detection.wiki

Detection rules › Kusto

API - Rate limiting

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

'42Crunch API protection against rate limiting'

MITRE ATT&CK coverage

TacticTechniques
Impact

Rule body

id: b808063b-07d5-432c-95d0-8900da61cce9
name: API - Rate limiting
description: |
  '42Crunch API protection against rate limiting'
severity: Medium
requiredDataConnectors:
  - connectorId: 42CrunchAPIProtection
    dataTypes:
      - FortyTwoCrunchAPIProtection
  - connectorId: FortyTwoCrunchAPIProtection
    dataTypes:
      - FortyTwoCrunchAPIProtection
queryFrequency: 5m
queryPeriod: 5m
triggerOperator: gt
triggerThreshold: 0
eventGroupingSettings:
  aggregationKind: SingleAlert
status: Available
tactics:
  - Impact
relevantTechniques:
  - T1499
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" and Status == 429;
  let rateLimitCount = (toscalar(firstRec | count));
  let recCount = iff((rateLimitCount > 20), 1, 0);
  firstRec | top recCount by Timestamp desc;
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

Parameters

let recCount = iff((rateLimitCount > 20), 1, 0);

let firstRec is inlined into the numbered stages below.

Let binding: rateLimitCount

let rateLimitCount = (toscalar(firstRec | count));

Stages 1 to 4 define let firstRec (the rule's main pipeline source); stage 5 runs on it.

Stage 1: source

FortyTwoCrunchAPIProtection

Stage 2: where

| where 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/login" and Status == 429

Stage 5: top

firstRec
| top recCount by Timestamp desc;

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Statuseq
  • 429
field:"Status" kind:eq value:"429"
UriPathmatch
  • /api/login transforms: term
field:"UriPath" kind:match value:"/api/login"