Azure Invite External Users

Severity: low
Log types: Azure.Audit
Reference: https://learn.microsoft.com/en-us/entra/identity/authentication/overview-authentication
Source: github.com/panther-labs/panther-analysis

This detection looks for a Azure users inviting external users

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1078` Valid Accounts

Rule body yaml

AnalysisType: rule
Filename: azure_invite_external_users.py
RuleID: "Azure.Audit.InviteExternalUsers"
DisplayName: "Azure Invite External Users"
Enabled: true
LogTypes:
  - Azure.Audit
Severity: Low
Description: >
  This detection looks for a Azure users inviting external users
Reports:
  MITRE ATT&CK:
    - TA0001:T1078
Runbook: >
  Verify the user permissions and investigate the external user details. If unauthorized, revoke access and block further invites. Update security policies.

Reference: https://learn.microsoft.com/en-us/entra/identity/authentication/overview-authentication
SummaryAttributes:
  - properties:ServicePrincipalName
  - properties:UserPrincipalName
  - properties:initiatedBy:user:ipAddress
Tests:
  - Name: Successful Invite external user
    ExpectedResult: true
    Log:
      {
        "callerIpAddress": "1.1.1.1",
        "category": "AuditLogs",
        "correlationId": "123456789",
        "durationMs": 0,
        "Level": "4",
        "operationName": "Invite external user",
        "operationVersion": "1.0",
        "properties": {
          "activityDateTime": "2024-09-23 14:33:09.049661100",
          "activityDisplayName": "Invite external user",
          "additionalDetails": [
            {
              "key": "oid",
              "value": "123456789"
            },
            {
              "key": "tid",
              "value": "0123456789"
            },
            {
              "key": "ipaddr",
              "value": "1.2.3.4"
            },
            {
              "key": "wids",
              "value": "123456789"
            },
            {
              "key": "InvitationId",
              "value": "123456789"
            },
            {
              "key": "invitedUserEmailAddress",
              "value": "john@justice.org"
            }
          ],
          "category": "UserManagement",
          "correlationId": "123456789",
          "id": "Invited Users_123456789",
          "initiatedBy": {
            "user": {
              "id": "123456789",
              "ipAddress": "1.2.3.4",
              "roles": [],
              "userPrincipalName": "denethor@lotr.com"
            }
          },
          "loggedByService": "Invited Users",
          "operationType": "Add",
          "result": "success",
          "targetResources": [
            {
              "administrativeUnits": [],
              "displayName": "Zeus.Theboss",
              "id": "123456789",
              "type": "User"
            }
          ]
        },
        "resourceId": "/tenants/123456789/providers/Microsoft.aadiam",
        "resultSignature": "None",
        "tenantId": "123456789",
        "time": "2024-12-10 14:33:09.049661100"
      }
  - Name: Same org successful invite    
    ExpectedResult: false
    Log:
      {
        "callerIpAddress": "1.1.1.1",
        "category": "AuditLogs",
        "correlationId": "123456789",
        "durationMs": 0,
        "Level": "4",
        "operationName": "Invite external user",
        "operationVersion": "1.0",
        "properties": {
          "activityDateTime": "2024-09-23 14:33:09.049661100",
          "activityDisplayName": "Invite external user",
          "additionalDetails": [
            {
              "key": "oid",
              "value": "123456789"
            },
            {
              "key": "tid",
              "value": "0123456789"
            },
            {
              "key": "ipaddr",
              "value": "1.2.3.4"
            },
            {
              "key": "wids",
              "value": "123456789"
            },
            {
              "key": "InvitationId",
              "value": "123456789"
            },
            {
              "key": "invitedUserEmailAddress",
              "value": "aragorn@lotr.com"
            }
          ],
          "category": "UserManagement",
          "correlationId": "123456789",
          "id": "Invited Users_123456789",
          "initiatedBy": {
            "user": {
              "id": "123456789",
              "ipAddress": "1.2.3.4",
              "roles": [],
              "userPrincipalName": "denethor@lotr.com"
            }
          },
          "loggedByService": "Invited Users",
          "operationType": "Add",
          "result": "success",
          "targetResources": [
            {
              "administrativeUnits": [],
              "displayName": "Zeus.Theboss",
              "id": "123456789",
              "type": "User"
            }
          ]
        },
        "resourceId": "/tenants/123456789/providers/Microsoft.aadiam",
