Power Apps - Bulk sharing of Power Apps to newly created guest users

Status: available
Severity: medium
Time window: 14d
Group by: AppId, InvitedById, InvitedByUPN, InvitedId, TargetPrincipalId
Source: github.com/Azure/Azure-Sentinel

Identifies unusual bulk sharing, based on a predefined threshold in the query, of Power Apps to newly created Microsoft Entra guest users.

MITRE ATT&CK coverage

Tactic	Techniques
Resource Development	`T1587` Develop Capabilities
Initial Access	`T1566` Phishing
Lateral Movement	`T1534` Internal Spearphishing

Event coverage

Provider	Event
Entra-AuditLogs	Invite external user

Rule body kusto

id: 943acfa0-9285-4eb0-a9c0-42e36177ef19
kind: Scheduled
name: Power Apps - Bulk sharing of Power Apps to newly created guest users
description: Identifies unusual bulk sharing, based on a predefined threshold in the
  query, of Power Apps to newly created Microsoft Entra guest users.
severity: Medium
status: Available
requiredDataConnectors:
  - connectorId: PowerPlatformAdmin
    dataTypes:
      - PowerPlatformAdminActivity
  - connectorId: AzureActiveDirectory
    dataTypes:
      - AuditLogs
queryFrequency: 1h
queryPeriod: 14d
triggerOperator: gt
triggerThreshold: 0
tactics:
  - ResourceDevelopment
  - InitialAccess
  - LateralMovement
relevantTechniques:
  - T1587
  - T1566
  - T1534
query: |
  ////////////
  // threshold = If the number of unique accounts that a power app is shared with is greater than
  // threshold than it'll trigger an alert. A threshold of 5 is good to start with.
  // However, if this is giving too many false positives, please adjust the threshold.
  ////////////
  let threshold = 5;
  ////////////
  // Please replace the allowed_domains with a list of domains of your partners/sibling orgs
  // with whom you generally share power apps with. This will allow us to filter
  // legitimate bulk sharing attempts. Avoid using domains such as gmail, outlook, etc.
  ///////////
  let allowed_domains = pack_array("contoso.com");
  let query_frequency = 1h;
  let query_lookback = 14d;
  PowerPlatformAdminActivity
  | where TimeGenerated >= ago(query_frequency)
  | where EventOriginalType == "PowerAppPermissionEdited"
  | extend Properties = tostring(PropertyCollection)
  | extend AppId = extract(@'"powerplatform.analytics.resource.power_app.id","Value":"([^"]+)"', 1, Properties)
  | extend AppId = tolower(replace_string(AppId, '/providers/Microsoft.PowerApps/apps/', ''))
  | extend TargetPrincipalId = extract(@'"targetuser.id","Value":"([^"]+)"', 1, Properties)
  | join kind=leftouter (
      AuditLogs
      | where ActivityDateTime >= ago(query_lookback)
      | where SourceSystem =~ "Azure AD" and OperationName == "Invite external user"
      | where Result =~ "success"
      | extend InvitedOrgEmail = tostring(parse_json(AdditionalDetails[5])['value'])
      | extend InvitedOrgDomain = tostring(split(InvitedOrgEmail, "@")[1])
      | where not(InvitedOrgDomain has_any(allowed_domains))
      | extend
          InvitedById = tostring(parse_json(InitiatedBy)['user']['id']),
          InvitedByUPN = tostring(parse_json(InitiatedBy)['user']['userPrincipalName']),
          InvitedEmail = tostring(parse_json(TargetResources[0])['userPrincipalName']),
          InvitedId = tostring(parse_json(TargetResources[0])['id'])
      | summarize by InvitedById, InvitedByUPN, InvitedEmail, InvitedId, InvitedOrgDomain)
      on $left.TargetPrincipalId == $right.InvitedId
  | where isnotempty(InvitedId)
  | summarize
      StartTime = min(TimeGenerated),
      EndTime = max(TimeGenerated),
      TargetedUsersCount=dcount(TargetPrincipalId),
      TargetedObjectIds = make_set(TargetPrincipalId, 1000),
      InvitedDomains = make_set(InvitedOrgDomain, 1000),
      InvitedEmailAddresses = make_set(InvitedEmail, 1000)
      by AppId, InvitedById, InvitedByUPN
  | extend
      PowerAppsEntityId = 27593,
      AccountName = tostring(split(InvitedByUPN, '@')[0]),
      UPNSuffix = tostring(split(InvitedByUPN, '@')[1])
  | project
      StartTime,
      EndTime,
      InvitedByUPN,
      InvitedById,
      InvitedDomains,
      InvitedEmailAddresses,
      TargetedUsersCount,
      TargetedObjectIds,
      AppId,
      PowerAppsEntityId,
      AccountName,
      UPNSuffix
eventGroupingSettings:
  aggregationKind: SingleAlert
entityMappings:
  - entityType: Account
    fieldMappings:
      - identifier: Name
        columnName: AccountName
      - identifier: UPNSuffix
        columnName: UPNSuffix
  - entityType: CloudApplication
    fieldMappings:
      - identifier: AppId
        columnName: PowerAppsEntityId
      - identifier: InstanceName
        columnName: AppId
alertDetailsOverride:
  alertDisplayNameFormat: Power Apps - app shared with recently created external guest
    accounts
  alertDescriptionFormat: '{{InvitedByUPN}}  shared an app with {{TargetedUsersCount}}
    recently added guest user accounts that are not on the list of allowed partner
    domains. List of domain s {{InvitedDomains}}'
customDetails:
  PowerAppsApp: AppId
version: 3.2.0

