Performing GCP Penetration Testing with GCPBucketBrute

Overview

This guide covers Google Cloud Platform security testing using GCPBucketBrute for storage bucket enumeration and access permission testing, combined with gcloud CLI IAM enumeration to identify privilege escalation paths. The approach tests for publicly accessible buckets, overly permissive IAM bindings, and service account key exposure.

Prerequisites

• Python 3.8+ with google-cloud-storage library
• GCPBucketBrute installed from RhinoSecurityLabs GitHub
• gcloud CLI authenticated with test credentials
• Authorized penetration testing scope for target GCP project
• google-api-python-client and google-auth libraries

Steps

1. Enumerate Storage Buckets — Use GCPBucketBrute with keyword permutations to discover accessible GCP storage buckets
2. Test Bucket Permissions — Call TestIamPermissions API on each discovered bucket to determine read/write/admin access levels
3. Audit IAM Bindings — Enumerate project-level IAM policies to identify overly permissive role bindings
4. Check Service Account Keys — Identify service accounts with user-managed keys and test for privilege escalation via impersonation
5. Test Privilege Escalation Paths — Check for iam.serviceAccounts.actAs, setIamPolicy, and other privilege escalation vectors
6. Generate Findings Report — Produce a structured security assessment with risk severity ratings

Expected Output

• JSON report of discovered buckets with permission levels
• IAM privilege escalation path analysis
• Service account security assessment
• Risk-scored findings with remediation recommendations

Verification Criteria

Confirm successful execution by validating:

• [ ] All prerequisite tools and access requirements are satisfied
• [ ] Each workflow step completed without errors
• [ ] Output matches expected format and contains expected data
• [ ] No security warnings or misconfigurations detected
• [ ] Results are documented and evidence is preserved for audit

Compliance Framework Mapping

This skill supports compliance evidence collection across multiple frameworks:

• SOC 2: CC6.1 (Logical Access), CC6.6 (System Boundaries), CC7.1 (Monitoring)
• ISO 27001: A.8.1 (Asset Management), A.13.1 (Network Security), A.14.1 (System Acquisition)
• NIST 800-53: AC-3 (Access Enforcement), SC-7 (Boundary Protection), CM-7 (Least Functionality)
• NIST CSF: PR.AC (Access Control), PR.DS (Data Security), DE.CM (Continuous Monitoring)

Claw GRC Tip: When this skill is executed by a registered agent, compliance evidence is automatically captured and mapped to the relevant controls in your active frameworks.

Deploying This Skill with Claw GRC

Agent Execution

Register this skill with your Claw GRC agent for automated execution:

# Install via CLI
npx claw-grc skills add performing-gcp-penetration-testing-with-gcpbucketbrute

# Or load dynamically via MCP
grc.load_skill("performing-gcp-penetration-testing-with-gcpbucketbrute")

Audit Trail Integration

When executed through Claw GRC, every step of this skill generates tamper-evident audit records:

• SHA-256 chain hashing ensures no step can be modified after execution
• Evidence artifacts (configs, scan results, logs) are automatically attached to relevant controls
• Trust score impact — successful execution increases your agent's trust score

Continuous Compliance

Schedule this skill for recurring execution to maintain continuous compliance posture. Claw GRC monitors for drift and alerts when re-execution is needed.