External GSuite File Share

Severity: high
Log types: GSuite.ActivityEvent
Tags: GSuite, Security Control, Configuration Required, Collection:Data from Information Repositories
Reference: https://support.google.com/docs/answer/2494822?hl=en&co=GENIE.Platform%3DiOS&sjid=864417124752637253-EU
Source: github.com/panther-labs/panther-analysis

An employee shared a sensitive file externally with another organization

MITRE ATT&CK coverage

Tactic	Techniques
Collection	`T1213` Data from Information Repositories

Rule body yaml

AnalysisType: rule
Filename: gsuite_drive_external_share.py
RuleID: "GSuite.Drive.ExternalFileShare"
DisplayName: "External GSuite File Share"
Enabled: false
LogTypes:
  - GSuite.ActivityEvent
Tags:
  - GSuite
  - Security Control
  - Configuration Required
  - Collection:Data from Information Repositories
Reports:
  MITRE ATT&CK:
    - TA0009:T1213
Severity: High
Description: An employee shared a sensitive file externally with another organization
Runbook: |
  Contact the employee who made the share and make sure they redact the access.
  If the share was legitimate, add to the EXCEPTION_PATTERNS in the detection.
Reference: https://support.google.com/docs/answer/2494822?hl=en&co=GENIE.Platform%3DiOS&sjid=864417124752637253-EU
Tests:
  - Name: Dangerous Share of Known Document with a Missing User
    LogType: GSuite.ActivityEvent
    ExpectedResult: true
    Log:
      {
        "kind": "admin#reports#activity",
        "id":
          {
            "time": "2020-09-07T15:50:49.617Z",
            "uniqueQualifier": "1111111111111111111",
            "applicationName": "drive",
            "customerId": "C010qxghg",
          },
        "actor":
          { "email": "example@acme.com", "profileId": "1111111111111111111" },
        "type": "acl_change",
        "name": "change_user_access",
        "parameters":
          {
            "primary_event": true,
            "visibility_change": "external",
            "target_user": "outside@acme.com",
            "old_visibility": "private",
            "doc_id": "1111111111111111111",
            "doc_type": "document",
            "doc_title": "1 Document Title Primary",
            "visibility": "shared_externally",
            "originating_app_id": "1111111111111111111",
            "owner_is_shared_drive": false,
            "owner_is_team_drive": false,
            "old_value": ["none"],
            "new_value": ["can_edit"],
          },
        "p_log_type": "GSuite.ActivityEvent",
      }
  - Name: Dangerous Share of Unknown Document
    LogType: GSuite.ActivityEvent
    ExpectedResult: true
    Log:
      {
        "kind": "admin#reports#activity",
        "id":
          {
            "time": "2020-09-07T15:50:49.617Z",
            "uniqueQualifier": "1111111111111111111",
            "applicationName": "drive",
            "customerId": "C010qxghg",
          },
        "actor":
          { "email": "example@acme.com", "profileId": "1111111111111111111" },
        "type": "acl_change",
        "name": "change_user_access",
        "parameters":
          {
            "primary_event": true,
            "visibility_change": "external",
            "target_domain": "external.com",
            "old_visibility": "private",
            "doc_id": "1111111111111111111",
            "doc_type": "document",
            "doc_title": "Untitled document",
            "visibility": "shared_externally",
            "originating_app_id": "1111111111111111111",
            "owner_is_shared_drive": false,
            "owner_is_team_drive": false,
            "old_value": ["none"],
            "new_value": ["can_edit"],
          },
        "p_log_type": "GSuite.ActivityEvent",
      }
  - Name: Share Allowed by Exception
    LogType: GSuite.ActivityEvent
    ExpectedResult: false
    Log:
      {
        "kind": "admin#reports#activity",
        "id":
          {
            "time": "2020-07-07T15:50:49.617Z",
            "uniqueQualifier": "1111111111111111111",
            "applicationName": "drive",
            "customerId": "C010qxghg",
          },
        "actor":
          { "email": "alice@acme.com", "profileId": "1111111111111111111" },
        "type": "acl_change",
        "name": "change_user_access",
        "parameters":
          {
            "primary_event": true,
            "billable": true,
            "visibility_change": "external",
            "target_user": "samuel@abc.com",
            "old_visibility": "private",
            "doc_id": "1111111111111111111",
            "doc_type": "document",
            "doc_title": "1 Document Title Pattern",
            "visibility": "shared_externally",
            "originating_app_id": "1111111111111111111",
            "owner_is_shared_drive": false,
            "owner_is_team_drive": false,
            "old_value": ["none"],
            "new_value": ["people_within_domain_with_link"],
          },
        "p_log_type": "GSuite.ActivityEvent",
      }
  - Name: Share Allowed by Exception - 2
    LogType: GSuite.ActivityEvent
    ExpectedResult: false
    Log:
      {
        "kind": "admin#reports#activity",
        "id":
          {
            "time": "2020-07-07T15:50:49.617Z",
            "uniqueQualifier": "1111111111111111111",
            "applicationName": "drive",
            "customerId": "C010qxghg",
          },
        "actor":
          { "email": "alice@abc.com", "profileId": "1111111111111111111" },
        "type": "acl_change",
        "name": "change_user_access",
        "parameters":
          {
            "primary_event": true,
            "billable": true,
            "visibility_change": "external",
            "target_user": "samuel@acme.com",
            "old_visibility": "private",
            "doc_id": "1111111111111111111",
            "doc_type": "document",
            "doc_title": "2 Document Title Pattern",
            "visibility": "shared_externally",
            "originating_app_id": "1111111111111111111",
            "owner_is_shared_drive": false,
            "owner_is_team_drive": false,
            "old_value": ["none"],
            "new_value": ["people_within_domain_with_link"],
          },
        "p_log_type": "GSuite.ActivityEvent",
      }

Detection logic

Condition

id.applicationName eq "drive"
type eq "acl_change"
parameters.visibility eq "shared_externally"
parameters.old_visibility eq "private"

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

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
`id.applicationName`	eq	`drive`
`parameters.old_visibility`	eq	`private`
`parameters.visibility`	eq	`shared_externally`
`type`	eq	`acl_change`

`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)