Stages and Predicates

Parameters

let threshold = 5;
let allowed_domains = pack_array("contoso.com");
let query_frequency = 1h;
let query_lookback = 14d;

Stage 1: `source`

PowerPlatformAdminActivity

Stage 2: `where`

| where TimeGenerated >= ago(query_frequency)

Stage 3: `where`

| where EventOriginalType == "PowerAppPermissionEdited"

Stage 4: `extend` (4 consecutive steps)

| extend Properties = tostring(PropertyCollection)
| extend AppId = extract(@'"powerplatform.analytics.resource.power_app.id","Value":"([^"]+)"', 1, Properties)
| extend AppId = tolower(replace_string(AppId, '/providers/Microsoft.PowerApps/apps/', ''))
| extend TargetPrincipalId = extract(@'"targetuser.id","Value":"([^"]+)"', 1, Properties)

Stage 5: `join`

| join kind=leftouter (
    AuditLogs
    | where ActivityDateTime >= ago(query_lookback)
    | where SourceSystem =~ "Azure AD" and OperationName == "Invite external user"
    | where Result =~ "success"
    | extend InvitedOrgEmail = tostring(parse_json(AdditionalDetails[5])['value'])
    | extend InvitedOrgDomain = tostring(split(InvitedOrgEmail, "@")[1])
    | where not(InvitedOrgDomain has_any(allowed_domains))
    | extend
        InvitedById = tostring(parse_json(InitiatedBy)['user']['id']),
        InvitedByUPN = tostring(parse_json(InitiatedBy)['user']['userPrincipalName']),
        InvitedEmail = tostring(parse_json(TargetResources[0])['userPrincipalName']),
        InvitedId = tostring(parse_json(TargetResources[0])['id'])
    | summarize by InvitedById, InvitedByUPN, InvitedEmail, InvitedId, InvitedOrgDomain)
    on $left.TargetPrincipalId == $right.InvitedId

Stage 6: `where`

| where isnotempty(InvitedId)

Stage 7: `summarize`

| summarize
    StartTime = min(TimeGenerated),
    EndTime = max(TimeGenerated),
    TargetedUsersCount=dcount(TargetPrincipalId),
    TargetedObjectIds = make_set(TargetPrincipalId, 1000),
    InvitedDomains = make_set(InvitedOrgDomain, 1000),
    InvitedEmailAddresses = make_set(InvitedEmail, 1000)
    by AppId, InvitedById, InvitedByUPN

Stage 8: `extend`

| extend
    PowerAppsEntityId = 27593,
    AccountName = tostring(split(InvitedByUPN, '@')[0]),
    UPNSuffix = tostring(split(InvitedByUPN, '@')[1])

Stage 9: `project`

| project
    StartTime,
    EndTime,
    InvitedByUPN,
    InvitedById,
    InvitedDomains,
    InvitedEmailAddresses,
    TargetedUsersCount,
    TargetedObjectIds,
    AppId,
    PowerAppsEntityId,
    AccountName,
    UPNSuffix

Exclusions

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

Field	Kind	Excluded values
`InvitedOrgDomain`	match	`allowed_domains`

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
`EventOriginalType`	eq	`PowerAppPermissionEdited` transforms: `cased`
`InvitedId`	is_not_null	(no value, null check)
`OperationName`	eq	`Invite external user` transforms: `cased`
`Result`	eq	`success`
`SourceSystem`	eq	`Azure AD`

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
`AccountName`	`project`
`AppId`	`project`
`EndTime`	`project`
`InvitedById`	`project`
`InvitedByUPN`	`project`
`InvitedDomains`	`project`
`InvitedEmailAddresses`	`project`
`PowerAppsEntityId`	`project`
`StartTime`	`project`
`TargetedObjectIds`	`project`
`TargetedUsersCount`	`project`
`UPNSuffix`	`project`

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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)

Power Apps - Bulk sharing of Power Apps to newly created guest users

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend` (4 consecutive steps)

Stage 5: `join`

Stage 6: `where`

Stage 7: `summarize`

Stage 8: `extend`

Stage 9: `project`

Exclusions

Indicators

Output fields

Keyboard shortcuts

Search operators

Power Apps - Bulk sharing of Power Apps to newly created guest users

MITRE ATT&CK coverage

Event coverage

Rule body kusto

Stages and Predicates

Parameters

Stage 1: source

Stage 2: where

Stage 3: where

Stage 4: extend (4 consecutive steps)

Stage 5: join

Stage 6: where

Stage 7: summarize

Stage 8: extend

Stage 9: project

Exclusions

Indicators

Output fields

Stage 1: `source`

Stage 2: `where`

Stage 3: `where`

Stage 4: `extend` (4 consecutive steps)

Stage 5: `join`

Stage 6: `where`

Stage 7: `summarize`

Stage 8: `extend`

Stage 9: `project`