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

OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/AuditLogs/UserStatechangedfromGuesttoMember.yaml
queryPeriod: 1d
kind: Scheduled
name: User State changed from Guest to Member
entityMappings:
- fieldMappings:
  - columnName: UpdatingAppName
    identifier: Name
  - columnName: UpdatingServicePrincipalId
    identifier: AadUserId
  entityType: Account
- fieldMappings:
  - columnName: UpdatingUserPrincipalName
    identifier: FullName
  - columnName: InitiatingAccountName
    identifier: Name
  - columnName: InitiatingAccountUPNSuffix
    identifier: UPNSuffix
  entityType: Account
- fieldMappings:
  - columnName: UpdatingUserAadUserId
    identifier: AadUserId
  entityType: Account
- fieldMappings:
  - columnName: UpdatedUserPrincipalName
    identifier: FullName
  - columnName: TargetAccountName
    identifier: Name
  - columnName: TargetAccountUPNSuffix
    identifier: UPNSuffix
  entityType: Account
- fieldMappings:
  - columnName: UpdatingUserIPAddress
    identifier: Address
  entityType: IP
tactics:
- Persistence
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
metadata:
  categories:
    domains:
    - Security - Others
    - Identity
  support:
    tier: Community
  source:
    kind: Community
  author:
    name: Microsoft Security Research
tags:
- AADSecOpsGuide
requiredDataConnectors:
- connectorId: AzureActiveDirectory
  dataTypes:
  - AuditLogs
queryFrequency: 1d
triggerThreshold: 0
version: 1.1.0
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])  
relevantTechniques:
- T1098
id: a09a0b8e-30fe-4ebf-94a0-cffe50f579cd
triggerOperator: gt

ARM