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Detection rules › Kusto

API - Rate limiting

Status
available
Severity
low
Time window
7d
Source
github.com/Azure/Azure-Sentinel

'42Crunch API protection against first-time access'

MITRE ATT&CK coverage

TacticTechniques
Initial Access
Discovery

Rule body

id: c6258d51-7b82-4942-8293-94c1dcf91595
name: API - Rate limiting
description: |
  '42Crunch API protection against first-time access'
severity: Low
requiredDataConnectors:
  - connectorId: 42CrunchAPIProtection
    dataTypes:
      - FortyTwoCrunchAPIProtection
  - connectorId: FortyTwoCrunchAPIProtection
    dataTypes:
      - FortyTwoCrunchAPIProtection
queryFrequency: 1d
queryPeriod: 7d
triggerOperator: gt
triggerThreshold: 0
eventGroupingSettings:
  aggregationKind: SingleAlert
status: Available
tactics:
  - Discovery
  - InitialAccess
relevantTechniques:
  - T1087
  - T1190
query: |
  let firstRec = FortyTwoCrunchAPIProtection
  | where TimeGenerated >= ago(5m) 
  | project-away NonBlockingMode, SourcePort, DestinationPort, Query, ApiId, RequestHeader, ResponseHeader, Errors, EventType, Uuid
  | where UriPath has "/api/login" |
  top 1 by Timestamp desc;
  let ipAddress = toscalar(firstRec | summarize by SourceIp);
  let secondRec = FortyTwoCrunchAPIProtection
  | where TimeGenerated >= ago(7d) 
  | project-away NonBlockingMode, SourcePort, DestinationPort, Query, ApiId, RequestHeader, ResponseHeader, Errors, EventType, Uuid
  | where UriPath has "/api/login" and SourceIp == ipAddress;
  let recCount = iff((toscalar(secondRec | count) > 1), 0, 1);
  secondRec | take recCount
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

Stage 0: let

let firstRec = FortyTwoCrunchAPIProtection
| where TimeGenerated >= ago(5m) 
| project-away NonBlockingMode, SourcePort, DestinationPort, Query, ApiId, RequestHeader, ResponseHeader, Errors, EventType, Uuid
| where UriPath has "/api/login" |
top 1 by Timestamp desc;
let ipAddress = toscalar(firstRec | summarize by SourceIp);
let secondRec = FortyTwoCrunchAPIProtection <inlined as stages below>;
let recCount = iff((toscalar(secondRec | count) > 1), 0, 1);

Stage 1: source

FortyTwoCrunchAPIProtection

Stage 2: where

| where TimeGenerated >= ago(7d)

Stage 3: project-away

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

Stage 4: where

| where UriPath has "/api/login" and SourceIp == ipAddress

Stage 5: take

| take recCount

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
SourceIpcross_field_compare
  • ipAddress transforms: op:eq
field:"src_ip" kind:cross_field_compare value:"ipAddress"
UriPathmatch
  • /api/login transforms: term
field:"UriPath" kind:match value:"/api/login"