Prowler vs Scout Suite vs Cloud Custodian: Self-Hosted Cloud Security Audit Guide 2026

Cloud environments expand quickly, and with every new service or account comes a new attack surface. Commercial Cloud Security Posture Management (CSPM) platforms charge premium prices for capabilities you can run yourself with open-source tools.

This guide compares three of the most capable self-hosted cloud security auditing and policy enforcement tools available in 2026: Prowler, Scout Suite, and Cloud Custodian. Each takes a different approach to cloud security, and together they cover assessment, auditing, and automated remediation.

Why Self-Host Your Cloud Security Auditing

Commercial CSPM tools like Wiz, Orca Security, and Prisma Cloud offer powerful features but come with significant costs, vendor lock-in, and the requirement to grant broad cloud permissions to a third-party SaaS. Self-hosting your security auditing tools provides:

• Full data ownership — scan results, findings, and remediation logs never leave your infrastructure
• Unlimited scans — no per-account or per-scan pricing tiers
• Custom policies — write checks specific to your compliance requirements (SOC 2, HIPAA, PCI DSS, internal standards)
• CI/CD integration — embed security checks directly into deployment pipelines
• Multi-cloud from day one — most open-source tools support AWS, Azure, and GCP out of the box

For teams running Kubernetes workloads, pairing a CSPM tool with container image scanning and Kubernetes policy enforcement creates a comprehensive security posture.

Prowler: Comprehensive Cloud Security Platform

GitHub: prowler-cloud/prowler · 13,668 stars · Updated: April 2026 · Python

Prowler is the most widely used open-source cloud security platform. It performs over 300 security checks across AWS, Azure, GCP, and Kubernetes environments, mapping findings to CIS Benchmarks, PCI DSS, HIPAA, GDPR, SOC 2, and other compliance frameworks.

What sets Prowler apart in 2026 is its full-stack architecture — it’s no longer just a CLI scanner. The platform includes a REST API, a React-based dashboard UI, a Neo4j graph database for finding correlation, and even an MCP (Model Context Protocol) server for integrations.

Key Features

• 300+ security checks across AWS, Azure, GCP, and Kubernetes
• Compliance frameworks — CIS, ENS, PCI DSS, HIPAA, GDPR, SOC 2, FedRAMP, MITRE ATT&CK
• Full-stack platform — API, dashboard UI, PostgreSQL, Valkey cache, Neo4j graph database
• Scheduling and reporting — automated recurring scans with email/Slack notifications
• MCP server — automated security analysis via standardized protocol
• Role-based access control — multi-tenant user management
• Custom checks — write your own security policies in Python

Quick Install

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# Install via pip
pip install prowler

# Run a quick assessment against AWS
prowler aws --profile default --checks-group cis

# Run all checks and generate HTML + CSV + JSON reports
prowler aws --profile default --output-formats html,csv,json --output-dir ./prowler-reports

Docker Compose Deployment

Prowler’s production deployment uses Docker Compose with six services — API, UI, PostgreSQL, Valkey (Redis-compatible cache), Neo4j, and an MCP server:

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# docker-compose.yml
services:
  api:
    image: prowlercloud/prowler-api:stable
    env_file: .env
    ports:
      - "8080:8080"
    volumes:
      - ./_data/api:/home/prowler/.config/prowler-api
      - output:/tmp/prowler_api_output
    depends_on:
      postgres:
        condition: service_healthy
      valkey:
        condition: service_healthy

  ui:
    image: prowlercloud/prowler-ui:stable
    env_file: .env
    ports:
      - "3000:3000"
    depends_on:
      - api

  postgres:
    image: postgres:16.3-alpine3.20
    volumes:
      - ./_data/postgres:/var/lib/postgresql/data
    environment:
      POSTGRES_USER: ${POSTGRES_ADMIN_USER}
      POSTGRES_PASSWORD: ${POSTGRES_ADMIN_PASSWORD}
      POSTGRES_DB: ${POSTGRES_DB}
    ports:
      - "5432:5432"
    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${POSTGRES_ADMIN_USER}"]
      interval: 5s
      timeout: 5s
      retries: 5

  valkey:
    image: valkey/valkey:7-alpine3.19
    volumes:
      - ./_data/valkey:/data
    ports:
      - "6379:6379"
    healthcheck:
      test: ["CMD-SHELL", "valkey-cli ping"]
      interval: 10s

  mcp-server:
    image: prowlercloud/prowler-mcp:stable
    ports:
      - "8000:8000"
    command: ["uvicorn", "--host", "0.0.0.0", "--port", "8000"]
    healthcheck:
      test: ["CMD-SHELL", "wget -q -O /dev/null http://127.0.0.1:8000/health || exit 1"]
      interval: 10s

  worker:
    image: prowlercloud/prowler-api:stable
    env_file: .env
    volumes:
      - "output:/tmp/prowler_api_output"
    depends_on:
      api:
        condition: service_healthy
    entrypoint: ["/home/prowler/docker-entrypoint.sh", "worker"]

volumes:
  output:
    driver: local

The .env file configures credentials, ports, and database settings. After docker compose up -d, the dashboard is available at http://localhost:3000.

