auditing-cloud-with-cis-benchmarks

This skill details how to conduct cloud security audits using Center for Internet Security benchmarks for AWS, Azure, and GCP. It covers interpreting CIS Foundations Benchmark controls, running automated assessments with tools like Prowler and ScoutSuite, remediating failed controls, and maintaining continuous compliance monitoring against CIS v5 for AWS, v4 for Azure, and v4 for GCP.

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Last source activity: March 16, 2026 at 00:29
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name	auditing-cloud-with-cis-benchmarks
description	This skill details how to conduct cloud security audits using Center for Internet Security benchmarks for AWS, Azure, and GCP. It covers interpreting CIS Foundations Benchmark controls, running automated assessments with tools like Prowler and ScoutSuite, remediating failed controls, and maintaining continuous compliance monitoring against CIS v5 for AWS, v4 for Azure, and v4 for GCP.
domain	cybersecurity
subdomain	cloud-security
tags	["cis-benchmarks","cloud-audit","compliance-assessment","prowler","security-hardening"]
version	1.0.0
author	mahipal
license	Apache-2.0

Auditing Cloud with CIS Benchmarks

When to Use

When performing initial security audits of cloud environments against industry-standard benchmarks
When preparing for SOC 2, ISO 27001, or regulatory audits that reference CIS controls
When establishing a measurable security baseline for new cloud accounts or subscriptions
When tracking compliance improvement over time with periodic reassessment
When evaluating the security posture of acquired or inherited cloud environments

Do not use for runtime threat detection (see detecting-cloud-threats-with-guardduty), for application-level security testing (see conducting-cloud-penetration-testing), or for compliance frameworks not based on CIS (refer to specific regulatory skill files).

Prerequisites

Read-only access to target cloud accounts (AWS SecurityAudit policy, Azure Reader role, GCP Viewer role)
Prowler, ScoutSuite, or cloud-native CSPM tools installed and configured
Understanding of CIS benchmark structure: sections, controls, profiles (Level 1 and Level 2)
Remediation access for implementing fixes (separate from audit credentials)

Workflow

Step 1: Select Appropriate CIS Benchmark Version

Choose the correct benchmark version for each cloud provider. Current versions as of 2025 include CIS AWS Foundations Benchmark v5.0, CIS Azure Foundations Benchmark v4.0, and CIS GCP Foundations Benchmark v4.0.

CIS Benchmark Coverage Areas:
+-------------------+-------------------------+------------------------+
| Section           | AWS v5.0                | Azure v4.0             |
+-------------------+-------------------------+------------------------+
| Identity & Access | IAM policies, MFA, root | Azure AD, RBAC, PIM    |
| Logging           | CloudTrail, Config      | Activity Log, Diag     |
| Monitoring        | CloudWatch alarms       | Defender, Sentinel     |
| Networking        | VPC, SG, NACLs         | NSG, ASG, Firewall     |
| Storage           | S3 encryption, access   | Storage encryption     |
| Database          | RDS encryption          | SQL TDE, auditing      |
+-------------------+-------------------------+------------------------+

CIS Profile Levels:
  Level 1: Practical security settings that can be implemented without significant
           performance impact or reduced functionality
  Level 2: Defense-in-depth settings that may reduce functionality or require
           additional planning for implementation

Step 2: Run Automated Assessment with Prowler

Execute comprehensive CIS benchmark scans using Prowler for automated control evaluation across AWS, Azure, and GCP.

# AWS CIS v5.0 assessment
prowler aws \
  --compliance cis_5.0_aws \
  --profile audit-account \
  --output-formats json-ocsf,html,csv \
  --output-directory ./cis-audit-$( +%Y%m%d)


prowler azure \
  --compliance cis_4.0_azure \
  --subscription-ids  \
  --output-formats json-ocsf,html,csv \
  --output-directory ./cis-audit-azure-$( +%Y%m%d)


prowler gcp \
  --compliance cis_4.0_gcp \
  --project-ids  \
  --output-formats json-ocsf,html,csv \
  --output-directory ./cis-audit-gcp-$( +%Y%m%d)


scout suite aws \
  --profile audit-account \
  --report-dir ./scout-report \
  --ruleset cis-5.0 \
  --force

# Parse Prowler results for failed controls
cat ./cis-audit-*/prowler-output-*.json | \
  jq '[.[] | select(.StatusExtended == "FAIL")] | group_by(.CheckID) |
  map({control: .[0].CheckID, description: .[0].CheckTitle,
  failed_resources: length, severity: .[0].Severity}) |
  sort_by(-.failed_resources)'

# Generate compliance score by section
cat ./cis-audit-*/prowler-output-*.json | \
  jq 'group_by(.Section) | map({
    section: .[0].Section,
    total: length,
    passed: [.[] | select(.StatusExtended == "PASS")] | length,
    failed: [.[] | select(.StatusExtended == "FAIL")] | length,
    score: (([.[] | select(.StatusExtended == "PASS")] | length) / length * 100 | round)
  })'

