User State changed from Guest to Member

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Id	a09a0b8e-30fe-4ebf-94a0-cffe50f579cd
Rulename	User State changed from Guest to Member
Description	Detects when a guest account in a tenant is converted to a member of the tenant. Monitoring guest accounts and the access they are provided is important to detect potential account abuse. Accounts converted to members should be investigated to ensure the activity was legitimate. Ref: https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#monitoring-for-failed-unusual-sign-ins
Severity	Medium
Tactics	Persistence
Techniques	T1098
Required data connectors	AzureActiveDirectory
Kind	Scheduled
Query frequency	1d
Query period	1d
Trigger threshold	0
Trigger operator	gt
Source Uri	https://github.com/Azure/Azure-Sentinel/blob/master/Detections/AuditLogs/UserStatechangedfromGuesttoMember.yaml
Version	1.1.0
Arm template	a09a0b8e-30fe-4ebf-94a0-cffe50f579cd.json

KQL

AuditLogs
  | where OperationName =~ "Update user"
  | where Result =~ "success"
  | mv-expand TargetResources
  | mv-expand TargetResources.modifiedProperties
  | where TargetResources_modifiedProperties.displayName =~ "TargetId.UserType"
  | extend UpdatingAppName = tostring(parse_json(tostring(InitiatedBy.app)).displayName)
  | extend UpdatingServicePrincipalId = tostring(parse_json(tostring(InitiatedBy.app)).servicePrincipalId)
  | extend UpdatingUserPrincipalName = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)
  | extend UpdatingUserAadUserId = tostring(parse_json(tostring(InitiatedBy.user)).id)
  | extend UpdatingUserIPAddress = tostring(parse_json(tostring(InitiatedBy.user)).ipAddress)
  | extend UpdatingUser = iif(isnotempty(UpdatingServicePrincipalId), UpdatingServicePrincipalId, UpdatingUserPrincipalName)
  | extend UpdatedUserPrincipalName = tostring(TargetResources.userPrincipalName)
  | project-reorder TimeGenerated, UpdatedUserPrincipalName, UpdatingUser
  | where parse_json(tostring(TargetResources_modifiedProperties.newValue)) =~ "\"Member\"" and parse_json(tostring(TargetResources_modifiedProperties.oldValue)) =~ "\"Guest\""
  | extend InitiatingAccountName = tostring(split(UpdatingUserPrincipalName, "@")[0]), InitiatingAccountUPNSuffix = tostring(split(UpdatingUserPrincipalName, "@")[1])
  | extend TargetAccountName = tostring(split(UpdatedUserPrincipalName, "@")[0]), TargetAccountUPNSuffix = tostring(split(UpdatedUserPrincipalName, "@")[1])

YAML

severity: Medium
triggerOperator: gt
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/AuditLogs/UserStatechangedfromGuesttoMember.yaml
tags:
- AADSecOpsGuide
id: a09a0b8e-30fe-4ebf-94a0-cffe50f579cd
metadata:
  categories:
    domains:
    - Security - Others
    - Identity
  author:
    name: Microsoft Security Research
  support:
    tier: Community
  source:
    kind: Community
entityMappings:
- fieldMappings:
  - identifier: Name
    columnName: UpdatingAppName
  - identifier: AadUserId
    columnName: UpdatingServicePrincipalId
  entityType: Account
- fieldMappings:
  - identifier: FullName
    columnName: UpdatingUserPrincipalName
  - identifier: Name
    columnName: InitiatingAccountName
  - identifier: UPNSuffix
    columnName: InitiatingAccountUPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: AadUserId
    columnName: UpdatingUserAadUserId
  entityType: Account
- fieldMappings:
  - identifier: FullName
    columnName: UpdatedUserPrincipalName
  - identifier: Name
    columnName: TargetAccountName
  - identifier: UPNSuffix
    columnName: TargetAccountUPNSuffix
  entityType: Account
- fieldMappings:
  - identifier: Address
    columnName: UpdatingUserIPAddress
  entityType: IP
kind: Scheduled
tactics:
- Persistence
queryFrequency: 1d
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AuditLogs
relevantTechniques:
- T1098
version: 1.1.0
description: |
  'Detects when a guest account in a tenant is converted to a member of the tenant.
    Monitoring guest accounts and the access they are provided is important to detect potential account abuse.
    Accounts converted to members should be investigated to ensure the activity was legitimate.
    Ref: https://docs.microsoft.com/azure/active-directory/fundamentals/security-operations-user-accounts#monitoring-for-failed-unusual-sign-ins'  
triggerThreshold: 0
query: |
  AuditLogs
    | where OperationName =~ "Update user"
    | where Result =~ "success"
    | mv-expand TargetResources
    | mv-expand TargetResources.modifiedProperties
    | where TargetResources_modifiedProperties.displayName =~ "TargetId.UserType"
    | extend UpdatingAppName = tostring(parse_json(tostring(InitiatedBy.app)).displayName)
    | extend UpdatingServicePrincipalId = tostring(parse_json(tostring(InitiatedBy.app)).servicePrincipalId)
    | extend UpdatingUserPrincipalName = tostring(parse_json(tostring(InitiatedBy.user)).userPrincipalName)
    | extend UpdatingUserAadUserId = tostring(parse_json(tostring(InitiatedBy.user)).id)
    | extend UpdatingUserIPAddress = tostring(parse_json(tostring(InitiatedBy.user)).ipAddress)
    | extend UpdatingUser = iif(isnotempty(UpdatingServicePrincipalId), UpdatingServicePrincipalId, UpdatingUserPrincipalName)
    | extend UpdatedUserPrincipalName = tostring(TargetResources.userPrincipalName)
    | project-reorder TimeGenerated, UpdatedUserPrincipalName, UpdatingUser
    | where parse_json(tostring(TargetResources_modifiedProperties.newValue)) =~ "\"Member\"" and parse_json(tostring(TargetResources_modifiedProperties.oldValue)) =~ "\"Guest\""
    | extend InitiatingAccountName = tostring(split(UpdatingUserPrincipalName, "@")[0]), InitiatingAccountUPNSuffix = tostring(split(UpdatingUserPrincipalName, "@")[1])
    | extend TargetAccountName = tostring(split(UpdatedUserPrincipalName, "@")[0]), TargetAccountUPNSuffix = tostring(split(UpdatedUserPrincipalName, "@")[1])  
queryPeriod: 1d
name: User State changed from Guest to Member

ARM