Cloud Security

Cloud security posture assessment skill for detecting IAM privilege escalation, public storage exposure, network configuration risks, and infrastructure-as-code misconfigurations. This is NOT incident response for active cloud compromise (see incident-response) or application vulnerability scanning (see security-pen-testing) — this is about systematic cloud configuration analysis to prevent exploitation.

Table of Contents

• Overview
• Cloud Posture Check Tool
• IAM Policy Analysis
• S3 Exposure Assessment
• Security Group Analysis
• IaC Security Review
• Cloud Provider Coverage Matrix
• Workflows
• Anti-Patterns
• Cross-References

Overview

What This Skill Does

This skill provides the methodology and tooling for cloud security posture management (CSPM) — systematically checking cloud configurations for misconfigurations that create exploitable attack surface. It covers IAM privilege escalation paths, storage public exposure, network over-permissioning, and infrastructure code security.

Distinction from Other Security Skills

Prerequisites

Read access to IAM policy documents, S3 bucket configurations, and security group rules in JSON format. For continuous monitoring, integrate with cloud provider APIs (AWS Config, Azure Policy, GCP Security Command Center).

Cloud Posture Check Tool

The cloud_posture_check.py tool runs three types of checks: iam (privilege escalation), s3 (public access), and sg (network exposure). It auto-detects the check type from the config file structure or accepts explicit --check flags.

# Analyze an IAM policy for privilege escalation paths
python3 scripts/cloud_posture_check.py policy.json --check iam --json

# Assess S3 bucket configuration for public access
python3 scripts/cloud_posture_check.py bucket_config.json --check s3 --json

# Check security group rules for open admin ports
python3 scripts/cloud_posture_check.py sg.json --check sg --json

# Run all checks with internet-facing severity bump
python3 scripts/cloud_posture_check.py config.json --check all \
  --provider aws --severity-modifier internet-facing --json

# Regulated data context (bumps severity by one level for all findings)
python3 scripts/cloud_posture_check.py config.json --check all \
  --severity-modifier regulated-data --json

# Pipe IAM policy from AWS CLI
aws iam get-policy-version --policy-arn arn:aws:iam::123456789012:policy/MyPolicy \
  --version-id v1 | jq '.PolicyVersion.Document' | \
  python3 scripts/cloud_posture_check.py - --check iam --json

Exit Codes

IAM Policy Analysis

IAM analysis detects privilege escalation paths, overprivileged grants, public principal exposure, and data exfiltration risk.

Privilege Escalation Patterns

IAM Finding Severity Guide

Least Privilege Recommendations

For every critical or high finding, the tool outputs a least_privilege_suggestion field with specific remediation guidance:

• Replace Action: * with a named list of required actions
• Replace Resource: * with specific ARN patterns
• Use AWS Access Analyzer to identify actually-used permissions
• Separate dangerous action combinations into different roles with distinct trust policies

S3 Exposure Assessment

S3 assessment checks four dimensions: public access block configuration, bucket ACL, bucket policy principal exposure, and default encryption.

S3 Configuration Check Matrix

Recommended S3 Baseline Configuration

{
  "PublicAccessBlockConfiguration": {
    "BlockPublicAcls": true,
    "BlockPublicPolicy": true,
    "IgnorePublicAcls": true,
    "RestrictPublicBuckets": true
  },
  "ServerSideEncryptionConfiguration": {
    "Rules": [{
      "ApplyServerSideEncryptionByDefault": {
        "SSEAlgorithm": "aws:kms",
        "KMSMasterKeyID": "arn:aws:kms:region:account:key/key-id"
      },
      "BucketKeyEnabled": true
    }]
  },
  "ACL": "private"
}

All four public access block settings must be enabled at both the bucket level and the AWS account level. Account-level settings can be overridden by bucket-level settings if not both enforced.

Security Group Analysis

Security group analysis flags inbound rules that expose admin ports, database ports, or all traffic to internet CIDRs (0.0.0.0/0, ::/0).

Critical Port Exposure Rules

High-Risk Database Port Rules