With the release of PCI DSS 4.0, penetration testing requirements have become more rigorous. The scope has expanded to ensure comprehensive security coverage within the Cardholder Data Environment (CDE) and beyond. The enhanced scope now mandates deeper assessments, covering not just the primary CDE but also any connected systems that could impact its security.
In this blog, we’ll discuss the expanded penetration testing scope under PCI DSS 4.0, what it means for businesses handling cardholder data, and how organizations can effectively meet these new requirements.
Expanded Scope: Full Coverage of the CDE and Beyond
1. All Components Within the CDE Are In Scope
Under PCI DSS 4.0, penetration testing must cover every system and network component that stores, processes, or transmits cardholder data. This means businesses must assess servers, databases, workstations, network devices, and endpoints within the CDE.
No system is exempt—every device and application interacting with cardholder data must be tested to uncover vulnerabilities before attackers can exploit them.
2. Connected Systems Are Now Included
One of the most significant changes in PCI DSS 4.0 is the requirement to extend penetration testing beyond the CDE. Any system or network that connects to, interacts with, or could impact the security of the CDE is now part of the testing scope.
This means businesses must evaluate:
- Third-party systems that access or integrate with the CDE
- Partner networks that exchange payment-related information
- Cloud environments that store or process cardholder data
- Internal IT infrastructure that could be leveraged in an attack against the CDE
This expanded requirement ensures that potential attack paths leading to the CDE are identified and mitigated before they can be exploited.
Authentication and Access Control Testing
1. Strengthened Multi-Factor Authentication Validation
With multi-factor authentication (MFA) now a mandatory requirement under PCI DSS 4.0, penetration tests must verify that MFA implementations are effective and cannot be bypassed. This involves testing:
- MFA login mechanisms for vulnerabilities, such as session hijacking or replay attacks
- The robustness of password and access policies
- Protection against brute-force attacks and credential stuffing
Ensuring that authentication methods are resistant to real-world attack scenarios is crucial for securing cardholder data.
2. Testing Access Controls at Every Entry Point
Access control testing has also been strengthened under PCI DSS 4.0. Businesses must evaluate all access points to the CDE, ensuring that:
- Least privilege principles are enforced for all users
- Privileged accounts are secured and monitored
- Unauthorized users cannot escalate privileges
- Session management controls prevent unauthorized access
Penetration testing must validate that only authorized users can access sensitive systems, reducing the risk of insider threats and external attacks.
Network Segmentation Testing: Proving It Works
1. Verifying Effective Isolation of Cardholder Data
For organizations using network segmentation to separate the CDE from other systems, PCI DSS 4.0 requires penetration testing to confirm its effectiveness. The goal is to block unauthorized access, preventing attackers from moving laterally into the CDE.
Testing must:
- Verify that segmentation controls are properly implemented
- Simulate attack scenarios to confirm that unauthorized access is blocked
- Assess firewall configurations and ACL rules for misconfigurations
- Ensure that breaches in other network areas do not compromise cardholder data
2. Preventing Lateral Movement
An attacker who gains access to a non-CDE system should be unable to pivot into the CDE. Testing must validate that segmentation controls prevent:
- Unauthorized access to payment processing systems
- Lateral movement across internal networks
- Data exfiltration routes between segmented environments
Businesses can reduce the risk of network-wide breaches by ensuring that segmentation barriers remain impenetrable.
Why the Expanded Testing Scope Matters
The changes in PCI DSS 4.0 reflect the evolving cybersecurity landscape. Attackers are no longer just targeting primary CDE systems—they exploit weaker connected networks and third-party integrations to gain access.
- By expanding penetration testing requirements, PCI DSS 4.0 ensures that businesses:
- Uncover hidden vulnerabilities across all interconnected systems
- Prevent attackers from bypassing weak access controls
- Strengthen network segmentation to isolate critical assets
- Validate security controls with real-world attack simulations
- Reduce compliance risks and avoid costly data breaches
How to Ensure Compliance with PCI DSS 4.0’s Expanded Penetration Testing Scope
Meeting the new penetration testing requirements requires a strategic, well-planned approach. Here’s how businesses can stay compliant:
1. Work with Experienced Penetration Testing Providers
Partnering with qualified security professionals ensures that tests are performed thoroughly and meet PCI DSS 4.0 standards.
2. Conduct Regular Testing Beyond Annual Assessments
Instead of relying on a once-a-year test, businesses should implement continuous penetration testing to address evolving threats.
3. Evaluate Third-Party and Cloud Connections
Ensure that any external system connected to the CDE undergoes penetration testing to prevent supply chain attacks.
4. Test MFA and Access Controls Rigorously
Confirm that authentication methods cannot be bypassed and that user access policies follow best practices.
5. Verify Network Segmentation Regularly
Segmentation testing should be performed after any infrastructure change to confirm that CDE isolation remains intact.
Final Thoughts
With PCI DSS 4.0, penetration testing has evolved into a comprehensive, in-depth security assessment covering all systems linked to cardholder data. Businesses must go beyond checking off compliance requirements and adopt a proactive security approach to protect against real-world cyber threats.
By embracing the Enhanced Testing Scope, organizations can strengthen their security posture, prevent data breaches, and ensure compliance with PCI DSS 4.0’s stricter requirements.
Need Expert PCI DSS Penetration Testing?
At MainNerve, we specialize in comprehensive penetration testing, security assessments, and PCI compliance. Our team ensures your organization meets PCI DSS 4.0 standards while safeguarding your cardholder data from emerging threats.
Contact us today to schedule your PCI DSS 4.0 penetration test!
