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Detection rules › Kusto

API - Anomaly Detection

Status
available
Severity
low
Time window
5m
Source
github.com/Azure/Azure-Sentinel

'42Crunch API protection anomaly detection'

MITRE ATT&CK coverage

TacticTechniques
Reconnaissance

Rule body

id: 2c59e609-e0a0-4e8e-adc5-ab4224be8a36
name: API - Anomaly Detection
description: |
  '42Crunch API protection anomaly detection'
severity: Low
requiredDataConnectors:
  - connectorId: 42CrunchAPIProtection
    dataTypes:
      - FortyTwoCrunchAPIProtection
  - connectorId: FortyTwoCrunchAPIProtection
    dataTypes:
      - FortyTwoCrunchAPIProtection
queryFrequency: 5m
queryPeriod: 5m
triggerOperator: gt
triggerThreshold: 0
eventGroupingSettings:
  aggregationKind: SingleAlert
status: Available
tactics:
  - Reconnaissance
relevantTechniques:
  - T1593
  - T1589
query: |
  let infoRec = FortyTwoCrunchAPIProtection
  | where TimeGenerated >= ago(5m) 
  | project-away NonBlockingMode, SourcePort, DestinationPort, Query, ApiId, RequestHeader, ResponseHeader, Errors, EventType, Uuid
  | where UriPath has "/api/users/info" and Status == 200;
  let timestamp = toscalar(infoRec | top 1 by Timestamp desc | summarize by Timestamp);
  let activityRec = FortyTwoCrunchAPIProtection
    | where Timestamp < timestamp and TimeGenerated >= ago(5m)
    | project-away NonBlockingMode, SourcePort, DestinationPort, Query, ApiId, RequestHeader, ResponseHeader, Errors, EventType, Uuid
    | where UriPath has "/api/users/activity" and Status == 200;
  activityRec
customDetails:
entityMappings:
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: SourceIp
  - entityType: Host
    fieldMappings:
      - identifier: HostName
        columnName: Hostname
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: InstanceName
version: 3.0.1
kind: Scheduled

Stages and Predicates

let activityRec is inlined into the numbered stages below.

Let binding: infoRec

let infoRec = FortyTwoCrunchAPIProtection
| where TimeGenerated >= ago(5m) 
| project-away NonBlockingMode, SourcePort, DestinationPort, Query, ApiId, RequestHeader, ResponseHeader, Errors, EventType, Uuid
| where UriPath has "/api/users/info" and Status == 200;

Let binding: timestamp used in Stage 2

let timestamp = toscalar(infoRec | top 1 by Timestamp desc | summarize by Timestamp);

Stage 1: source

FortyTwoCrunchAPIProtection

Stage 2: where

| where Timestamp < timestamp and TimeGenerated >= ago(5m)

Stage 3: project-away

| project-away NonBlockingMode, SourcePort, DestinationPort, Query, ApiId, RequestHeader, ResponseHeader, Errors, EventType, Uuid

Stage 4: where

| where UriPath has "/api/users/activity" and Status == 200

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Statuseq
  • 200
field:"Status" kind:eq value:"200"
Timestampcross_field_compare
  • timestamp transforms: op:lt
field:"Timestamp" kind:cross_field_compare value:"timestamp"
UriPathmatch
  • /api/users/activity transforms: term
field:"UriPath" kind:match value:"/api/users/activity"