Detection rules › Kusto

TI map IP entity to OfficeActivity

Severity
medium
Time window
14d
Group by
IPAddress, IndicatorId, 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 OfficeActivity.

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1071 Application Layer Protocol

Rule body kusto

id: f15370f4-c6fa-42c5-9be4-1d308f40284e
name: TI map IP entity to OfficeActivity
description: |
  This query maps any IP indicators of compromise (IOCs) from threat intelligence (TI), by searching for matches in OfficeActivity.
severity: Medium
requiredDataConnectors:
  - connectorId: ThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelligenceIndicator
  - connectorId: Office365
    dataTypes:
      - OfficeActivity
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - CommandAndControl
relevantTechniques:
  - T1071
query: |
  let dt_lookBack = 1h; // Look back 1 hour for OfficeActivity events
  let ioc_lookBack = 14d; // Look back 14 days for threat intelligence indicators
  let OfficeActivity_ = materialize(OfficeActivity
    | where isnotempty(ClientIP)
    | where TimeGenerated >= ago(dt_lookBack)
    | extend ClientIPValues = extract_all(@'\[?(::ffff:)?(?P<IPAddress>(\d+\.\d+\.\d+\.\d+)|[^\]%]+)(%\d+)?\]?([-:](?P<Port>\d+))?', dynamic(["IPAddress", "Port"]), ClientIP)[0]
    | extend IPAddress = iff(array_length(ClientIPValues) > 0, tostring(ClientIPValues[0]), '')
    | project-rename OfficeActivity_TimeGenerated = TimeGenerated);
  let ActivityIPs = OfficeActivity_ | summarize IPs = make_list(IPAddress);
  // Fetch threat intelligence indicators related to IP addresses
  let IP_Indicators = materialize(ThreatIntelligenceIndicator
    | where isnotempty(NetworkIP) or isnotempty(EmailSourceIpAddress) or isnotempty(NetworkDestinationIP) or isnotempty(NetworkSourceIP)
    | where TimeGenerated >= ago(ioc_lookBack)
    | extend TI_ipEntity = coalesce(NetworkDestinationIP, NetworkSourceIP, EmailSourceIpAddress)
    | where TI_ipEntity in (ActivityIPs)
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId
    | where  Active == true and ExpirationDateTime > now()
    | where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;");
  IP_Indicators
  // 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 (OfficeActivity_)
    on $left.TI_ipEntity == $right.IPAddress
  // Filter out OfficeActivity events that occurred after the expiration of the corresponding indicator
  | where OfficeActivity_TimeGenerated < ExpirationDateTime
  // Group the results by IndicatorId and keep the OfficeActivity event with the latest timestamp
  | summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by IndicatorId
  // Select the desired output fields
  | project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore, TI_ipEntity, ClientIP, UserId, Operation, ResultStatus, RecordType, OfficeObjectId, NetworkIP, NetworkDestinationIP, NetworkSourceIP, EmailSourceIpAddress, Type
  | extend timestamp = OfficeActivity_TimeGenerated, Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: UserId
      - identifier: Name
        columnName: Name
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: TI_ipEntity
  - entityType: URL
    fieldMappings:
      - identifier: Url
        columnName: Url
version: 1.4.3
kind: Scheduled

Stages and Predicates

Parameters

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

Let binding: OfficeActivity_

let OfficeActivity_ = materialize(OfficeActivity
  | where isnotempty(ClientIP)
  | where TimeGenerated >= ago(dt_lookBack)
  | extend ClientIPValues = extract_all(@'\[?(::ffff:)?(?P<IPAddress>(\d+\.\d+\.\d+\.\d+)|[^\]%]+)(%\d+)?\]?([-:](?P<Port>\d+))?', dynamic(["IPAddress", "Port"]), ClientIP)[0]
  | extend IPAddress = iff(array_length(ClientIPValues) > 0, tostring(ClientIPValues[0]), '')
  | project-rename OfficeActivity_TimeGenerated = TimeGenerated);

Derived from dt_lookBack.

Let binding: ActivityIPs

let ActivityIPs = OfficeActivity_ | summarize IPs = make_list(IPAddress);

Derived from OfficeActivity_.

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

Stage 1: source

ThreatIntelligenceIndicator

Stage 2: where

| where isnotempty(NetworkIP) or isnotempty(EmailSourceIpAddress) or isnotempty(NetworkDestinationIP) or isnotempty(NetworkSourceIP)

Stage 3: where

| where TimeGenerated >= ago(ioc_lookBack)

Stage 4: extend

| extend TI_ipEntity = coalesce(NetworkDestinationIP, NetworkSourceIP, EmailSourceIpAddress)

Stage 5: where

| where TI_ipEntity in (ActivityIPs)

References ActivityIPs (defined above).

Stage 6: summarize

| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by IndicatorId

Stage 7: where

| where  Active == true and ExpirationDateTime > now()

Stage 8: where

| where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;"

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

Stage 9: join

IP_Indicators
| join kind=innerunique (OfficeActivity_)
  on $left.TI_ipEntity == $right.IPAddress

Stage 10: where

| where OfficeActivity_TimeGenerated < ExpirationDateTime

Stage 11: summarize

| summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by IndicatorId

Stage 12: project

| project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, IndicatorId, ThreatType, Url, ExpirationDateTime, ConfidenceScore, TI_ipEntity, ClientIP, UserId, Operation, ResultStatus, RecordType, OfficeObjectId, NetworkIP, NetworkDestinationIP, NetworkSourceIP, EmailSourceIpAddress, Type

Stage 13: extend

| extend timestamp = OfficeActivity_TimeGenerated, Name = tostring(split(UserId, '@', 0)[0]), UPNSuffix = tostring(split(UserId, '@', 1)[0])

Exclusions

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

FieldKindExcluded values
DescriptioncontainsState: falsepos;
DescriptioncontainsState: inactive;

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
Activeeq
  • true transforms: cased
ClientIPis_not_null
  • (no value, null check)
EmailSourceIpAddressis_not_null
  • (no value, null check)
NetworkDestinationIPis_not_null
  • (no value, null check)
NetworkIPis_not_null
  • (no value, null check)
NetworkSourceIPis_not_null
  • (no value, null check)
OfficeActivity_TimeGeneratedlt
  • ExpirationDateTime transforms: cased
TI_ipEntityin
  • ActivityIPs transforms: cased

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
ClientIPproject
ConfidenceScoreproject
Descriptionproject
EmailSourceIpAddressproject
ExpirationDateTimeproject
IndicatorIdproject
NetworkDestinationIPproject
NetworkIPproject
NetworkSourceIPproject
OfficeActivity_TimeGeneratedproject
OfficeObjectIdproject
Operationproject
RecordTypeproject
ResultStatusproject
TI_ipEntityproject
ThreatTypeproject
Typeproject
Urlproject
UserIdproject
Nameextend
UPNSuffixextend
timestampextend