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Azure Active Directory Hybrid Health AD FS New Server — Sigma Rule

Sigma rule 288a39fc-4914-4831-9ada-270e9dc12cb4. Azure Active Directory Hybrid Health AD FS New Server — Sigma Rule. This detection uses azureactivity logs (Administrative category) to identify the creation or update of a server instance in an Azure AD Hybrid health AD FS service. A threat actor can create a new AD Health ADFS service and create a fake server instance to spoof AD FS signing logs. There is no need to compromise an on-prem AD FS server. This can be done programmatically via HTTP requests to Azure.

Rule metadata and linked tags

testmediumazureactivitylogsattack.defense-impairmentattack.t1578

Author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC. Source status: test; severity: medium. Source dates: 2021-08-26 / 2023-10-11.

{
  "product": "azure",
  "service": "activitylogs"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 4c84f7a91522126ab2d9ecbb04978d62347476e595959e532ca35aefd8c7fea7

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Azure Active Directory Hybrid Health AD FS New Server
id: 288a39fc-4914-4831-9ada-270e9dc12cb4
status: test
description: |
    This detection uses azureactivity logs (Administrative category) to identify the creation or update of a server instance in an Azure AD Hybrid health AD FS service.
    A threat actor can create a new AD Health ADFS service and create a fake server instance to spoof AD FS signing logs. There is no need to compromise an on-prem AD FS server.
    This can be done programmatically via HTTP requests to Azure.
references:
    - https://o365blog.com/post/hybridhealthagent/
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC
date: 2021-08-26
modified: 2023-10-11
tags:
    - attack.defense-impairment
    - attack.t1578
logsource:
    product: azure
    service: activitylogs
detection:
    selection:
        CategoryValue: 'Administrative'
        ResourceProviderValue: 'Microsoft.ADHybridHealthService'
        ResourceId|contains: 'AdFederationService'
        OperationNameValue: 'Microsoft.ADHybridHealthService/services/servicemembers/action'
    condition: selection
falsepositives:
    - Legitimate AD FS servers added to an AAD Health AD FS service instance
level: medium

Original YAML and metadata in JSON

False positives

  • Legitimate AD FS servers added to an AAD Health AD FS service instance

Source references

Connected ecosystem references

Exact source-tagged techniques

Telemetry review

Read the original logsource above, then inspect the linked detection workspaces for technique-level sensor context. No per-rule telemetry equivalence is inferred.

Pinned research references. No browser attack runner, live simulation result or validated detector is asserted. Source mappings and validation limits are preserved. ATT&CK / Atomic provenance · Detection provenance.