Auditing GCP IAM Permissions
When to Use
- When performing security assessments of GCP organization or project IAM configurations
- When identifying service accounts with excessive permissions or unused access
- When compliance requirements mandate review of access controls and role assignments
- When investigating potential lateral movement through IAM misconfigurations
- When reducing the blast radius of compromised credentials by scoping down permissions
Do not use for VPC firewall rule auditing (use network security tools), for GKE RBAC auditing (use Kubernetes-specific RBAC tools), or for real-time threat detection on IAM actions (use SCC Event Threat Detection).
Prerequisites
- GCP organization or project with
roles/iam.securityReviewer and roles/cloudAsset.viewer
- gcloud CLI authenticated with appropriate permissions
- Cloud Asset API enabled (
gcloud services enable cloudasset.googleapis.com)
- IAM Recommender API enabled (
gcloud services enable recommender.googleapis.com)
- Policy Analyzer API enabled (
gcloud services enable policyanalyzer.googleapis.com)
Workflow
Step 1: Enumerate IAM Bindings Across the Organization
List all IAM bindings at organization, folder, and project levels to understand the full access landscape.
gcloud organizations get-iam-policy ORG_ID \
--format=json > org-iam-policy.json
gcloud asset search-all-iam-policies \
--scope=organizations/ORG_ID \
--format="table(resource, policy.bindings.role, policy.bindings.members)" \
--limit=500
gcloud asset search-all-iam-policies \
--scope=organizations/ORG_ID \
--query="policy:roles/owner" \
--format="table(resource, policy.bindings.members)"
gcloud asset search-all-iam-policies \
--scope=organizations/ORG_ID \
--query="policy:roles/owner OR policy:roles/editor" \
--format=json | python3 -c "
import json, sys
data = json.load(sys.stdin)
for result in data:
resource = result.get('resource', '')
for binding in result.get('policy', {}).get('bindings', []):
role = binding.get('role', '')
if role in ['roles/owner', 'roles/editor']:
for member in binding.get('members', []):
print(f'{resource} | {role} | {member}')
"
Step 2: Audit Service Accounts and Their Keys
Identify service accounts with excessive permissions, user-managed keys, and unused accounts.
gcloud iam service-accounts list \
--project=PROJECT_ID \
--format="table(email, displayName, disabled)"
for sa in $(gcloud iam service-accounts list --project=PROJECT_ID --format="value(email)"); do
keys=$(gcloud iam service-accounts keys list \
--iam-account="$sa" \
--managed-by=user \
--format="table(name.basename(),validAfterTime,validBeforeTime)")
if [ -n "$keys" ]; then
echo "=== $sa ==="
echo "$keys"
fi
done
gcloud asset search-all-iam-policies \
--scope=organizations/ORG_ID \
--query="policy.bindings.members:serviceAccount AND (policy:roles/owner OR policy:roles/editor OR policy:admin)" \
--format="table(resource, policy.bindings.role, policy.bindings.members)"
for sa in $(gcloud iam service-accounts list --project=PROJECT_ID --format="value(email)"); do
echo "=== $sa ==="
gcloud iam service-accounts get-iam-policy "$sa" --format=json 2>/dev/null
done
Step 3: Use IAM Recommender to Identify Excess Permissions
Leverage GCP's IAM Recommender to find roles that grant more access than actually used.
gcloud recommender recommendations list \
--project=PROJECT_ID \
--recommender=google.iam.policy.Recommender \
--location=global \
--format="table(name, description, priority, stateInfo.state)"
gcloud recommender recommendations describe RECOMMENDATION_ID \
--project=PROJECT_ID \
--recommender=google.iam.policy.Recommender \
--location=global \
--format=json
gcloud recommender insights list \
--project=PROJECT_ID \
--insight-type=google.iam.policy.Insight \
--location=global \
--format="table(name, description, severity, category)"
gcloud recommender recommendations mark-claimed RECOMMENDATION_ID \
--project=PROJECT_ID \
--recommender=google.iam.policy.Recommender \
--location=global \
--etag=ETAG
Step 4: Analyze Effective Permissions with Policy Analyzer
Use Policy Analyzer to determine effective access for specific principals or resources.
gcloud asset analyze-iam-policy \
--organization=ORG_ID \
--full-resource-name="//storage.googleapis.com/projects/_/buckets/sensitive-data-bucket" \
--format="table(identityList.identities, accessControlLists.accesses.role)"
gcloud asset analyze-iam-policy \
--organization=ORG_ID \
--identity="user:developer@company.com" \
--format="table(accessControlLists.resources.fullResourceName, accessControlLists.accesses.role)"
gcloud asset analyze-iam-policy \
--organization=ORG_ID \
--full-resource-name="//cloudresourcemanager.googleapis.com/projects/PROJECT_ID" \
--permissions="iam.serviceAccounts.actAs,iam.serviceAccountKeys.create" \
--format="table(identityList.identities, accessControlLists.accesses.permission)"
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)"
Step 5: Check for Domain-Wide Delegation and Impersonation Risks
Identify service accounts with domain-wide delegation and impersonation capabilities.