# CIS 1.4: Ensure no root account access key exists
aws iam list-access-keys --user-name root
# If keys exist, delete them
aws iam delete-access-key --user-name root --access-key-id AKIAEXAMPLE

# CIS 2.1.1: Ensure S3 bucket default encryption is enabled
for bucket in $(aws s3api list-buckets --query 'Buckets[*].Name' --output text); do
  aws s3api put-bucket-encryption --bucket "$bucket" \
    --server-side-encryption-configuration '{
      "Rules": [{"ApplyServerSideEncryptionByDefault": {"SSEAlgorithm": "AES256"}}]
    }' 2>/dev/null && echo "Encrypted: $bucket" || echo "FAILED: $bucket"
done

# CIS 3.1: Ensure CloudTrail is enabled in all regions
aws cloudtrail create-trail \
  --name organization-trail \
  --s3-bucket-name cloudtrail-logs-bucket \
  --is-multi-region-trail \
  --enable-log-file-validation \
  --kms-key-id arn:aws:kms:us-east-1:123456789012:key/key-id

aws cloudtrail start-logging --name organization-trail

# CIS 4.x: Configure CloudWatch metric filters and alarms
aws logs put-metric-filter \
  --log-group-name CloudTrail/DefaultLogGroup \
  --filter-name UnauthorizedAPICalls \
  --filter-pattern '{ ($.errorCode = "*UnauthorizedAccess*") || ($.errorCode = "AccessDenied*") }' \
  --metric-transformations metricName=UnauthorizedAPICalls,metricNamespace=CISBenchmark,metricValue=1

# AWS: Enable CIS v5.0 in Security Hub
aws securityhub batch-enable-standards \
  --standards-subscription-requests '[
    {"StandardsArn": "arn:aws:securityhub:::ruleset/cis-aws-foundations-benchmark/v/5.0.0"}
  ]'

# Azure: Assign CIS benchmark policy initiative
az policy assignment create \
  --name cis-azure-benchmark \
  --scope "/subscriptions/<sub-id>" \
  --policy-set-definition "1a5bb27d-173f-493e-9568-eb56638dbd0e" \
  --params '{"effect": {"value": "AuditIfNotExists"}}'

# Schedule periodic Prowler assessments
# Run weekly via cron or CI/CD pipeline
0 2 * * 1 prowler aws --compliance cis_5.0_aws --output-formats csv --output-directory /opt/audits/weekly-$(date +\%Y\%m\%d)

Term	Definition
CIS Benchmark	Prescriptive security configuration guidelines developed by the Center for Internet Security through community consensus
Level 1 Profile	Practical security controls implementable without significant performance or functionality impact, representing security hygiene
Level 2 Profile	Defense-in-depth controls that may restrict functionality and require careful planning before implementation
Foundations Benchmark	CIS benchmark specifically for cloud providers covering IAM, logging, monitoring, networking, and storage security
Control ID	Unique numerical identifier for each CIS recommendation (e.g., 1.4 for root access key checks, 2.1.1 for S3 encryption)
Compliance Score	Percentage of CIS controls in a passing state, tracked over time to measure security posture improvement
Automated Assessment	Tool-driven evaluation of CIS controls using cloud provider APIs to check resource configurations against benchmark requirements
Remediation Runbook	Documented step-by-step procedure for fixing a specific failed CIS control, including pre-checks and validation

CIS Benchmark Audit Report
============================
Cloud Provider: AWS
Benchmark Version: CIS AWS Foundations Benchmark v5.0
Accounts Assessed: 45
Assessment Date: 2025-02-23
Tool: Prowler v4.3.0

OVERALL COMPLIANCE SCORE: 74%

COMPLIANCE BY SECTION:
  1. Identity and Access Management:  68% (41/60 controls passed)
  2. Storage:                         82% (28/34 controls passed)
  3. Logging:                         91% (20/22 controls passed)
  4. Monitoring:                      55% (18/33 controls passed)
  5. Networking:                      78% (32/41 controls passed)

TOP FAILED CONTROLS (by affected accounts):
  [1.4]   Root account has active access keys           - 3/45 accounts
  [1.5]   MFA not enabled for root account              - 2/45 accounts
  [2.1.1] S3 default encryption not enabled             - 12/45 accounts
  [3.1]   CloudTrail not multi-region                   - 8/45 accounts
  [4.3]   No alarm for root account usage               - 28/45 accounts
  [5.1]   VPC flow logs not enabled                     - 15/45 accounts
  [5.4]   Security groups allow 0.0.0.0/0 ingress      - 22/45 accounts

REMEDIATION PRIORITY:
  Critical (Fix within 7 days):  Root access keys, missing root MFA
  High (Fix within 30 days):     S3 encryption, CloudTrail, VPC flow logs
  Medium (Fix within 60 days):   CloudWatch alarms, security group restrictions
  Low (Fix within 90 days):      Level 2 controls, informational items