Check for Publicly Accessible Cloud Storage Buckets

ID: gcloud-publicly-accessible-storage-buckets

Severity: high

Author: princechaddha

Tags: cloud,devops,gcp,gcloud,google-cloud-storage,iam,security,public-access,gcp-cloud-config

Description

Ensure that the IAM policy associated with your Google Cloud Storage buckets is restricting anonymous and/or public access. The IAM policy should not include bindings for “allUsers” or “allAuthenticatedUsers” to prevent unauthorized access to sensitive data.

YAML Source

id: gcloud-publicly-accessible-storage-buckets

info:
  name: Check for Publicly Accessible Cloud Storage Buckets
  author: princechaddha
  severity: high
  description: |
    Ensure that the IAM policy associated with your Google Cloud Storage buckets is restricting anonymous and/or public access. The IAM policy should not include bindings for "allUsers" or "allAuthenticatedUsers" to prevent unauthorized access to sensitive data.
  impact: |
    Publicly accessible Cloud Storage buckets can lead to unauthorized access and potential data breaches, exposing sensitive information to the Internet.
  remediation: |
    Update the IAM policy of your Google Cloud Storage buckets to remove bindings for "allUsers" and "allAuthenticatedUsers" members, restricting access to authorized users only.
  reference:
    - https://cloud.google.com/storage/docs/access-control/iam
  tags: cloud,devops,gcp,gcloud,google-cloud-storage,iam,security,public-access,gcp-cloud-config

flow: |
  code(1)
  for(let projectId of iterate(template.projectIds)){
    set("projectId", projectId)
    code(2)
    for(let bucketName of iterate(template.buckets)){
      set("bucketName", bucketName)
      code(3)
    }
  }

self-contained: true

code:
  - engine:
      - sh
      - bash
    source: |
      gcloud projects list --format="json(projectId)"

    extractors:
      - type: json
        name: projectIds
        internal: true
        json:
          - '.[].projectId'

  - engine:
      - sh
      - bash
    source: |
      gsutil ls -p $projectId | jq -R . | jq -s .

    extractors:
      - type: json
        name: buckets
        internal: true
        json:
          - '.[]'

  - engine:
      - sh
      - bash
    source: |
      gsutil iam get $bucketName --format=json | jq -r '.bindings[].members[]? // "null"'

    matchers:
      - type: word
        words:
          - 'allUsers'
          - 'allAuthenticatedUsers'
        condition: or

    extractors:
      - type: dsl
        dsl:
          - '"The bucket " + bucketName + " in project " + projectId + " is publicly accessible because it includes \"allUsers\" or \"allAuthenticatedUsers\" in its IAM policy."'
# digest: 4a0a00473045022100ca343efb1fdb4637265347cdbfe3addcca0e190c2380f1bd0036f03a5c92f44302205d1f5bf2a77c7c47f0c885372be462ab5016675157d11cc7668801b97d740778:922c64590222798bb761d5b6d8e72950

Guide to check the vulnerabilities

This template is used to detect vulnerabilities in web applications. It can be used with the Nuclei tool to scan for specific patterns or behaviors.

$ nuclei -u "URL" -t "cloud/gcp/storage/gcloud-publicly-accessible-storage-buckets.yaml"

View on Github