Scout Suite: Multi-Cloud Security Assessment

GitHub: nccgroup/ScoutSuite · 7,637 stars · Updated: September 2025 · Python

Scout Suite, developed by NCC Group, is a focused multi-cloud security auditing tool. Unlike Prowler’s full-stack platform approach, Scout Suite is a lightweight CLI that generates interactive HTML reports of your cloud environment’s security posture.

The tool enumerates cloud resources via each provider’s API, evaluates configurations against security best practices, and produces a self-contained HTML report with findings categorized by risk level. This makes it ideal for point-in-time audits, penetration testing engagements, and compliance assessments.

Key Features

• Multi-cloud support — AWS, Azure, GCP, Alibaba Cloud, Oracle Cloud, DigitalOcean, Kubernetes
• Interactive HTML reports — self-contained, no server required
• No persistent infrastructure — run once, get a report, done
• Provider-specific checks — 100+ AWS checks, 70+ Azure checks, 50+ GCP checks
• Lightweight — single Docker image, no database dependencies
• Custom rules — extend with Python-based rule files

Quick Install

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# Install via pip
pip install scoutsuite

# Run an AWS assessment
scout aws --profile default

# Run an Azure assessment
scout azure --cli

# Run a GCP assessment
scout gcp --project-id my-project

# Reports are saved to scout-report/ as HTML files

Docker Deployment

Scout Suite runs from a single Docker container with cloud credentials mounted as volumes:

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# Build from the official Dockerfile
FROM python:3.12

# Install cloud CLI tools
RUN pip install awscli azure-cli google-cloud-sdk

# Install Scout Suite
RUN pip install scoutsuite

# Mount AWS credentials at runtime
# docker run -v ~/.aws:/root/.aws -v $(pwd)/report:/report scoutsuite:latest scout aws

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# Run with AWS credentials
docker run -it \
  -v ~/.aws:/root/.aws:ro \
  -v $(pwd)/report:/report \
  nccgroup/scoutsuite:latest \
  scout aws --profile default --report-dir /report

# Run with Azure CLI authentication
docker run -it \
  -v ~/.azure:/root/.azure:ro \
  -v $(pwd)/report:/report \
  nccgroup/scoutsuite:latest \
  scout azure --report-dir /report

The report directory will contain a scout_report_*.html file that opens directly in any browser — no web server needed.

Cloud Custodian: Policy-Driven Cloud Governance

GitHub: cloud-custodian/cloud-custodian · 5,972 stars · Updated: April 2026 · Python

Cloud Custodian (also known as c7n) takes a fundamentally different approach from Prowler and Scout Suite. Rather than scanning for misconfigurations, it is a rules engine that lets you define policies in YAML to query, filter, and take automated actions on cloud resources.

Think of it as infrastructure-as-code for cloud governance. You write policies like “find all S3 buckets without encryption and enable it” or “terminate any EC2 instance tagged ’test’ older than 7 days,” and Custodian executes them on a schedule or in response to cloud events.

Key Features

• YAML policy language — expressive DSL for resource queries, filters, and actions
• Multi-cloud — AWS, Azure, GCP, Kubernetes (c7n-kube), Terraform (c7n-left)
• Automated remediation — not just detection, but automatic fix actions
• Event-driven — respond to cloud events in real-time via CloudWatch Events / EventBridge
• Cost optimization — identify and remove unused resources
• Extensible — write custom filters and actions in Python
• Multi-account support — c7n-org runs policies across hundreds of accounts

Policy Examples

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# policy.yml — Find and tag unencrypted S3 buckets
- name: s3-unencrypted-tag
  resource: aws.s3
  filters:
    - type: bucket-encryption
      state: False
  actions:
    - type: tag
      key: SecurityRisk
      value: unencrypted

# policy.yml — Stop underutilized EC2 instances
- name: ec7n-stop-idle-instances
  resource: aws.ec2
  filters:
    - type: metrics
      name: CPUUtilization
      days: 7
      value: 5
      op: less-than
  actions:
    - stop

# policy.yml — Delete old EBS snapshots
- name: ebs-cleanup-old-snapshots
  resource: aws.ebs-snapshot
  filters:
    - type: value
      key: CreateDate
      value_type: age
      value: 90
      op: greater-than
  actions:
    - delete

Docker Deployment

Cloud Custodian provides official Docker images for each component:

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# Run a policy against AWS
docker run -it \
  -v ~/.aws:/root/.aws:ro \
  -v $(pwd)/policies:/policies \
  cloudcustodian/c7n:latest \
  run --cache-period 0 /policies/policy.yml

