New access credential added to Application or Service Principal

id: 79566f41-df67-4e10-a703-c38a6213afd8
name: New access credential added to Application or Service Principal
description: |
  'This will alert when an admin or app owner account adds a new credential to an Application or Service Principal where a verify KeyCredential was already present for the app.
  If a threat actor obtains access to an account with sufficient privileges and adds the alternate authentication material triggering this event, the threat actor can now authenticate as the Application or Service Principal using this credential.
  Additional information on OAuth Credential Grants can be found in RFC 6749 Section 4.4 or https://docs.microsoft.com/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow
  For further information on AuditLogs please see https://docs.microsoft.com/azure/active-directory/reports-monitoring/reference-audit-activities.'
severity: Medium
requiredDataConnectors:
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AuditLogs
queryFrequency: 1h
queryPeriod: 1h
triggerOperator: gt
triggerThreshold: 0
status: Available
tactics:
  - DefenseEvasion
relevantTechniques:
  - T1550.001
tags:
  - Solorigate
  - NOBELIUM
query: |
  AuditLogs
  | where OperationName has_any ("Add service principal", "Certificates and secrets management") // captures "Add service principal", "Add service principal credentials", and "Update application - Certificates and secrets management" events
  | where Result =~ "success"
  | where tostring(InitiatedBy.user.userPrincipalName) has "@" or tostring(InitiatedBy.app.displayName) has "@"
  | mv-apply TargetResource = TargetResources on 
    (
        where TargetResource.type =~ "Application"
        | extend targetDisplayName = tostring(TargetResource.displayName),
                 targetId = tostring(TargetResource.id),
                 targetType = tostring(TargetResource.type),
                 keyEvents = TargetResource.modifiedProperties
    )
  | mv-apply Property = keyEvents on 
    (
        where Property.displayName =~ "KeyDescription"
        | extend new_value_set = parse_json(tostring(Property.newValue)),
                 old_value_set = parse_json(tostring(Property.oldValue))
    )
  | where old_value_set != "[]"
  | extend diff = set_difference(new_value_set, old_value_set)
  | where isnotempty(diff)
  | parse diff with * "KeyIdentifier=" keyIdentifier:string ",KeyType=" keyType:string ",KeyUsage=" keyUsage:string ",DisplayName=" keyDisplayName:string "]" *
  | where keyUsage =~ "Verify"
  | mv-apply AdditionalDetail = AdditionalDetails on 
    (
        where AdditionalDetail.key =~ "User-Agent"
        | extend UserAgent = tostring(AdditionalDetail.value)
    )
  | extend InitiatingAppName = tostring(InitiatedBy.app.displayName)
  | extend InitiatingAppServicePrincipalId = tostring(InitiatedBy.app.servicePrincipalId)
  | extend InitiatingUserPrincipalName = tostring(InitiatedBy.user.userPrincipalName)
  | extend InitiatingAadUserId = tostring(InitiatedBy.user.id)
  | extend InitiatingIpAddress = tostring(iff(isnotempty(InitiatedBy.user.ipAddress), InitiatedBy.user.ipAddress, InitiatedBy.app.ipAddress))
  // The below line is currently commented out but Microsoft Sentinel users can modify this query to show only Application or only Service Principal events in their environment
  //| where targetType =~ "Application" // or targetType =~ "ServicePrincipal"
  | project-away diff, new_value_set, old_value_set
  | project-reorder TimeGenerated, OperationName, InitiatingAppName, InitiatingAppServicePrincipalId, InitiatingUserPrincipalName, InitiatingAadUserId, InitiatingIpAddress, UserAgent, targetDisplayName, targetId, targetType, keyDisplayName, keyType, keyUsage, keyIdentifier, CorrelationId, TenantId
  | extend Name = tostring(split(InitiatingUserPrincipalName,'@',0)[0]), UPNSuffix = tostring(split(InitiatingUserPrincipalName,'@',1)[0])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: InitiatingUserPrincipalName
      - identifier: Name
        columnName: Name
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: InitiatingIpAddress
  - entityType: Account
    fieldMappings:
      - identifier: AadUserId
        columnName: InitiatingAadUserId
  - entityType: Account
    fieldMappings:
      - identifier: AadUserId
        columnName: InitiatingAppServicePrincipalId
version: 1.1.2
kind: Scheduled