CSPM on a Budget: Prowler, Checkov, and ScoutSuite vs Expensive Vendor Lock-In

# CSPM on a Budget: Prowler, Checkov, and ScoutSuite vs Expensive Vendor Lock-In

The average cloud misconfiguration takes 88 days to detect. Not because it's hard to find — a single scan would catch it — but because most teams don't scan at all, or they scan quarterly when compliance requires it. Meanwhile, attackers are scanning your infrastructure continuously.

Enterprise CSPM vendors (Wiz, Prisma Cloud, Lacework) charge $50-200K/year and they're worth it for large organizations. But if your cloud bill is under $100K/month, you can get 80% of the value with open-source tools running in CI/CD. We run all three — Prowler, Checkov, and ScoutSuite — and here's exactly how they compare.

What CSPM Actually Catches

Before comparing tools, let's ground this in reality. These are the top 10 misconfigurations we find across client AWS accounts:

|---|-----------------|----------|------------|

*Based on our scans across 40+ client AWS accounts in 2025-2026.*

Every tool in this comparison catches all 10. The differences are in how they report, how they integrate, and what else they catch beyond the basics.

Prowler: The AWS-Native Powerhouse

Prowler started as an AWS-only tool and it shows — AWS coverage is the deepest of any open-source CSPM. It now supports Azure and GCP, but AWS is where it shines with 300+ checks mapped to CIS, NIST 800-53, GDPR, HIPAA, SOC2, and PCI-DSS.

Running Prowler

# Install
pip install prowler

# Full AWS scan with CIS Benchmark
prowler aws --compliance cis_2.0_aws

# Scan specific services only (faster for CI/CD)
prowler aws -s s3 ec2 iam rds lambda

# Output formats — HTML for humans, JSON for automation
prowler aws --compliance cis_2.0_aws \
  -M html json csv \
  --output-directory /reports/prowler/

# Scan specific AWS account with assumed role
prowler aws \
  --role arn:aws:iam::123456789012:role/ProwlerAuditRole \
  --region us-east-1 us-west-2 eu-west-1

# Suppress known acceptable findings
prowler aws --allowlist-file allowlist.yaml

Prowler Allowlist for Accepted Risks

# allowlist.yaml — document WHY each exception exists
Accounts:
  "123456789012":
    Checks:
      # Dev VPC intentionally has broad SGs for testing
      "ec2_securitygroup_allow_ingress_from_internet_to_any_port":
        Regions:
          - "us-east-1"
        Resources:
          - "sg-0abc123dev"
        Comment: "Dev environment SG — isolated VPC, no production data"
        Approved_by: "security-team"
        Expiry: "2026-06-30"
      
      # Legacy app requires unencrypted RDS (migration planned Q3)
      "rds_instance_storage_encrypted":
        Resources:
          - "legacy-app-db"
        Comment: "Migration to encrypted instance scheduled for 2026-Q3"
        Approved_by: "cto"
        Expiry: "2026-09-30"

Prowler CI/CD Integration

# .github/workflows/security-scan.yml
name: Cloud Security Scan
on:
  schedule:
    - cron: '0 6 * * *'  # Daily at 6 AM UTC
  push:
    paths:
      - 'terraform/**'
      - 'cloudformation/**'

jobs:
  prowler-scan:
    runs-on: ubuntu-latest
    permissions:
      id-token: write
      contents: read
    steps:
      - uses: actions/checkout@v4
      
      - name: Configure AWS credentials
        uses: aws-actions/configure-aws-credentials@v4
        with:
          role-to-assume: arn:aws:iam::123456789012:role/ProwlerCI
          aws-region: us-east-1
      
      - name: Run Prowler
        run: |
          pip install prowler
          prowler aws -s s3 ec2 iam rds \
            --compliance cis_2.0_aws \
            --severity critical high \
            -M json \
            --status FAIL \
            --output-directory results/
      
      - name: Check for critical findings
        run: |
          CRITICAL=$(cat results/*.json | \
            python3 -c "import sys,json; \
            data=json.load(sys.stdin); \
            print(sum(1 for f in data if f.get('Severity','')=='critical'))")
          if [ "$CRITICAL" -gt 0 ]; then
            echo "::error::$CRITICAL critical security findings detected"
            exit 1
          fi
      
      - name: Upload report
        uses: actions/upload-artifact@v4
        with:
          name: prowler-report
          path: results/

Checkov: Infrastructure-as-Code Scanner

Checkov takes a fundamentally different approach — instead of scanning your running cloud infrastructure, it scans your Terraform, CloudFormation, Kubernetes, and Dockerfile code BEFORE deployment. This is shift-left security at its most practical.

What Checkov Scans

Running Checkov

# Install
pip install checkov

# Scan Terraform directory
checkov -d ./terraform/ --framework terraform

# Scan with specific CIS checks only
checkov -d ./terraform/ --check CKV_AWS_18,CKV_AWS_19,CKV_AWS_21

# Scan Kubernetes manifests
checkov -d ./k8s/ --framework kubernetes

# Scan a Dockerfile
checkov --file Dockerfile --framework dockerfile

# Output as JUnit XML for CI integration
checkov -d ./terraform/ -o junitxml > test-results.xml

# Scan Terraform plan (catches dynamic values that static scan misses)
terraform plan -out=tfplan
terraform show -json tfplan > tfplan.json
checkov -f tfplan.json --framework terraform_plan

