Azure AD Health Service Agents Registry Keys Access

Status: test
Severity: medium
Log source: product windows, service security
Author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC
Source: github.com/SigmaHQ/sigma

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

Rule body yaml

title: Azure AD Health Service Agents Registry Keys Access
id: 1d2ab8ac-1a01-423b-9c39-001510eae8e8
status: test
description: |
    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.
references:
    - https://o365blog.com/post/hybridhealthagent/
    - https://github.com/OTRF/Set-AuditRule/blob/c3dec5443414231714d850565d364ca73475ade5/rules/registry/aad_connect_health_service_agent.yml
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC
date: 2021-08-26
modified: 2022-10-09
tags:
    - attack.discovery
    - attack.t1012
logsource:
    product: windows
    service: security
detection:
    selection:
        EventID:
            - 4656
            - 4663
        ObjectType: 'Key'
        ObjectName: '\REGISTRY\MACHINE\SOFTWARE\Microsoft\ADHealthAgent'
    filter:
        ProcessName|contains:
            - 'Microsoft.Identity.Health.Adfs.DiagnosticsAgent.exe'
            - 'Microsoft.Identity.Health.Adfs.InsightsService.exe'
            - 'Microsoft.Identity.Health.Adfs.MonitoringAgent.Startup.exe'
            - 'Microsoft.Identity.Health.Adfs.PshSurrogate.exe'
            - 'Microsoft.Identity.Health.Common.Clients.ResourceMonitor.exe'
    condition: selection and not filter
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not filter

Stage 1: `selection`

selection:
    EventID:
        - 4656
        - 4663
    ObjectType: 'Key'
    ObjectName: '\REGISTRY\MACHINE\SOFTWARE\Microsoft\ADHealthAgent'

Stage 2: `not filter`

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

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`ProcessName`	match	`Microsoft.Identity.Health.Adfs.DiagnosticsAgent.exe`
`ProcessName`	match	`Microsoft.Identity.Health.Adfs.InsightsService.exe`
`ProcessName`	match	`Microsoft.Identity.Health.Adfs.MonitoringAgent.Startup.exe`
`ProcessName`	match	`Microsoft.Identity.Health.Adfs.PshSurrogate.exe`
`ProcessName`	match	`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 8 (sigma 4, kusto 4)

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Azure AD Health Service Agents Registry Keys Access

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Azure AD Health Service Agents Registry Keys Access

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection

Stage 2: not filter

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection`

Stage 2: `not filter`