User State changed from Guest to Member

Severity: medium
Time window: 1d
Author: Microsoft Security Research
Source: github.com/Azure/Azure-Sentinel

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

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1098` Account Manipulation

Event coverage

Provider	Event
Entra-AuditLogs	Update user

Rule body kusto

id: a09a0b8e-30fe-4ebf-94a0-cffe50f579cd
name: 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
requiredDataConnectors:
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AuditLogs
queryFrequency: 1d
queryPeriod: 1d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - Persistence
relevantTechniques:
  - T1098
tags:
  - AADSecOpsGuide
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])
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: UpdatingAppName
      - identifier: AadUserId
        columnName: UpdatingServicePrincipalId
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: UpdatingUserPrincipalName
      - identifier: Name
        columnName: InitiatingAccountName
      - identifier: UPNSuffix
        columnName: InitiatingAccountUPNSuffix
  - entityType: Account
    fieldMappings:
      - identifier: AadUserId
        columnName: UpdatingUserAadUserId
  - entityType: Account
    fieldMappings:
      - identifier: FullName
        columnName: UpdatedUserPrincipalName
      - identifier: Name
        columnName: TargetAccountName
      - identifier: UPNSuffix
        columnName: TargetAccountUPNSuffix
  - entityType: IP
    fieldMappings:
      - identifier: Address
        columnName: UpdatingUserIPAddress
version: 1.1.0
kind: Scheduled
metadata:
    source:
        kind: Community
    author:
        name: Microsoft Security Research
    support:
        tier: Community
    categories:
        domains: [ "Security - Others", "Identity" ]

Stages and Predicates

Stage 1: `source`

AuditLogs

Stage 2: `where`

| where OperationName =~ "Update user"

Stage 3: `where`

| where Result =~ "success"

Stage 4: `mv-expand`

| mv-expand TargetResources

Stage 5: `mv-expand`

| mv-expand TargetResources.modifiedProperties

Stage 6: `where`

| where TargetResources_modifiedProperties.displayName =~ "TargetId.UserType"

Stage 7: `extend` (7 consecutive steps)

| 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)

Stage 8: `project-reorder`

| project-reorder TimeGenerated, UpdatedUserPrincipalName, UpdatingUser

Stage 9: `where`

| where parse_json(tostring(TargetResources_modifiedProperties.newValue)) =~ "\"Member\"" and parse_json(tostring(TargetResources_modifiedProperties.oldValue)) =~ "\"Guest\""

Stage 10: `extend`

| extend InitiatingAccountName = tostring(split(UpdatingUserPrincipalName, "@")[0]), InitiatingAccountUPNSuffix = tostring(split(UpdatingUserPrincipalName, "@")[1])

Stage 11: `extend`

| extend TargetAccountName = tostring(split(UpdatedUserPrincipalName, "@")[0]), TargetAccountUPNSuffix = tostring(split(UpdatedUserPrincipalName, "@")[1])

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
`OperationName`	eq	`Update user`
`Result`	eq	`success`
`displayName`	eq	`TargetId.UserType`

Output fields

Fields the rule emits when it matches. Chronicle authors list these in the outcome block; they appear on the detection and $risk_score drives alerting. Sentinel / Defender XDR rules build them up through project / summarize / extend stages. Sentinel maps these into alert fields via entityMappings and customDetails; Defender XDR custom detections surface them as alert fields directly.

Field	Source
`UpdatingAppName`	`extend`
`UpdatingServicePrincipalId`	`extend`
`UpdatingUserPrincipalName`	`extend`
`UpdatingUserAadUserId`	`extend`
`UpdatingUserIPAddress`	`extend`
`UpdatingUser`	`extend`
`UpdatedUserPrincipalName`	`extend`
`InitiatingAccountName`	`extend`
`InitiatingAccountUPNSuffix`	`extend`
`TargetAccountName`	`extend`
`TargetAccountUPNSuffix`	`extend`

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`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)

User State changed from Guest to Member

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `mv-expand`

Stage 5: `mv-expand`

Stage 6: `where`

Stage 7: `extend` (7 consecutive steps)

Stage 8: `project-reorder`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `extend`

Indicators

Output fields

Keyboard shortcuts

Search operators

User State changed from Guest to Member

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: mv-expand

Stage 5: mv-expand

Stage 6: where

Stage 7: extend (7 consecutive steps)

Stage 8: project-reorder

Stage 9: where

Stage 10: extend

Stage 11: extend

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `mv-expand`

Stage 5: `mv-expand`

Stage 6: `where`

Stage 7: `extend` (7 consecutive steps)

Stage 8: `project-reorder`

Stage 9: `where`

Stage 10: `extend`

Stage 11: `extend`