Azure AD Health Service Agents Registry Keys Access

Severity: medium
Author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC
Source: upstream

This detection uses Windows security events to detect suspicious access attempts to the registry key values and sub-keys of Azure AD Health service agents (e.g AD FS). Information from AD Health service agents can be used to potentially abuse some of the features provided by those services in the cloud (e.g. Federation). This detection requires an access control entry (ACE) on the system access control list (SACL) of the following securable object: HKLM:\SOFTWARE\Microsoft\ADHealthAgent. Make sure you set the SACL to propagate to its sub-keys.

MITRE ATT&CK coverage

Tactic	Techniques
Discovery	`T1012` Query Registry

Event coverage

Provider	Event ID	Title
Security-Auditing	4656	A handle to an object was requested.
Security-Auditing	4663	An attempt was made to access an object.

Stages and Predicates

Stage 1: `selection`

ObjectName: '\REGISTRY\MACHINE\SOFTWARE\Microsoft\ADHealthAgent'
ObjectType: Key

Stage 2: `not filter`

or:
ProcessName|contains: 'Microsoft.Identity.Health.Adfs.DiagnosticsAgent.exe'
ProcessName|contains: 'Microsoft.Identity.Health.Adfs.InsightsService.exe'
ProcessName|contains: 'Microsoft.Identity.Health.Adfs.MonitoringAgent.Startup.exe'
ProcessName|contains: 'Microsoft.Identity.Health.Adfs.PshSurrogate.exe'
ProcessName|contains: 'Microsoft.Identity.Health.Common.Clients.ResourceMonitor.exe'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

Field	Kind	Values
`ObjectName`	eq	`\REGISTRY\MACHINE\SOFTWARE\Microsoft\ADHealthAgent`
`ObjectType`	eq	`Key` corpus 3 (sigma 3)
`ProcessName`	match	`Microsoft.Identity.Health.Adfs.DiagnosticsAgent.exe` corpus 2 (sigma 2) `Microsoft.Identity.Health.Adfs.InsightsService.exe` corpus 2 (sigma 2) `Microsoft.Identity.Health.Adfs.MonitoringAgent.Startup.exe` corpus 2 (sigma 2) `Microsoft.Identity.Health.Adfs.PshSurrogate.exe` corpus 2 (sigma 2) `Microsoft.Identity.Health.Common.Clients.ResourceMonitor.exe` corpus 2 (sigma 2)

Neighbors

Often fire together

Rules that target events appearing in the same incident timelines. They pattern-match on adjacent steps of the same TTP, so an alert from one is often paired with alerts from these. Useful for triage context and for assembling chained-detection rules.

Azure AD Health Monitoring Agent Registry Keys Access [sigma]
Processes Accessing the Microphone and Webcam [sigma]
LSASS Access From Non System Account [sigma]
WCE wceaux.dll Access [sigma]
Potential Secure Deletion with SDelete [sigma]
Potentially Suspicious AccessMask Requested From LSASS [sigma]
SysKey Registry Keys Access [sigma]
Sysmon Channel Reference Deletion [sigma]

Share event IDs (chain-detection candidates)

Rules that observe the same Windows event-ID pairs as this one. If you're authoring a multi-stage / sequence rule that spans these events, these are the existing detections that already cover one or both endpoints.

Azure AD Health Monitoring Agent Registry Keys Access [sigma]
Processes Accessing the Microphone and Webcam [sigma]
LSASS Access From Non System Account [sigma]
WCE wceaux.dll Access [sigma]
Potential Secure Deletion with SDelete [sigma]
Potentially Suspicious AccessMask Requested From LSASS [sigma]
SysKey Registry Keys Access [sigma]
Windows Defender Exclusion Registry Key - Write Access Requested [sigma]