indicators of compromise (IOCs) from threat intelligence (TI), by searching for matches in VMConnection.

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1071 Application Layer Protocol

Rule body kusto

id: aed70d71-adb2-4f73-becd-02150b13950b
name: TI Map IP Entity to VMConnection
description: |
  This query maps any IP indicators of compromise (IOCs) from threat intelligence (TI), by searching for matches in VMConnection.
severity: Medium
requiredDataConnectors:
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: AzureMonitor(VMInsights)
    dataTypes:
      - VMConnection
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
query: |
  let dt_lookBack = 1h; // Look back 1 hour for VMConnection events
  let ioc_lookBack = 14d; // Look back 14 days for threat intelligence indicators
  // Fetch threat intelligence indicators related to IP addresses
  let IP_Indicators = ThreatIntelIndicators
  //extract key part of kv pair
       | extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
       | where IndicatorType in ("ipv4-addr", "ipv6-addr", "network-traffic")
       | extend NetworkSourceIP = toupper(ObservableValue)
       | extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
    | where TimeGenerated >= ago(ioc_lookBack)
    | extend TI_ipEntity = iff(isnotempty(NetworkSourceIP), NetworkSourceIP, NetworkSourceIP)
    | extend TI_ipEntity = iff(isempty(TI_ipEntity) and isnotempty(NetworkSourceIP), NetworkSourceIP, TI_ipEntity)
    | extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
    | where ipv4_is_private(TI_ipEntity) == false and  TI_ipEntity !startswith "fe80" and TI_ipEntity !startswith "::" and TI_ipEntity !startswith "127."
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
    | where IsActive and (ValidUntil > now() or isempty(ValidUntil));
  // Perform a join between IP indicators and VMConnection events
  IP_Indicators
     | project-reorder *, Tags, TrafficLightProtocolLevel, NetworkSourceIP, Type, TI_ipEntity
    // Use innerunique to keep performance fast and result set low, as we only need one match to indicate potential malicious activity that needs investigation
    | join kind=innerunique (
        VMConnection
        | where TimeGenerated >= ago(dt_lookBack)
        | extend VMConnection_TimeGenerated = TimeGenerated
    )
    on $left.TI_ipEntity == $right.RemoteIp
    // Filter out VMConnection events that occurred after the expiration of the corresponding indicator
    | where VMConnection_TimeGenerated < ValidUntil
    // Group the results by IndicatorId and keep the VMConnection event with the latest timestamp
    | summarize VMConnection_TimeGenerated = arg_max(VMConnection_TimeGenerated, *) by Id, RemoteIp
    // Select the desired output fields
    | extend Description = tostring(parse_json(Data).description)
    | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
    | project VMConnection_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence,
      TI_ipEntity, Computer, Direction, ProcessName, SourceIp, DestinationIp, RemoteIp, Protocol, DestinationPort, NetworkSourceIP, Type, Url
    | extend timestamp = VMConnection_TimeGenerated, HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))
entityMappings:
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: HostName
      - identifier: DnsDomain
        columnName: DnsDomain
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: RemoteIp
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.4.6
kind: Scheduled

Stages and Predicates

Parameters

let dt_lookBack = 1h;
let ioc_lookBack = 14d;

The stages below define let IP_Indicators (the rule's main pipeline source).

Stage 1: source

ThreatIntelIndicators

Stage 2: extend

| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))

Stage 3: where

| where IndicatorType in ("ipv4-addr", "ipv6-addr", "network-traffic")

Stage 4: extend

| extend NetworkSourceIP = toupper(ObservableValue)

Stage 5: extend

| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)

Stage 6: where

| where TimeGenerated >= ago(ioc_lookBack)

Stage 7: extend (3 consecutive steps)

| extend TI_ipEntity = iff(isnotempty(NetworkSourceIP), NetworkSourceIP, NetworkSourceIP)
| extend TI_ipEntity = iff(isempty(TI_ipEntity) and isnotempty(NetworkSourceIP), NetworkSourceIP, TI_ipEntity)
| extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
TI_ipEntity =
ifisnotempty(NetworkSourceIP)NetworkSourceIP
elseNetworkSourceIP

Stage 8: where

| where ipv4_is_private(TI_ipEntity) == false and  TI_ipEntity !startswith "fe80" and TI_ipEntity !startswith "::" and TI_ipEntity !startswith "127."

Stage 9: summarize

| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue

Stage 10: where

| where IsActive and (ValidUntil > now() or isempty(ValidUntil))

The stages below run on IP_Indicators (the outer pipeline).

Stage 11: project-reorder

IP_Indicators
| project-reorder *, Tags, TrafficLightProtocolLevel, NetworkSourceIP, Type, TI_ipEntity

Stage 12: join

| join kind=innerunique (
      VMConnection
      | where TimeGenerated >= ago(dt_lookBack)
      | extend VMConnection_TimeGenerated = TimeGenerated
  )
  on $left.TI_ipEntity == $right.RemoteIp

Stage 13: where

| where VMConnection_TimeGenerated < ValidUntil

Stage 14: summarize

| summarize VMConnection_TimeGenerated = arg_max(VMConnection_TimeGenerated, *) by Id, RemoteIp

Stage 15: extend

| extend Description = tostring(parse_json(Data).description)

Stage 16: extend

| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))

Stage 17: project

| project VMConnection_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence,
    TI_ipEntity, Computer, Direction, ProcessName, SourceIp, DestinationIp, RemoteIp, Protocol, DestinationPort, NetworkSourceIP, Type, Url

Stage 18: extend

| extend timestamp = VMConnection_TimeGenerated, HostName = tostring(split(Computer, '.', 0)[0]), DnsDomain = tostring(strcat_array(array_slice(split(Computer, '.'), 1, -1), '.'))

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
TI_ipEntitycidr_match10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 169.254.0.0/16, 127.0.0.0/8
TI_ipEntitystarts_with127.
TI_ipEntitystarts_with::
TI_ipEntitystarts_withfe80

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
IndicatorTypein
  • ipv4-addr transforms: cased
  • ipv6-addr transforms: cased
  • network-traffic transforms: cased
VMConnection_TimeGeneratedlt
  • ValidUntil transforms: cased
ValidUntilis_null
  • (no value, null check)

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

FieldSource
ActivityGroupNamesproject
Computerproject
Confidenceproject
Descriptionproject
DestinationIpproject
DestinationPortproject
Directionproject
Idproject
NetworkSourceIPproject
ProcessNameproject
Protocolproject
RemoteIpproject
SourceIpproject
TI_ipEntityproject
Typeproject
Urlproject
VMConnection_TimeGeneratedproject
ValidUntilproject
DnsDomainextend
HostNameextend
timestampextend