PCI Scoping in Hybrid Cloud Environments

PCI DSS version 4.0 puts fresh attention on scoping through Requirement 12.5.2.
You now need a formal scoping exercise at least once a year and after major changes, and you have to be able to explain and defend it.

That is hard enough in a simple on premises setup.
In a hybrid world with cloud services, shared tools, and legacy systems, it can feel messy and unclear.

A lot of guidance still talks about “on prem only” or “cloud only.”
Hybrid teams are left in the middle trying to stitch together their own approach.

This post shares a cleaner way to think about PCI scoping in hybrid environments and points you to a GitHub project with templates and worksheets you can start using right away.

👉 GitHub project: PCI Scoping Guide
https://github.com/machine230/pci-scoping-guide

Why Scoping Matters

Scoping is the starting line for every PCI program.
If you get scope wrong, everything that follows is built on a weak foundation.

In PCI DSS 4.0, several requirements connect directly to scoping:

  • 12.5.2 – Do a formal scoping exercise and keep it documented
  • 1.1.3 – Map where cardholder data flows through your environment
  • 1.2.3 – Define and test segmentation controls

Put simply, scope defines:

  • Which systems are in, which are out, and why
  • Which data paths you have to protect and prove
  • Which controls you must design, run, and show evidence for

Good scoping gives you a story that holds up with engineers, leaders, and your QSA.

Common Hybrid Scoping Problems

Hybrid environments tend to trip teams in the same ways.

1. Data flows are unclear

Cardholder data might pass through:

  • On prem apps and databases
  • Cloud APIs and managed services
  • Gateways, message queues, and event buses

If those paths are not mapped, scope turns into guesswork and “tribal knowledge.” That slows down design decisions and the assessment.

2. Scope expands through small connections

You plan to keep a system out of scope, but then you find:

  • Shared admin accounts across CDE and non CDE systems
  • Logging tools pulling from both sides of a segment
  • Support tools that can see or change production data

One weak connection can drag entire networks back into scope and surprise you during testing.

3. Documentation does not match reality

Many teams still rely on:

  • Old Visio diagrams
  • Static inventories that never tracked cloud services
  • Network maps that do not show the real data paths

When the QSA arrives, people scramble to explain how things “really work.”

4. Cloud services are a blind spot

Cloud platforms move fast. Teams are not always sure:

  • Which services touch cardholder data
  • Which services only support or monitor the CDE
  • How shared responsibility affects scope decisions

This is even harder when multiple cloud providers sit on top of older on premises systems.

The PCI Scoping Guide Project

To make this easier, I started an open project on GitHub focused on practical scoping in hybrid environments:

👉 PCI Scoping Guide
https://github.com/machine230/pci-scoping-guide

The project includes templates you can copy or fork:

  • System inventory sheet
    Track systems, roles, scope decisions, and owners in one place.

  • Data flow templates
    Map cardholder data paths for Requirement 1.1.3 in a consistent format.

  • Segmentation checklist
    Capture how you separate CDE and non CDE systems and how you test those controls.

  • AWS service scoping guide
    Walk through common cloud services and how they can affect scope.

  • Hybrid decision guide
    Use a simple decision tree to decide if something is in scope, connected, or truly out of scope.

The goal is to give teams a starting point that feels practical, not theoretical.

How To Use This In Your Own Environment

You can adapt the project to where you are right now.

If you are new to PCI scoping

Start small and keep it simple:

  1. Build an inventory
    List all systems and services that store, process, transmit, or support cardholder data.

  2. Map the data flows
    Use the data flow template to show how card data moves from entry to exit.

  3. Apply the hybrid decision guide
    Mark each system as in scope, connected, or out of scope and write down why.

  4. Record the scoping exercise
    Keep your notes, maps, and decisions together as support for Requirement 12.5.2.

If you work mostly in AWS or another cloud

  1. Review the cloud service guide
    Identify which services directly handle payment traffic and which ones support it.

  2. Check shared services
    Look at logging, monitoring, CI/CD, and identity services that touch both CDE and non CDE systems.

  3. Document segmentation controls
    Record security groups, firewall rules, VPC design, and identity controls that separate scoped systems.

  4. Keep evidence handy
    Save test results, config exports, and diagrams you can re use in future assessments.

If your setup is truly hybrid

  1. Find all connection points
    Identify where cloud systems and on premises systems talk to each other.

  2. Trace cardholder data across each link
    Confirm where data actually flows and where it never should.

  3. Validate segmentation
    Test that your network, identity, and access controls match what your diagrams claim.

  4. Update scope as you learn
    When you find new systems or paths, update the inventory and decision log. Do not wait until audit season.

What Makes This Guide Different

A lot of PCI content is written for auditors or tool vendors.
This project is written for people doing the work:

  • GRC engineers who need a clear story and clean records
  • Security engineers who design controls across CDE and non CDE systems
  • Architects who own hybrid platforms and do not want surprises at assessment time

The language stays simple on purpose so legal, security, product, and infrastructure teams can all follow the same story.

What’s Coming Next

Over time, I plan to add:

  • Examples of common “scope drift” patterns
  • Simple checks for segmentation and isolation
  • Sample QSA questions and how to prepare for them
  • Evidence collection hints tied to specific PCI DSS v4.0 requirements

If you want to follow along or contribute, watch or fork the repo:

https://github.com/machine230/pci-scoping-guide

Final Thoughts

Good scoping is not about shrinking the audit list.
It is about seeing your real exposure and writing it down in a way that others can trust.

In hybrid environments, the only way to stay ahead is to:

  • Keep a live inventory
  • Keep data flows current
  • Keep scope decisions documented and clear

The PCI Scoping Guide is one small step toward making that work repeatable.

If you use the templates, find gaps, or have ideas that could help other teams, open an issue or PR on GitHub. I am always interested in learning how other teams handle hybrid PCI scoping in the real world.