Cloud Attack Surface Review for AWS/GCP

The cloud perimeter is not defined by firewalls and subnets; it is defined by identities, APIs, and access policies. Traditional network penetration testing methodologies fail in the cloud because they treat AWS and GCP like data centers. Threat actors don’t break into cloud environments by dropping a 0-day against a load balancer; they compromise an over-privileged developer’s access key, assume a role, and silently exfiltrate an S3 bucket.

This Cloud Attack Surface Review is an intelligence-driven assessment designed for modern infrastructure. It evaluates your AWS and GCP environments through the lens of an attacker, focusing on identity boundaries, exposed assets, CI/CD pipeline vulnerabilities, and the specific control gaps that lead to cloud-native breaches.

The New Perimeter: Identity and Infrastructure as Code

In AWS and GCP, identity is the ultimate attack surface. A misconfigured IAM role attached to an EC2 instance or a Kubernetes pod can grant an attacker full administrative control over an entire organization.

Drawing from extensive incident response and threat hunting experience, this review prioritizes the vectors that actually lead to compromise:

• Identity Sprawl: Evaluating over-privileged users, dormant service accounts, and complex cross-account trust relationships.
• Storage Exposure: Identifying public S3 buckets, misconfigured GCP Cloud Storage ACLs, and unencrypted EBS snapshots.
• CI/CD Integration Risks: Analyzing GitHub Actions runners, hardcoded secrets, and overly permissive deployment roles.
• Network & Edge: Reviewing Security Groups, VPC peering, exposed Kubernetes NodePorts, and Cloudflare WAF bypasses.

Assessment Domains & Methodology

The assessment is conducted via a “white-box” approach, utilizing read-only organizational access to map the true extent of the attack surface safely and comprehensively.

1. Asset Inventory & Exposure Mapping: Discovering all active regions, VPCs, API Gateways, Load Balancers, and rogue public IPs.
2. IAM & Privilege Escalation Review: Analyzing IAM policies for dangerous permissions (iam:PassRole, sts:AssumeRole), lack of MFA, and evaluating the blast radius of compromised credentials.
3. Compute & Workload Analysis: Assessing baseline security for EC2, Compute Engine, Docker container registries, and basic Kubernetes (EKS/GKE) cluster configurations.
4. Data Perimeter Validation: Auditing resource-based policies on S3 buckets, KMS keys, and RDS/Cloud SQL instances to ensure data cannot be accessed externally.
5. Detection & Telemetry Audit: Validating that AWS CloudTrail, VPC Flow Logs, and GCP Audit Logs are enabled, centralized, and immutable, ensuring your SIEM has the necessary visibility to hunt threats.

The Practitioner Tool Stack

We utilize a combination of cloud-native APIs, industry-standard auditing tools, and custom scripting to extract and analyze configuration data:

• Cloud CLIs: AWS CLI, Google Cloud CLI (gcloud)
• Posture Management (CSPM): Prowler, ScoutSuite, Steampipe
• Identity Analysis: Cloudsplaining, custom IAM graphing scripts
• Exposure Validation: Shodan, Nmap (for authorized public endpoints)
• Pipeline Security: GitHub secret scanning tools, TruffleHog

Deliverables & Actionable Intelligence

The output of this review is not a generic dump of compliance failures. It is a prioritized risk register designed for engineering and DevOps teams to execute against.

• Cloud Attack Surface Map: A visual and technical inventory of all externally exposed assets and complex cross-account trust paths.
• IAM Risk Register: A detailed list of over-privileged users, roles, and service accounts, prioritized by their potential for privilege escalation.
• Exposed Asset & Storage Report: Specific findings related to public buckets, open security groups, and exposed APIs.
• CI/CD Risk Notes: Actionable feedback on secure secret management and pipeline hardening.
• Remediation Roadmap: Cloud-native fixes mapping directly to CIS Benchmarks and supporting ISO/IEC 27001 awareness (specifically Access Control and Asset Management clauses).

Typical Cloud Risk Matrix

Risk Priority	Control Gap / Finding	Attack Vector & Business Impact	Remediation Owner
Critical	Over-privileged EC2 Instance Profile	An SSRF vulnerability in a web app could allow an attacker to query the metadata service, retrieve credentials, and assume an AdministratorAccess role.	DevOps / IAM Admin
High	Publicly Writable S3 Bucket	Misconfigured bucket ACLs allow unauthenticated users to overwrite deployment artifacts, leading to potential supply chain compromise.	Cloud Engineering
Medium	Hardcoded AWS Keys in GitHub	Long-lived access keys found in a legacy repository; while inactive, they pose a severe risk if the repository is made public or compromised.	SecOps / Dev Team
Low	Missing CloudTrail Log Encryption	CloudTrail logs are collected but not encrypted at rest via KMS, marginally increasing the risk of log tampering.	Security Engineering

The 45-Day Improvement Plan

To ensure the assessment translates into tangible security posture improvements, we recommend a phased 45-day remediation cycle:

• Days 1-7 (Containment): Address Critical and High-severity exposure immediately. Lock down public S3 buckets, revoke overly permissive IAM roles attached to public-facing compute, and remove hardcoded secrets from source code.
• Days 8-20 (Identity Right-Sizing): Implement least-privilege policies. Transition from long-lived access keys to temporary STS tokens. Enforce MFA for all console and programmatic access.
• Days 21-30 (Network & Edge Hardening): Review and restrict Security Groups. Implement strict egress filtering. Ensure all public traffic routes through Cloudflare or native cloud WAFs.
• Days 31-45 (Detection Engineering): Ensure all CloudTrail and GCP Audit Logs are forwarding to the centralized SIEM. Build out basic threat hunting queries to monitor for AssumeRole anomalies and mass data access events.

Securing the cloud requires understanding how modern infrastructure is built, deployed, and ultimately targeted. This review provides the visibility necessary to harden your environments against the specific tactics utilized by today’s cloud-focused threat actors.