Detection rules › Kusto

BTP - Failed access attempts across multiple BAS subaccounts

Status
available
Severity
medium
Time window
1h
Group by
UserName
Source
github.com/Azure/Azure-Sentinel

Identifies failed Business Application Studio access attempts over a predefined number of subaccounts.

MITRE ATT&CK coverage

TacticTechniques
ReconnaissanceT1595 Active Scanning
DiscoveryT1526 Cloud Service Discovery

Rule body kusto

id: 74b243a6-3046-48aa-8b03-e43b3c529cc1
kind: Scheduled
name: BTP - Failed access attempts across multiple BAS subaccounts
description: Identifies failed Business Application Studio access attempts over a
  predefined number of subaccounts.
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: SAPBTPAuditEvents
    dataTypes:
      - SAPBTPAuditLog_CL
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Reconnaissance
  - Discovery
relevantTechniques:
  - T1595
  - T1526
query: |
  let subaccount_detection_threshold = 3;
  SAPBTPAuditLog_CL
  | where Category == "audit.security-events" and Message has "Unauthorized access attempt"
  | summarize Start=min(UpdatedOn), End=max(UpdatedOn), Tenants = make_set(Tenant, 100) by UserName
  | where array_length(Tenants) > subaccount_detection_threshold
  | project Start, End, UserName, Tenants, CloudApp = "SAP BTP"
  | extend AccountName = split(UserName, "@")[0], UPNSuffix = split(UserName, "@")[1]
eventGroupingSettings:
  aggregationKind: SingleAlert
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: CloudApplication
    fieldMappings:
      - identifier: Name
        columnName: CloudApp
alertDetailsOverride:
  alertDisplayNameFormat: BTP - Unauthorized access attempt to multiple tenants
  alertDescriptionFormat: '{{UserName}} attempted, and failed, to log into multiple
    Business Application Studio dev spaces. Tenants accessed: {{Tenants}}'
version: 3.0.5

Stages and Predicates

Parameters

let subaccount_detection_threshold = 3;

Stage 1: source

SAPBTPAuditLog_CL

Stage 2: where

| where Category == "audit.security-events" and Message has "Unauthorized access attempt"

Stage 3: summarize

| summarize Start=min(UpdatedOn), End=max(UpdatedOn), Tenants = make_set(Tenant, 100) by UserName
Threshold
gt 3

Stage 4: where

| where array_length(Tenants) > subaccount_detection_threshold

Stage 5: project

| project Start, End, UserName, Tenants, CloudApp = "SAP BTP"

Stage 6: extend

| extend AccountName = split(UserName, "@")[0], UPNSuffix = split(UserName, "@")[1]

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
Categoryeq
  • audit.security-events transforms: cased
Messagematch
  • Unauthorized access attempt transforms: term
Tenantsgt
  • 3 transforms: array_length

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
CloudAppproject
Endproject
Startproject
Tenantsproject
UserNameproject
AccountNameextend
UPNSuffixextend