GCP Privilege Escalation via TagBinding

Severity: informational
Time window: 15m
Match by: p_alert_context.principal
Tags: attack.privilege_escalation, attack.t1548, gcp, iam, tagbinding, Beta
Reference: https://cloud.google.com/resource-manager/docs/tags/tags-overview
Source: github.com/panther-labs/panther-analysis

Detects a sequence of events that could indicate a privilege escalation attempt via GCP's tag-based access control. The sequence includes: 1. Enumeration of IAM policies and tags 2. Creation of a tag binding 3. Performance of a privileged operation

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1548` Abuse Elevation Control Mechanism

Rule body yaml

AnalysisType: correlation_rule
RuleID: "GCP.Privilege.Escalation.Via.TagBinding"
DisplayName: "GCP Privilege Escalation via TagBinding"
Enabled: true
Severity: Info
Description: >
  Detects a sequence of events that could indicate a privilege escalation attempt
  via GCP's tag-based access control. The sequence includes:
  1. Enumeration of IAM policies and tags
  2. Creation of a tag binding
  3. Performance of a privileged operation
Reference: https://cloud.google.com/resource-manager/docs/tags/tags-overview
Runbook: >
  Verify if the user has legitimate business need for this sequence of operations.
  If unauthorized, revoke the tag binding and review IAM policies.
Reports:
    MITRE ATT&CK:
        - TA0004:T1548  # Abuse Elevation Control Mechanism
Detection:
    - Sequence:
        - ID: Enumeration
          RuleID: GCP.IAM.Tag.Enumeration
        - ID: TagBinding
          RuleID: GCP.Tag.Binding.Creation
        - ID: PrivilegedOperation
          RuleID: GCP.Privileged.Operation
      Transitions:
        - ID: Enumeration FOLLOWED BY TagBinding
          From: Enumeration
          To: TagBinding
          WithinTimeFrameMinutes: 15
          Match:
            - On: p_alert_context.principal
        - ID: TagBinding FOLLOWED BY PrivilegedOperation
          From: TagBinding
          To: PrivilegedOperation
          WithinTimeFrameMinutes: 15
          Match:
            - On: p_alert_context.principal
      Schedule:
        RateMinutes: 1440
        TimeoutMinutes: 10
      LookbackWindowMinutes: 2160
Tags:
    - attack.privilege_escalation
    - attack.t1548
    - gcp
    - iam
    - tagbinding
    - Beta
Tests:
    - Name: Complete Attack Sequence
      ExpectedResult: true
      RuleOutputs:
        - ID: Enumeration
          Matches:
            p_alert_context.principal:
              "test@example.com":
                - "2024-06-01T10:00:00Z"
        - ID: TagBinding
          Matches:
            p_alert_context.principal:
              "test@example.com":
                - "2024-06-01T10:00:05Z"
        - ID: PrivilegedOperation
          Matches:
            p_alert_context.principal:
              "test@example.com":
                - "2024-06-01T10:00:10Z"

    - Name: Incomplete Sequence
      ExpectedResult: false
      RuleOutputs:
        - ID: Enumeration
          Matches:
            p_alert_context.principal:
              "test@example.com":
                - "2024-06-01T10:00:00Z"
        - ID: PrivilegedOperation
          Matches:
            p_alert_context.principal:
              "test@example.com":
                - "2024-06-01T10:00:10Z"

Detection logic

Stage 1: `step Enumeration` ordered before `$TagBinding`

References detection GCP.IAM.Tag.Enumeration.

Stage 2: `step TagBinding` ordered before `$PrivilegedOperation` ordered after `$Enumeration`

References detection GCP.Tag.Binding.Creation.

Stage 3: `step PrivilegedOperation` ordered after `$TagBinding`

References detection GCP.Privileged.Operation.

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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)

GCP Privilege Escalation via TagBinding

MITRE ATT&CK coverage

Rule body yaml

Detection logic

Stage 1: `step Enumeration` ordered before `$TagBinding`

Stage 2: `step TagBinding` ordered before `$PrivilegedOperation` ordered after `$Enumeration`

Stage 3: `step PrivilegedOperation` ordered after `$TagBinding`

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GCP Privilege Escalation via TagBinding

MITRE ATT&CK coverage

Rule body yaml

Detection logic

Stage 1: step Enumeration ordered before $TagBinding

Stage 2: step TagBinding ordered before $PrivilegedOperation ordered after $Enumeration

Stage 3: step PrivilegedOperation ordered after $TagBinding

Stage 1: `step Enumeration` ordered before `$TagBinding`

Stage 2: `step TagBinding` ordered before `$PrivilegedOperation` ordered after `$Enumeration`

Stage 3: `step PrivilegedOperation` ordered after `$TagBinding`