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Detection rules › Panther

GSuite Calendar Has Been Made Public

Severity
medium
Log types
GSuite.ActivityEvent
Tags
GSuite
Reference
https://support.google.com/calendar/answer/37083?hl=en&sjid=864417124752637253-EU
Source
github.com/panther-labs/panther-analysis

A User or Admin Has Modified A Calendar To Be Public

MITRE ATT&CK coverage

TacticTechniques
DiscoveryT1087 Account Discovery

Rule body yaml

AnalysisType: rule
Filename: gsuite_calendar_made_public.py
RuleID: "GSuite.CalendarMadePublic"
DisplayName: "GSuite Calendar Has Been Made Public"
Enabled: true
LogTypes:
  - GSuite.ActivityEvent
Tags:
  - GSuite
Reports:
  MITRE ATT&CK:
    - TA0007:T1087
Severity: Medium
Description: >
  A User or Admin Has Modified A Calendar To Be Public
Reference: https://support.google.com/calendar/answer/37083?hl=en&sjid=864417124752637253-EU
Runbook: >
  Follow up with user about this calendar share.
SummaryAttributes:
  - actor:email
Tests:
  - Name: User Publically Shared a Calendar
    ExpectedResult: true
    Log:
      {
        "actor":
          { "email": "user@example.io", "profileId": "110111111111111111111" },
        "id":
          {
            "applicationName": "calendar",
            "customerId": "D12345",
            "time": "2022-12-10 22:33:31.852000000",
            "uniqueQualifier": "-2888888888888888888",
          },
        "ipAddress": "1.2.3.4",
        "kind": "admin#reports#activity",
        "name": "change_calendar_acls",
        "ownerDomain": "example.io",
        "parameters":
          {
            "access_level": "freebusy",
            "api_kind": "web",
            "calendar_id": "user@example.io",
            "grantee_email": "__public_principal__@public.calendar.google.com",
            "user_agent": "Mozilla/5.0",
          },
        "type": "calendar_change",
      }
  - Name: User Made Calendar Private
    ExpectedResult: true
    Log:
      {
        "actor":
          { "email": "user@example.io", "profileId": "110111111111111111111" },
        "id":
          {
            "applicationName": "calendar",
            "customerId": "D12345",
            "time": "2022-12-10 22:33:31.852000000",
            "uniqueQualifier": "-2888888888888888888",
          },
        "ipAddress": "1.2.3.4",
        "kind": "admin#reports#activity",
        "name": "change_calendar_acls",
        "ownerDomain": "example.io",
        "parameters":
          {
            "access_level": "none",
            "api_kind": "web",
            "calendar_id": "user@example.io",
            "grantee_email": "__public_principal__@public.calendar.google.com",
            "user_agent": "Mozilla/5.0",
          },
        "type": "calendar_change",
      }
  - Name: Admin Set Default Calendar SHARING_OUTSIDE_DOMAIN Setting to READ_WRITE_ACCESS
    ExpectedResult: false
    Log:
      {
        "actor":
          {
            "callerType": "USER",
            "email": "example@example.io",
            "profileId": "12345",
          },
        "id":
          {
            "applicationName": "admin",
            "customerId": "D12345",
            "time": "2022-12-11 01:06:26.303000000",
            "uniqueQualifier": "-12345",
          },
        "ipAddress": "12.12.12.12",
        "kind": "admin#reports#activity",
        "name": "CHANGE_CALENDAR_SETTING",
        "parameters":
          {
            "DOMAIN_NAME": "example.io",
            "NEW_VALUE": "READ_WRITE_ACCESS",
            "OLD_VALUE": "READ_ONLY_ACCESS",
            "ORG_UNIT_NAME": "Example IO",
            "SETTING_NAME": "SHARING_OUTSIDE_DOMAIN",
          },
        "type": "CALENDAR_SETTINGS",
      }
  - Name: ListObject Type
    ExpectedResult: false
    Log:
      {
        "actor":
          { "email": "user@example.io", "profileId": "118111111111111111111" },
        "id":
          {
            "applicationName": "drive",
            "customerId": "D12345",
            "time": "2022-12-20 17:27:47.080000000",
            "uniqueQualifier": "-7312729053723258069",
          },
        "ipAddress": "12.12.12.12",
        "kind": "admin#reports#activity",
        "name": "rename",
        "parameters":
          {
            "actor_is_collaborator_account": null,
            "billable": true,
            "doc_id": "1GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG",
            "doc_title": "Document Title- Found Here",
            "doc_type": "presentation",
            "is_encrypted": null,
            "new_value": ["Document Title- Found Here"],
            "old_value": ["Document Title- Old"],
            "owner": "user@example.io",
            "owner_is_shared_drive": null,
            "owner_is_team_drive": null,
            "primary_event": true,
            "visibility": "private",
          },
        "type": "access",
      }

Detection logic

Condition

name eq "change_calendar_acls"
parameters.grantee_email eq "__public_principal__@public.calendar.google.com"

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.

FieldKindValues
nameeq
  • change_calendar_acls
parameters.grantee_emaileq
  • __public_principal__@public.calendar.google.com

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.

FieldSource
calendar_idparameters.calendar_id
emailactor.email