        "resultSignature": "None",
        "tenantId": "123456789",
        "time": "2024-12-10 14:33:09.049661100"
      }
  - Name: Unsuccessful invite    
    ExpectedResult: false
    Log:
      {
        "callerIpAddress": "1.1.1.1",
        "category": "AuditLogs",
        "correlationId": "123456789",
        "durationMs": 0,
        "Level": "4",
        "operationName": "Invite external user",
        "operationVersion": "1.0",
        "properties": {
          "activityDateTime": "2024-09-23 14:33:09.049661100",
          "activityDisplayName": "Invite external user",
          "additionalDetails": [
            {
              "key": "oid",
              "value": "123456789"
            },
            {
              "key": "tid",
              "value": "0123456789"
            },
            {
              "key": "ipaddr",
              "value": "1.2.3.4"
            },
            {
              "key": "wids",
              "value": "123456789"
            },
            {
              "key": "InvitationId",
              "value": "123456789"
            },
            {
              "key": "invitedUserEmailAddress",
              "value": "aragorn@lotr.com"
            }
          ],
          "category": "UserManagement",
          "correlationId": "123456789",
          "id": "Invited Users_123456789",
          "initiatedBy": {
            "user": {
              "id": "123456789",
              "ipAddress": "1.2.3.4",
              "roles": [],
              "userPrincipalName": "denethor@lotr.com"
            }
          },
          "loggedByService": "Invited Users",
          "operationType": "Add",
          "result": "failed",
          "targetResources": [
            {
              "administrativeUnits": [],
              "displayName": "Zeus.Theboss",
              "id": "123456789",
              "type": "User"
            }
          ]
        },
        "resourceId": "/tenants/123456789/providers/Microsoft.aadiam",
        "resultSignature": "None",
        "tenantId": "123456789",
        "time": "2024-12-10 14:33:09.049661100"
      }
  - Name: Not external invite  
    ExpectedResult: false
    Log:
      {
        "callerIpAddress": "1.1.1.1",
        "category": "AuditLogs",
        "correlationId": "123456789",
        "durationMs": 0,
        "Level": "4",
        "operationName": "Invite Internal User",
        "operationVersion": "1.0",
        "properties": {
          "activityDateTime": "2024-09-23 14:33:09.049661100",
          "activityDisplayName": "Invite external user",
          "additionalDetails": [
            {
              "key": "oid",
              "value": "123456789"
            },
            {
              "key": "tid",
              "value": "0123456789"
            },
            {
              "key": "ipaddr",
              "value": "1.2.3.4"
            },
            {
              "key": "wids",
              "value": "123456789"
            },
            {
              "key": "InvitationId",
              "value": "123456789"
            },
            {
              "key": "invitedUserEmailAddress",
              "value": "Kratos@mtolympus.com"
            }
          ],
          "category": "UserManagement",
          "correlationId": "123456789",
          "id": "Invited Users_123456789",
          "initiatedBy": {
            "user": {
              "id": "123456789",
              "ipAddress": "1.2.3.4",
              "roles": [],
              "userPrincipalName": "Zeus@mtolympus.com"
            }
          },
          "loggedByService": "Invited Users",
          "operationType": "Add",
          "result": "success",
          "targetResources": [
            {
              "administrativeUnits": [],
              "displayName": "Zeus.Theboss",
              "id": "123456789",
              "type": "User"
            }
          ]
        },
        "resourceId": "/tenants/123456789/providers/Microsoft.aadiam",
        "resultSignature": "None",
        "tenantId": "123456789",
        "time": "2024-12-10 14:33:09.049661100"
      }

Detection logic

Condition

not (properties.result ne "success" or operationName ne "Invite external user")

This rule also runs imperative logic the parser cannot express as a filter; the conditions above are the structured part it could extract.

Exclusions

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

Field	Kind	Excluded values
`operationName`	ne	`Invite external user`
`properties.result`	ne	`success`

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
`operationName`
`category`	`properties.category`
`actor_id`	`properties.initiatedBy.user.id`
`actor_upn`	`properties.initiatedBy.user.userPrincipalName`
`source_ip_address`	`properties.initiatedBy.user.ipAddress`
`target_id`	`properties.targetResources.id`
`target_name`	`properties.targetResources.displayName`
`value`	`properties.additionalDetails.value`

`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)