| name | performing-gcp-security-assessment-with-forseti |
| description | 'Performing comprehensive security assessments of Google Cloud Platform environments using Forseti Security, Security Command Center, and gcloud CLI to audit IAM policies, firewall rules, storage permissions, and compliance against CIS GCP Foundations Benchmark. ' |
| domain | cybersecurity |
| subdomain | cloud-security |
| tags | - cloud-security - gcp - forseti - security-command-center - iam-audit - cis-benchmark |
| version | '1.0' |
| author | mahipal |
| license | Apache-2.0 |
| nist_ai_rmf | - MEASURE-2.7 - MAP-5.1 - MANAGE-2.4 - GOVERN-1.1 - GOVERN-4.2 |
| atlas_techniques | - AML.T0070 - AML.T0066 - AML.T0082 |
| nist_csf | - PR.IR-01 - ID.AM-08 - GV.SC-06 - DE.CM-01 |
Performing GCP Security Assessment with Forseti
When to Use
- When conducting periodic security assessments of GCP organizations and projects
- When onboarding new GCP projects and establishing security baselines
- When compliance mandates CIS GCP Foundations Benchmark evaluation
- When auditing IAM bindings, firewall rules, and storage ACLs across multiple GCP projects
- When building continuous security monitoring for GCP infrastructure
Do not use as a replacement for GCP Security Command Center Premium for real-time threat detection, for application-level vulnerability scanning (use Web Security Scanner), or for GKE-specific security (use GKE Security Posture).
Prerequisites
- GCP Organization with Organization Admin or Security Admin IAM role
- gcloud CLI authenticated with sufficient permissions (
roles/securitycenter.admin, roles/iam.securityReviewer)
- Security Command Center (SCC) enabled at the organization level
- ScoutSuite installed for multi-cloud comparison (
pip install scoutsuite)
- Python 3.8+ for custom audit scripts using google-cloud-asset and google-cloud-securitycenter libraries
Workflow
Step 1: Enable Security Command Center and Asset Inventory
Enable SCC and set up Cloud Asset Inventory for comprehensive resource visibility.
gcloud services enable securitycenter.googleapis.com \
--project=PROJECT_ID
gcloud services enable cloudasset.googleapis.com \
--project=PROJECT_ID
gcloud asset search-all-resources \
--scope=organizations/ORG_ID \
--asset-types="compute.googleapis.com/Instance,storage.googleapis.com/Bucket,iam.googleapis.com/ServiceAccount" \
--format="table(name, assetType, location, project)"
gcloud asset export \
--organization=ORG_ID \
--output-bigquery-force \
--output-bigquery-dataset=projects/PROJECT_ID/datasets/asset_inventory \
--output-bigquery-table=resources \
--content-type=resource
Step 2: Audit IAM Policies and Bindings
Review IAM policies across the organization for overly permissive bindings, primitive roles, and service account misuse.
gcloud organizations get-iam-policy ORG_ID \
--format=json > org-iam-policy.json
gcloud asset search-all-iam-policies \
--scope=organizations/ORG_ID \
--query="policy:roles/owner OR policy:roles/editor" \
--format="table(resource, policy.bindings.role, policy.bindings.members)"
gcloud asset search-all-iam-policies \
--scope=organizations/ORG_ID \
--query="policy.bindings.members:serviceAccount AND policy:roles/owner" \
--format=json
gcloud asset search-all-iam-policies \
--scope=organizations/ORG_ID \
--query="policy:allUsers OR policy:allAuthenticatedUsers" \
--format="table(resource, policy.bindings.role, policy.bindings.members)"
gcloud iam service-accounts keys list \
--iam-account=SA_EMAIL \
--managed-by=user \
--format="table(name,validAfterTime,validBeforeTime)"
Step 3: Assess Firewall Rules and Network Configuration
Audit VPC firewall rules for overly permissive ingress rules, missing logging, and network exposure.
gcloud compute firewall-rules list \
--filter="direction=INGRESS AND sourceRanges=0.0.0.0/0" \
--format="table(name, network, allowed, sourceRanges, targetTags)"
gcloud compute firewall-rules list \
--filter="direction=INGRESS AND allowed[].IPProtocol=all" \
--format="table(name, network, sourceRanges, targetTags)"
gcloud compute firewall-rules list \
--filter="direction=INGRESS AND sourceRanges=0.0.0.0/0 AND (allowed[].ports=22 OR allowed[].ports=3389)" \
--format="table(name, network, allowed, sourceRanges)"
gcloud compute networks subnets list \
--format="table(name, region, enableFlowLogs, logConfig.aggregationInterval)"
Step 4: Audit Cloud Storage Bucket Permissions
Check for publicly accessible storage buckets and missing encryption configurations.
