Passing the Internal Scan for PCI DSS 2.0

Merchants subject to Payment Card Industry Data Security Standard (PCI DSS) rules are often blindsided by DSS changes, arrival of new payment technologies, and newly emerging business context. In addition, many organizations still narrowly focus on annual PCI assessment instead of on running an ongoing compliance program. This article will provide insight on the updated PCI DSS requirement, highlighting the need for internal vulnerability scanning ("perform quarterly internal vulnerability scans"), which was less visible in previous versions.

Whether you are facing PCI compliance or if you have been PCI compliant in the past, you may already know what it means to have a passing external scan; it means that a PCI Approved Scanning Vendor (ASV) will perform a vulnerability assessment of your public IP address space according to the guidelines issued by the PCI Security Standards Council (SSC) in the ASV Program Guide. Typically, it also means that your public IP address space does not contain any vulnerabilities with a CVSS score of 4.0 or higher, or that you have compensating controls in place to mitigate any vulnerabilities in your public IP address space.

Internal Vulnerability Assessment

Beginning June 30^th of this year, the PCI SSC is going to require that you also show proof of passing an internal vulnerability assessment. This requirement is detailed in the PCI DSS Requirement #11.2.1/11.2.3, which describes the testing procedures for internal vulnerability assessments. The key aspects of these assessments are that they must be completed quarterly, and after any significant change; the assessments must also be performed by qualified internal or external resources. Lastly, the assessments must document a “passing result.”

To obtain passing results, the PCI DSS references that “all ‘High’ vulnerabilities defined in PCI DSS Requirement #6.2 are resolved.”  The basic requirements are that you are able to perform a vulnerability assessment of your internal IP address space and that you are able to show that your environment does not have any “High” vulnerabilities, which is the subtle change from prior standards.

The purpose of PCI DSS Requirement #6.2 is to define the process by which you identify vulnerabilities that are to be considered “High,”“Medium,” and ”Low.” Specifically, PCI DSS Requirement #6.2 states: “Establish a process to identify and assign a risk ranking to newly discovered security vulnerabilities.” The requirement also includes notes describing how risk rankings should take into consideration industry best practices and other criteria unique to your own environment; this can include CVSS base scores, vendor-supplied patch rankings, and the criticality of the underlying system components themselves.

The key aspect of PCI Requirement #6.2 is that you have a list of vulnerabilities that you (and your organization) have ranked according to your own process. Then you need to leverage these risk rankings in your vulnerability assessment against your internal IP address space. This will allow you to produce a report that shows a passing scan against your internal scope based on the risk rankings of vulnerabilities you have specified.

Quarterly Internal Scans

This brings us back to the requirement for internal scanning. It is important to remember that you need to perform these scans quarterly and after any significant change to your environment. This will mean that you will want to make sure that however you are assigning risk rankings and using risk rankings in concert with your vulnerability assessment tool, it is simple and repeatable. The ability to automatically produce an internal assessment report quarterly and after any change is a critical component of maintaining your PCI compliance.

It is also critical to review your PCI scope, which defines what IP addresses (both internal and external), are involved in the delivery of your payment card infrastructure. You will want to make sure that you can represent this scope in your vulnerability assessment tools to reduce the manual work that can be involved managing scope changes and reporting.

Structured Approach

In conclusion, having a structured approach for dealing with PCI DSS changes, involving relevant stakeholders, evaluating their impact, and planning controls to close the gaps, should be adopted by security teams. This will help make any security program resilient to environmental and regulatory changes and ensure that the organization can maintain PCI compliance.