# Run across multiple accounts with c7n-org
docker run -it \
  -v ~/.aws:/root/.aws:ro \
  -v $(pwd)/accounts.yml:/accounts.yml \
  -v $(pwd)/policies:/policies \
  cloudcustodian/c7n-org:latest \
  run -c /accounts.yml -s /output /policies/policy.yml

# Scan Terraform files with c7n-left (no cloud credentials needed)
docker run -it \
  -v $(pwd)/terraform:/terraform \
  cloudcustodian/c7n-left:latest \
  run --tf-dir /terraform --policy /policies/terraform-policy.yml

For scheduled execution, deploy with a cron job or Kubernetes CronJob:

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# kubernetes-cronjob.yml
apiVersion: batch/v1
kind: CronJob
metadata:
  name: cloud-custodian-daily
spec:
  schedule: "0 2 * * *"  # Daily at 2 AM UTC
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: custodian
            image: cloudcustodian/c7n:latest
            command: ["custodian", "run", "--cache-period", "0", "/policies/daily.yml"]
            volumeMounts:
            - name: policies
              mountPath: /policies
            - name: aws-creds
              mountPath: /root/.aws
              readOnly: true
          volumes:
          - name: policies
            configMap:
              name: custodian-policies
          - name: aws-creds
            secret:
              secretName: aws-credentials
          restartPolicy: Never

Feature Comparison

How to Choose

Choose Prowler if you need a complete security platform with a dashboard, scheduled recurring scans, compliance framework mapping, and a modern API. It’s the closest open-source alternative to commercial CSPM platforms like Wiz or Prisma Cloud. The full-stack architecture with PostgreSQL and Neo4j means it requires more resources, but the trade-off is a rich, queryable findings database.

Choose Scout Suite if you need quick, point-in-time security assessments with minimal infrastructure. Its strength is the lightweight, no-dependency model — run it during a penetration test, generate an HTML report, and move on. It supports the widest range of cloud providers including DigitalOcean and Oracle Cloud, which Prowler and Custodian do not cover. For teams that also run IaC security scanning in CI, Scout Suite provides the runtime assessment complement.

Choose Cloud Custodian if you want automated policy enforcement rather than just scanning. Its YAML policy language is powerful enough to replace many manual security operations — automatically tagging, stopping, or deleting non-compliant resources. It’s particularly valuable at scale, where c7n-org can enforce consistent policies across hundreds of AWS accounts. Pair it with runtime security monitoring for comprehensive cloud defense.

FAQ

Which tool is best for compliance auditing?

Prowler has the most comprehensive built-in compliance framework coverage, with checks mapped to CIS Benchmarks, PCI DSS, HIPAA, GDPR, SOC 2, FedRAMP, and MITRE ATT&CK. If your primary goal is to generate compliance reports, Prowler is the best choice. Scout Suite covers CIS and general best practices but has fewer compliance mappings. Cloud Custodian requires you to write custom policies for each compliance requirement.

Can I run all three tools together?

Yes, and this is actually a recommended pattern. Use Scout Suite for quick point-in-time assessments, Prowler for continuous compliance monitoring with its dashboard, and Cloud Custodian for automated remediation of findings. They complement each other rather than overlap completely.

Do these tools require cloud admin permissions?

All three tools need read access to enumerate cloud resources. For remediation actions (Cloud Custodian), write permissions are also required. Best practice is to create a dedicated IAM role or service account with the minimum permissions needed — Prowler provides a permissions directory in its repo with recommended IAM policies for each cloud provider.

How often should I run cloud security scans?

For production environments, daily scans are recommended. Prowler’s built-in scheduler handles this automatically. For Scout Suite, set up a cron job or CI pipeline to run weekly. Cloud Custodian policies can be event-driven (triggered on resource changes) or scheduled — event-driven is ideal for immediate detection of configuration drift.

Can these tools scan on-premises infrastructure?

No, these tools are designed specifically for cloud environments (AWS, Azure, GCP). For on-premises or hybrid infrastructure monitoring, consider tools like Nagios, Icinga, or Cacti for general monitoring, or Wazuh for security-focused endpoint management.

Is there a cost to self-hosting these tools?

The tools themselves are free and open-source. Infrastructure costs are minimal — Scout Suite and Cloud Custodian each run in a single container with negligible resource usage. Prowler’s full-stack deployment requires more resources (PostgreSQL, Neo4j, Valkey, API, UI, and worker services) but still runs comfortably on a small VM or Kubernetes namespace with 4-8 GB RAM.

Which tool supports the most cloud providers?

Scout Suite supports the widest range: AWS, Azure, GCP, Alibaba Cloud, Oracle Cloud, DigitalOcean, and Kubernetes. Prowler supports AWS, Azure, GCP, and Kubernetes. Cloud Custodian supports AWS, Azure, GCP, and Kubernetes. If you need to audit DigitalOcean or Alibaba Cloud, Scout Suite is your only open-source option.