Zero Trust Networking in AWS

Zero Trust Networking in AWS

Zero Trust eliminates implicit trust based on network location. Instead of "trust everything inside the VPC," Zero Trust requires continuous verification of every request. This approach is essential for modern cloud architectures where the perimeter is everywhere.

Zero Trust Principles

1. Never trust, always verify — Every request must be authenticated and authorized regardless of source
2. Assume breach — Design as if attackers are already inside your network
3. Least privilege access — Grant minimum permissions required for each operation
4. Microsegmentation — Isolate workloads at the finest granularity possible

Identity-Based Access

Replace IP-based rules with identity-based policies:

# Traditional (IP-based)
Security Group: Allow 10.0.10.0/24 → port 5432

# Zero Trust (identity-based)
IAM Policy: Allow role/api-service → RDS connection
VPC Endpoint: Private access only
Security Group: Allow sg-api-service → port 5432

Microsegmentation with Security Groups

# Each service gets its own Security Group
# Rules reference Security Group IDs, not CIDRs

# API Service SG
Inbound: Allow TCP 8080 from sg-alb (load balancer)
Outbound: Allow TCP 5432 to sg-database

# Database SG
Inbound: Allow TCP 5432 from sg-api-service ONLY
Outbound: None

# Cache SG
Inbound: Allow TCP 6379 from sg-api-service ONLY
Outbound: None

AWS Verified Access

AWS Verified Access provides Zero Trust access to applications without VPN:

# Users authenticate via SSO
# Access policies evaluate identity + device posture + context
# No VPN needed — works over HTTPS

aws verified-access-trust-provider create \
  --trust-provider-type user \
  --user-trust-provider-type iam-identity-center

aws verified-access-group create \
  --verified-access-instance-id vai-xxx \
  --policy-document '{
    "Version": "2012-10-17",
    "Statement": [{
      "Effect": "Allow",
      "Principal": "*",
      "Action": "ec2:*",
      "Condition": {
        "StringEquals": {
          "aws:PrincipalTag/department": "engineering"
        }
      }
    }]
  }'

Network Segmentation Architecture

Internet → CloudFront (WAF) → ALB → API Service → Database
                                         ↓
                                    Cache Service
                                         ↓
                                    Queue Service

Each arrow = explicit Security Group rule
No lateral movement possible between services
All internal traffic over TLS

Implementing Zero Trust Step by Step

Eazy SaaS Tip: We implement Zero Trust incrementally — starting with microsegmentation (Security Groups referencing SG IDs) and identity-based access (IAM roles per service). This gives 80% of the security benefit without the complexity of a full service mesh.