name: Azure AD User ImmutableId Attribute Updated
id: 0c0badad-4536-4a84-a561-5ff760f3c00e
version: 1
date: '2022-09-02'
author: Mauricio Velazco, Splunk
type: TTP
datamodel: []
description: The following analytic identifies the modification of the SourceAnchor (also called ImmutableId) attribute for an Azure Active Directory user. Updating this attribute
  is a step required to set up the Azure Active Directory identity federation backdoor technique discovered by security researcher Nestori Syynimaa.
  Similar to Active Directory, Azure AD uses the concept of domains to manage directories of identities. A new Azure AD tenant will initially contain a
  single domain that is commonly called the `cloud-only` onmicrosoft.com domain. Organizations can also add their registered custom domains to Azure AD for
  email addresses to match the organizations domain name. If the organization intends to use a third-party identity provider such as ADFS for authentication, 
  the added custom domains can be configured as federated. An adversary who has obtained privileged access to an Azure AD tenant may leverage this technique
  to establish persistence and be able to authenticate to Azure AD impersonating any user and bypassing the requirement to have a valid password and/or perform MFA.
search: ' `azuread` body.operationName="Update user" body.properties.targetResources{}.modifiedProperties{}.displayName=SourceAnchor
  | rename body.properties.* as *
  | rename targetResources{}.userPrincipalName as userPrincipalName 
  | rename initiatedBy.user.userPrincipalName as initiatedBy
  | rename body.callerIpAddress as callerIpAddress
  | rename targetResources{}.modifiedProperties{}.newValue as modifiedProperties
  | stats values(userPrincipalName) values(modifiedProperties) by _time, initiatedBy, callerIpAddress, result, body.operationName
  | `azure_ad_user_immutableid_attribute_updated_filter`'
how_to_implement: You must install the latest version of Splunk Add-on for Microsoft Cloud Services from Splunkbase(https://splunkbase.splunk.com/app/3110/#/details). You must be ingesting Azure Active Directory events into your Splunk environment. 
  Specifically, this analytic leverages the AuditLogs log category.
known_false_positives: The SourceAnchor (also called ImmutableId) Azure AD attribute has legitimate uses for directory synchronization. Investigate and filter as needed.
references:
- https://docs.microsoft.com/en-us/azure/active-directory/hybrid/plan-connect-design-concepts
- https://www.mandiant.com/resources/remediation-and-hardening-strategies-microsoft-365-defend-against-apt29-v13
- https://o365blog.com/post/federation-vulnerability/
- https://www.inversecos.com/2021/11/how-to-detect-azure-active-directory.html
- https://www.mandiant.com/resources/blog/detecting-microsoft-365-azure-active-directory-backdoors
- https://attack.mitre.org/techniques/T1098/
tags:
  analytic_story:
  - Azure Active Directory Persistence
  asset_type: Azure Active Directory
  cis20:
  - CIS 3
  - CIS 5
  - CIS 16
  confidence: 90
  context:
  - Source:Cloud Data
  - Stage:Persistence
  dataset:
  - https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1098/azure_ad_set_immutableid/azure-audit.log
  impact: 50
  kill_chain_phases:
  - Installation
  - Actions on Objectives
  message: The SourceAnchor or ImmutableID attribute has been modified for user $userPrincipalName$ by $initiatedBy$
  mitre_attack_id:
  - T1098
  nist:
  - DE.CM
  observable:
  - name: userPrincipalName
    type: User
    role:
    - Victim
  - name: initiatedBy
    type: User
    role:
    - Attacker
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  risk_score: 45
  security_domain: threat