Custom Checkov Policy

# custom_checks/s3_naming_convention.py
from checkov.terraform.checks.resource.base_resource_check import BaseResourceCheck
from checkov.common.models.enums import CheckResult, CheckCategories

class S3NamingConvention(BaseResourceCheck):
    """Ensure S3 buckets follow our naming convention: {env}-{team}-{purpose}"""
    
    def __init__(self):
        name = "Ensure S3 bucket follows naming convention"
        id = "CUSTOM_AWS_001"
        supported_resources = ["aws_s3_bucket"]
        categories = [CheckCategories.CONVENTION]
        super().__init__(name=name, id=id, categories=categories,
                        supported_resources=supported_resources)
    
    def scan_resource_conf(self, conf):
        bucket_name = conf.get("bucket", [""])[0]
        
        # Must match: {env}-{team}-{purpose}
        # e.g., prod-data-analytics, staging-ml-models
        parts = bucket_name.split("-")
        valid_envs = ["prod", "staging", "dev", "shared"]
        
        if len(parts) >= 3 and parts[0] in valid_envs:
            return CheckResult.PASSED
        return CheckResult.FAILED

check = S3NamingConvention()

Checkov Pre-Commit Hook

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/bridgecrewio/checkov
    rev: '3.2.0'
    hooks:
      - id: checkov
        args:
          - '--compact'
          - '--quiet'
          - '--skip-check'
          - 'CKV_AWS_144,CKV_AWS_145'  # Skip checks not relevant to us

This catches misconfigurations before they even hit a PR. A developer tries to create an unencrypted S3 bucket, Checkov blocks the commit. Zero cloud resources wasted.

ScoutSuite: The Multi-Cloud Auditor

ScoutSuite generates comprehensive HTML reports that are perfect for compliance audits and executive summaries. It scans your running infrastructure (like Prowler) but with a focus on multi-cloud consistency and readable output.

Running ScoutSuite

# Install
pip install scoutsuite

# AWS scan
scout aws --regions us-east-1,us-west-2,eu-west-1

# GCP scan
scout gcp --project-id my-project-123

# Azure scan  
scout azure --cli

# Generate report with specific rule sets
scout aws --ruleset custom-ruleset.json

# Output to specific directory
scout aws --report-dir /reports/scoutsuite/$(date +%Y-%m-%d)/

Custom ScoutSuite Ruleset

{
  "about": "Custom CSPM ruleset for production accounts",
  "rules": {
    "s3-bucket-no-public-access": {
      "enabled": true,
      "level": "danger"
    },
    "iam-user-no-mfa": {
      "enabled": true,
      "level": "danger"
    },
    "ec2-security-group-opens-all-ports": {
      "enabled": true,
      "level": "danger"
    },
    "rds-instance-no-encryption": {
      "enabled": true,
      "level": "warning"
    },
    "cloudtrail-no-log-file-validation": {
      "enabled": true,
      "level": "warning"
    }
  }
}

ScoutSuite's Strength: The Report

ScoutSuite's HTML report is its killer feature. It generates an interactive, self-contained HTML file that you can send to a compliance officer, a CISO, or an auditor. No login required, no SaaS portal access needed. We send these monthly to clients as part of our managed security offering.

Tool Comparison Matrix

|-----------|---------|---------|------------|

Our Production Stack: All Three Together

We don't pick one — we run all three at different stages:

Developer writes Terraform
         │
         ▼
   ┌──────────┐
   │ Checkov   │ ← Pre-commit hook + CI pipeline
   │ (IaC scan)│   Catches misconfigs BEFORE deploy
   └─────┬────┘
         │ Passes? ──No──▶ PR blocked, dev fixes
         │
         ▼ Yes
   Terraform Apply
         │
         ▼
   ┌──────────┐
   │ Prowler   │ ← Daily cron, scans running infra
   │ (Runtime) │   Catches drift + runtime-only issues
   └─────┬────┘
         │
         ▼
   ┌───────────┐
   │ ScoutSuite │ ← Weekly, generates compliance reports
   │ (Audit)    │   Beautiful HTML for stakeholders
   └────────────┘

Cost of This Stack

The enterprise tools add cloud-native agent deployment, real-time detection, and attack path analysis. Those matter at scale. But for teams with 1-5 AWS accounts, the open-source stack catches the misconfigurations that actually cause breaches.

Quick Start: 15 Minutes to Your First Scan

# Install all three
pip install prowler checkov scoutsuite

# Quick Prowler scan (critical findings only)
prowler aws --severity critical -M json --status FAIL

# Quick Checkov scan on your Terraform
checkov -d ./terraform/ --compact --quiet

# Quick ScoutSuite report
scout aws --regions us-east-1
# Open the HTML report in scoutsuite-report/

Run these three commands and you'll know more about your cloud security posture in 15 minutes than most teams learn in a quarter.

Beyond Scanning: Building a Security Culture

The tools are the easy part. The hard part is making your team actually fix the findings. Our approach:

1. Categorize: Critical = fix in 24h, High = fix in 7 days, Medium = fix in 30 days 2. Assign: Every finding gets an owner, not a team 3. Track: Findings go into Jira/Linear, not a PDF that gets forgotten 4. Prevent: Every finding that could have been caught pre-deploy gets a Checkov rule 5. Measure: Track mean-time-to-remediate monthly — it should trend down

Want help setting up automated cloud security scanning for your infrastructure? Our security team has deployed this stack across dozens of AWS, GCP, and Azure environments. [Book a free assessment at techsaas.cloud/contact](https://techsaas.cloud/contact) — we'll run your first scan and walk through the findings together.