Detection rules › Kusto

TI map IP entity to OfficeActivity

Severity
medium
Time window
14d
Group by
IPAddress, Id, ObservableValue, 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: f50280e5-5eb1-4e95-99fd-9d584a987bdd
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:
      - ThreatIntelIndicators
  - connectorId: ThreatIntelligenceTaxii
    dataTypes:
      - ThreatIntelIndicators
  - connectorId: MicrosoftDefenderThreatIntelligence
    dataTypes:
      - ThreatIntelIndicators
  - 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(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 = NetworkSourceIP
    | where TI_ipEntity in (ActivityIPs)
    | extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
    | summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
    | where IsActive and (ValidUntil > now() or isempty(ValidUntil))
    | extend Description = tostring(parse_json(Data).description)
    | where Description !contains_cs "State: inactive;" and Description !contains_cs "State: falsepos;");
  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 (OfficeActivity_)
    on $left.TI_ipEntity == $right.IPAddress
  // Filter out OfficeActivity events that occurred after the expiration of the corresponding indicator
  | where OfficeActivity_TimeGenerated < ValidUntil
  // Group the results by IndicatorId and keep the OfficeActivity event with the latest timestamp
  | summarize OfficeActivity_TimeGenerated = arg_max(OfficeActivity_TimeGenerated, *) by Id
  // Select the desired output fields
  | extend Description = tostring(parse_json(Data).description)
  | extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
  | project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, TI_ipEntity, ClientIP, UserId, Operation, ResultStatus, RecordType, OfficeObjectId, NetworkSourceIP, Type, Url
  | 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: 1.4.7
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

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

| extend TI_ipEntity = NetworkSourceIP

Stage 8: where

| where TI_ipEntity in (ActivityIPs)

References ActivityIPs (defined above).

Stage 9: extend

| extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
Url =
ifObservableKey == "url:value"ObservableValue
else""

Stage 10: summarize

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

Stage 11: where

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

Stage 12: extend

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

Stage 13: where

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

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

Stage 14: project-reorder

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

Stage 15: join

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

Stage 16: where

| where OfficeActivity_TimeGenerated < ValidUntil

Stage 17: summarize

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

Stage 18: extend

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

Stage 19: extend

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

Stage 20: project

| project OfficeActivity_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, TI_ipEntity, ClientIP, UserId, Operation, ResultStatus, RecordType, OfficeObjectId, NetworkSourceIP, Type, Url

Stage 21: 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
ClientIPis_not_null
  • (no value, null check)
IndicatorTypein
  • ipv4-addr transforms: cased
  • ipv6-addr transforms: cased
  • network-traffic transforms: cased
OfficeActivity_TimeGeneratedlt
  • ValidUntil transforms: cased
TI_ipEntityin
  • ActivityIPs 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
ClientIPproject
Confidenceproject
Descriptionproject
Idproject
NetworkSourceIPproject
OfficeActivity_TimeGeneratedproject
OfficeObjectIdproject
Operationproject
RecordTypeproject
ResultStatusproject
TI_ipEntityproject
Typeproject
Urlproject
UserIdproject
ValidUntilproject
Nameextend
UPNSuffixextend
timestampextend