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Detection rules › Sigma

Google Cloud Storage Buckets Enumeration

Status
test
Severity
low
Log source
product gcp, service gcp.audit
Author
Austin Songer @austinsonger
Source
github.com/SigmaHQ/sigma

Detects when storage bucket is enumerated in Google Cloud.

Known false positives

  • Storage Buckets being enumerated may be performed by a system administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
  • Storage Buckets enumerated from unfamiliar users should be investigated. If known behavior is causing false positives, it can be exempted from the rule.

MITRE ATT&CK coverage

TacticTechniques
DiscoveryNo specific technique

Telemetry coverage

PlatformRecord / event type
GCPstorage.buckets.list: List buckets
GCPstorage.buckets.listChannels: List bucket notification channels

Rule body

title: Google Cloud Storage Buckets Enumeration
id: e2feb918-4e77-4608-9697-990a1aaf74c3
status: test
description: Detects when storage bucket is enumerated in Google Cloud.
references:
    - https://cloud.google.com/storage/docs/json_api/v1/buckets
author: Austin Songer @austinsonger
date: 2021-08-14
modified: 2022-10-09
tags:
    - attack.discovery
logsource:
    product: gcp
    service: gcp.audit
detection:
    selection:
        gcp.audit.method_name:
            - storage.buckets.list
            - storage.buckets.listChannels
    condition: selection
falsepositives:
    - Storage Buckets being enumerated may be performed by a system administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
    - Storage Buckets enumerated from unfamiliar users should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
level: low

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    gcp.audit.method_name:
        - storage.buckets.list
        - storage.buckets.listChannels

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
gcp.audit.method_nameeq
  • storage.buckets.list
  • storage.buckets.listChannels
field:"gcp::method_name" kind:eq