Securing cloud infrastructure requires a fundamentally different approach than traditional on-premises security. This guide provides a comprehensive framework for designing security into cloud deployments across AWS, Azure, and Google Cloud Platform.

Core Principles

1. Assume Breach

Design your architecture assuming attackers will gain access to some component. Implement:

Network segmentation and micro-segmentation
Least privilege access at every layer
Encryption for data at rest and in transit
Comprehensive logging and monitoring

2. Defense in Depth

Layer multiple security controls so that failure of any single control doesn’t result in compromise:

Perimeter controls (WAF, DDoS protection)
Network controls (security groups, NACLs)
Identity controls (IAM, MFA)
Application controls (input validation, secrets management)
Data controls (encryption, classification)

3. Shift Left

Integrate security into the development process rather than bolting it on after deployment:

Infrastructure as Code security scanning
Container image scanning in CI/CD
Secrets detection in source control
Security requirements in user stories

Identity and Access Management

Identity is the new perimeter in cloud environments. Implement:

Centralized Identity

Use a single identity provider for all cloud accounts:

Azure AD / Entra ID for Microsoft environments
AWS IAM Identity Center (formerly SSO)
Google Cloud Identity
Third-party solutions like Okta or Ping

Role-Based Access Control

Define roles based on job functions, not individuals:

# Example AWS IAM policy for read-only security auditor
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "securityhub:Get*",
        "securityhub:List*",
        "guardduty:Get*",
        "guardduty:List*"
      ],
      "Resource": "*"
    }
  ]
}

Enforce MFA Everywhere

Require multi-factor authentication for:

Console access
CLI/API access for privileged operations
Service account access to sensitive resources

Network Security

Virtual Network Design

Segment your network into tiers:

Public tier: Load balancers, bastion hosts
Application tier: Web servers, application servers
Data tier: Databases, storage
Management tier: Monitoring, logging, security tools

Private Connectivity

Keep traffic off the public internet:

VPC peering for inter-VPC communication
Private endpoints for cloud services (AWS PrivateLink, Azure Private Link)
Transit gateways for hub-and-spoke topology

Egress Filtering

Control and inspect outbound traffic:

NAT gateways with logging
Proxy servers for internet-bound traffic
DNS filtering for malicious domains

Data Protection

Encryption

Encrypt everything:

At rest: Use cloud-native encryption with customer-managed keys (CMK)
In transit: TLS 1.3 minimum, no legacy protocols
In use: Consider confidential computing for sensitive workloads

Data Classification

Implement a classification scheme:

Level	Examples	Controls
Public	Marketing content	Basic access controls
Internal	Business documents	Authentication required
Confidential	Customer data, PII	Encryption, access logging
Restricted	Credentials, keys	HSM storage, strict access

Data Loss Prevention

Deploy DLP controls:

Cloud-native DLP (AWS Macie, Azure Purview)
Network DLP for egress inspection
Endpoint DLP for downloads

Workload Security

Compute Hardening

Secure your compute instances:

Use hardened, minimal base images
Enable host-based firewalls
Deploy EDR/XDR agents
Implement immutable infrastructure

Container Security

For containerized workloads:

Scan images in CI/CD and registries
Use distroless or minimal base images
Implement pod security standards
Deploy runtime protection

Serverless Security

For functions and managed services:

Minimize function permissions
Validate and sanitize inputs
Use secrets management services
Enable function-level logging

Detection and Response

Security Monitoring

Centralize security telemetry:

Cloud-native SIEM (AWS Security Lake, Azure Sentinel, Chronicle)
Custom detections for your environment
Correlation across identity, network, and workload events

Incident Response

Prepare for incidents:

Document runbooks for common scenarios
Enable automated containment (isolate instances, revoke credentials)
Practice regularly with tabletop exercises

Compliance and Governance

Policy as Code

Enforce compliance automatically:

AWS Config rules, Azure Policy, GCP Organization Policies
Open Policy Agent for Kubernetes
Custom policies for organization-specific requirements

Continuous Compliance

Monitor compliance posture continuously:

CSPM tools for configuration assessment
Automated remediation for drift
Regular compliance reporting

Getting Started

Assess your current cloud security posture
Prioritize gaps based on risk
Implement foundational controls (identity, encryption, logging)
Layer additional controls iteratively
Test and validate continuously