gsutil ls -p PROJECT_ID
for bucket in $(gsutil ls -p PROJECT_ID); do
echo "=== $bucket ==="
gsutil iam get "$bucket" | grep -E "allUsers|allAuthenticatedUsers" && \
echo " WARNING: PUBLIC ACCESS DETECTED" || \
echo " OK: No public access"
done
for bucket in $(gsutil ls -p PROJECT_ID); do
echo "=== $bucket ==="
gsutil kms encryption "$bucket" 2>/dev/null || echo " Using Google-managed encryption"
done
for bucket in $(gsutil ls -p PROJECT_ID); do
gsutil uniformbucketlevelaccess get "$bucket"
done
Step 5: Run ScoutSuite for Comprehensive Assessment
Execute ScoutSuite for an automated multi-check security assessment of the GCP environment.
python3 -m ScoutSuite gcp \
--user-account \
--all-projects \
--report-dir ./scoutsuite-gcp-report
python3 -m ScoutSuite gcp \
--service-account /path/to/service-account-key.json \
--all-projects \
--report-dir ./scoutsuite-gcp-report
open ./scoutsuite-gcp-report/gcp-report.html
Step 6: Query Security Command Center Findings
Retrieve and analyze SCC findings for vulnerabilities, misconfigurations, and threats.
gcloud scc findings list ORG_ID \
--filter="state=\"ACTIVE\" AND severity=\"CRITICAL\"" \
--format="table(finding.category, finding.severity, finding.resourceName, finding.eventTime)"
gcloud scc findings list ORG_ID \
--filter="state=\"ACTIVE\" AND category=\"PUBLIC_BUCKET_ACL\"" \
--format=json
gcloud scc findings group ORG_ID \
--group-by="category" \
--filter="state=\"ACTIVE\""
gcloud scc findings list ORG_ID \
--filter="state=\"ACTIVE\" AND sourceProperties.compliance_standard=\"CIS\"" \
--format="table(finding.category, finding.severity, finding.resourceName)"
Key Concepts
| Term | Definition |
|---|
| Security Command Center | GCP-native security and risk management platform that provides asset inventory, vulnerability detection, and threat monitoring |
| Forseti Security | Open-source GCP security toolkit (now deprecated in favor of SCC) that provided inventory, scanning, enforcement, and notification capabilities |
| Cloud Asset Inventory | GCP service that provides a complete inventory of cloud resources with metadata, IAM policies, and org policy configurations |
| CIS GCP Foundations Benchmark | Security best practice guidelines from Center for Internet Security specific to Google Cloud Platform configuration |
| Uniform Bucket-Level Access | GCP storage setting that disables legacy ACLs and enforces access exclusively through IAM policies for consistent access control |
| Organization Policy | GCP constraint-based governance mechanism that restricts resource configurations across the organization hierarchy |
Tools & Systems
- Security Command Center: GCP-native CSPM providing asset inventory, vulnerability findings, and compliance scoring
- ScoutSuite: Multi-cloud security auditing tool with comprehensive GCP checks for IAM, compute, storage, and networking
- gcloud CLI: Primary command-line interface for querying GCP resource configurations and security settings
- Cloud Asset Inventory: API for searching and exporting resource metadata and IAM policies across GCP projects
- Forseti Security: Legacy open-source GCP security toolkit, superseded by SCC but still referenced in compliance frameworks
Common Scenarios
Scenario: Assessing a Newly Acquired GCP Organization
Context: After a company acquisition, the security team needs to assess the security posture of the acquired company's GCP organization with 30+ projects.
Approach:
- Enable Cloud Asset API and export full resource inventory to BigQuery for analysis
- Run
gcloud asset search-all-iam-policies to find all Owner/Editor bindings and public access grants
- Audit firewall rules across all projects for overly permissive ingress from
0.0.0.0/0
- Check all storage buckets for public access using
gsutil iam get
- Run ScoutSuite for a comprehensive automated assessment with HTML report
- Enable SCC and review all CRITICAL and HIGH findings
- Generate a risk-prioritized remediation roadmap for the integration team
Pitfalls: GCP IAM bindings are inherited from organization to folder to project. A permissive binding at the organization level affects all downstream projects. Always audit IAM at every level of the hierarchy, not just at the project level.
Output Format
GCP Security Assessment Report
=================================
Organization: acme-acquired-org (ORG_ID: 123456789)
Projects Assessed: 34
Assessment Date: 2026-02-23
Standards: CIS GCP Foundations 2.0
IAM FINDINGS:
Users with Owner role at org level: 3
Service accounts with Editor role: 12
Resources with allUsers binding: 5
Service account keys > 90 days: 18
NETWORK FINDINGS:
Firewall rules allowing 0.0.0.0/0: 14
SSH open to internet: 7
RDP open to internet: 2
Subnets without VPC flow logs: 22
STORAGE FINDINGS:
Publicly accessible buckets: 5
Buckets without CMEK encryption: 28
Buckets without uniform access: 15
CRITICAL FINDINGS: 12
HIGH FINDINGS: 34
MEDIUM FINDINGS: 78
LOW FINDINGS: 145
TOP REMEDIATION PRIORITIES:
1. Remove allUsers bindings from 5 storage buckets (CRITICAL)
2. Restrict 0.0.0.0/0 firewall rules to specific CIDRs (HIGH)
3. Rotate 18 service account keys older than 90 days (HIGH)
4. Enable VPC flow logs on 22 subnets (MEDIUM)