gcloud iam service-accounts list --project=PROJECT_ID --format=json | python3 -c "
import json, sys
accounts = json.load(sys.stdin)
for sa in accounts:
email = sa.get('email', '')
# Check if the SA has domain-wide delegation enabled
# This requires Admin SDK API access
print(f'SA: {email} - Check admin.google.com for delegation status')
"
for sa in $(gcloud iam service-accounts list --project=PROJECT_ID --format="value(email)"); do
policy=$(gcloud iam service-accounts get-iam-policy "$sa" --format=json 2>/dev/null)
if echo "$policy" | python3 -c "
import json, sys
p = json.load(sys.stdin)
for b in p.get('bindings', []):
if b['role'] in ['roles/iam.serviceAccountTokenCreator', 'roles/iam.serviceAccountUser']:
print(f' {b[\"role\"]}: {b[\"members\"]}')
" 2>/dev/null; then
echo "=== Impersonation risk: $sa ==="
fi
done
Step 6: Generate Audit Report and Apply Remediation
Compile findings and implement recommended permission reductions.
gcloud projects remove-iam-policy-binding PROJECT_ID \
--member="user:developer@company.com" \
--role="roles/editor"
gcloud projects add-iam-policy-binding PROJECT_ID \
--member="user:developer@company.com" \
--role="roles/compute.viewer"
gcloud projects add-iam-policy-binding PROJECT_ID \
--member="user:developer@company.com" \
--role="roles/storage.objectViewer"
gcloud iam service-accounts keys delete KEY_ID \
--iam-account=SA_EMAIL
gcloud iam service-accounts disable SA_EMAIL --project=PROJECT_ID
Key Concepts
| Term | Definition |
|---|
| Primitive Role | Legacy GCP roles (Owner, Editor, Viewer) that grant broad permissions across all services, not recommended for production |
| Predefined Role | GCP-managed role scoped to specific services and actions, providing more granular access than primitive roles |
| IAM Recommender | GCP ML-based service that analyzes actual permission usage and suggests role reductions to achieve least privilege |
| Policy Analyzer | Tool for analyzing effective IAM access across the organization hierarchy, answering who-can-access-what queries |
| Service Account Key | User-managed credential for service account authentication, a security risk as keys can be exported and do not auto-expire |
| Domain-Wide Delegation | Grants a service account the ability to impersonate any user in the Google Workspace domain, a significant privilege escalation risk |
Tools & Systems
- gcloud CLI: Primary tool for querying and managing GCP IAM policies, service accounts, and role bindings
- IAM Recommender: ML-based recommendation engine for reducing excessive permissions based on actual usage
- Policy Analyzer: Organization-wide effective access analysis tool for understanding who can access what
- Cloud Asset Inventory: Cross-project search for IAM policies and resource metadata
- ScoutSuite: Multi-cloud auditing tool with GCP IAM-specific checks for role assignments and service accounts
Common Scenarios
Scenario: Reducing Primitive Role Usage Across a GCP Organization
Context: An audit reveals that 60% of IAM bindings across the organization use primitive roles (Owner/Editor). The security team needs to migrate to predefined roles without disrupting developer workflows.
Approach:
- Run
gcloud asset search-all-iam-policies to inventory all primitive role bindings
- Use IAM Recommender to get ML-based suggestions for replacement predefined roles
- For each binding, use Policy Analyzer to understand what the principal actually accesses
- Create a mapping document: primitive role -> specific predefined roles needed
- Apply predefined roles alongside primitive roles for a testing period
- Monitor for access denied errors using Cloud Audit Logs
- Remove primitive roles after confirming no access issues over 2 weeks
Pitfalls: Primitive roles include permissions across all GCP services, so replacing them requires multiple predefined roles. The Recommender may suggest overly restrictive roles if the observation period does not capture all use cases. Custom roles can fill gaps where no predefined role matches the exact permission set needed.
Output Format
GCP IAM Permissions Audit Report
===================================
Organization: acme-org (ORG_ID: 123456789)
Projects Audited: 25
Audit Date: 2026-02-23
IAM BINDING SUMMARY:
Total bindings: 342
Using primitive roles: 205 (60%)
Using predefined roles: 112 (33%)
Using custom roles: 25 (7%)
CRITICAL FINDINGS:
[IAM-001] Service Account with Owner Role
SA: admin-sa@prod-project.iam.gserviceaccount.com
Role: roles/owner on project prod-project
User-Managed Keys: 3 (oldest: 14 months)
Remediation: Replace with specific predefined roles, delete old keys
[IAM-002] allAuthenticatedUsers Binding
Resource: gs://public-data-bucket
Role: roles/storage.objectViewer
Risk: Any Google account holder can read bucket contents
Remediation: Restrict to specific user groups or service accounts
SERVICE ACCOUNT HEALTH:
Total service accounts: 67
With user-managed keys: 23
Keys older than 90 days: 18
Unused accounts (90+ days): 12
With domain-wide delegation: 2
RECOMMENDER SUGGESTIONS:
Total recommendations: 45
Priority HIGH: 12
Estimated permissions reduced: 2,847 individual permissions
