Gsuite Email Bypassed Spam Filter

Severity: medium
Entities: actor_ids, domain_names, ip_addresses
Log types: GSuite.ActivityEvent
Tags: GSuite
Source: github.com/panther-labs/panther-analysis

Detects if an email received by a user has bypassed the organization's spam filter.

MITRE ATT&CK coverage

Tactic	Techniques
Initial Access	`T1566` Phishing

Rule body yaml

AnalysisType: rule
Filename: gsuite_bypass_spam_filter_email.py
RuleID: "GSuite.Gmail.Email.SpamFilter.Bypass"
DisplayName: "Gsuite Email Bypassed Spam Filter"
Enabled: true
LogTypes:
  - GSuite.ActivityEvent
Tags:
  - GSuite
Reports:
  MITRE ATT&CK:
    - TA0001:T1566 # Initial Access: Phishing
Severity: Medium
Description: >
  Detects if an email received by a user has bypassed the organization's spam filter.
Threshold: 1
DedupPeriodMinutes: 60
Tests:
  - Name: Spam Bypass Email
    ExpectedResult: true
    Log:
      {
        "p_any_ip_addresses": [
          "1.1.1.1"
        ],
        "p_any_actor_ids": [
          "1234567891234"
        ],
        "p_any_domain_names": [
          "evil.com"
        ],
        "p_event_time": "2025-11-04 20:44:43.248000000",
        "p_log_type": "GSuite.ActivityEvent",
        "p_parse_time": "2025-11-04 20:49:46.688935963",
        "p_row_id": "0000000000de09c1dc6f0828cbad2ca5",
        "p_schema_version": 0,
        "p_source_id": "7ee69d4d-df1b-40b3-b5e8-6826dee34b1c",
        "p_source_label": "Google Workspace",
        "p_udm": {
          "source": {
            "address": "1.1.1.1",
            "ip": "1.1.1.1"
          },
          "user": {
            "provider_id": "123456789"
          }
        },
        "actor": {
          "callerType": "USER",
          "email": "denethor@lotr.com",
          "profileId": "123456789"
        },
        "id": {
          "applicationName": "gmail",
          "customerId": "1A2B3C",
          "time": "2025-11-04 20:44:43.248000000",
          "uniqueQualifier": "-123456789"
        },
        "ipAddress": "1.1.1.1",
        "kind": "admin#reports#activity",
        "name": "delivery",
        "parameters": {
          "event_info": {
            "elapsed_time_usec": 368746,
            "timestamp_usec": 1762289083248347
          },
          "message_info": {
            "action_type": 19,
            "flattened_destinations": "gmail-for-work-catchall::denethor@lotr.com",
            "link_domain": [
              "evil.com"
            ],
            "payload_size": 12345,
            "subject": "You won 1 Million Dollar",
            "message_set": {
            "type": 46}
          },
        },
        "type": "delivery_type"
      }
  - Name: Other Email Event
    ExpectedResult: false
    Log:
       {
        "p_any_ip_addresses": [
          "1.1.1.1"
        ],
        "p_any_actor_ids": [
          "1234567891234"
        ],
        "p_any_domain_names": [
          "evil.com"
        ],
        "p_event_time": "2025-11-04 20:44:43.248000000",
        "p_log_type": "GSuite.ActivityEvent",
        "p_parse_time": "2025-11-04 20:49:46.688935963",
        "p_row_id": "165c80e3df1fc1cb9fb49af829c4fe26",
        "p_schema_version": 0,
        "p_source_id": "7ee69d4d-df1b-40b3-b5e8-6826dee34b1c",
        "p_source_label": "Google Workspace",
        "p_udm": {
          "source": {
            "address": "1.1.1.1",
            "ip": "1.1.1.1"
          },
          "user": {
            "provider_id": "123456789"
          }
        },
        "actor": {
          "callerType": "USER",
          "email": "aragorn@lotr.com",
          "profileId": "123456789"
        },
        "id": {
          "applicationName": "gmail",
          "customerId": "1A2B3C",
          "time": "2025-11-04 20:44:43.248000000",
          "uniqueQualifier": "-123456789"
        },
        "ipAddress": "1.1.1.1",
        "kind": "admin#reports#activity",
        "name": "delivery",
        "parameters": {
          "event_info": {
            "elapsed_time_usec": 368746,
            "timestamp_usec": 1762289083248347
          },
          "message_info": {
            "action_type": 19,
            "flattened_destinations": "gmail-for-work-catchall::aragorn@lotr.com",
            "link_domain": [
              "evil.com"
            ],
            "payload_size": 12345,
            "subject": "You won 1 Million Dollar",
            "message_set": {
            "type": 1}
          },
        },
        "type": "delivery_type"
      }

Detection logic

Condition

id.applicationName eq "gmail"
parameters.message_info.message_set.type eq "46"

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	`gmail`
`parameters.message_info.message_set.type`	eq	`46`

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
`actor`	`actor.email`
`applicationName`	`id.applicationName`
`name`
`type`
`parameters`
`subject`	`parameters.message_info.subject`

`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)