A failed PCI ASV scan can put you under pressure, particularly when the end of the quarter is approaching. But before working through every failed finding one by one, it’s worth understanding what the report is telling you.

From helping organizations work through failed ASV scans, we know that the report can often look more complicated than the underlying problem. Several failed findings may trace back to the same outdated component or configuration, while others may need further investigation before you determine whether remediation is required.

The fastest route to a passing scan usually starts with diagnosing the failure, rather than simply trying to clear the report. From there, you can decide what needs to be fixed, what needs to be verified and, where appropriate, what may need to be disputed with your ASV.

First – Why Did Your ASV Scan Fail?

Your PCI ASV scan will fail if the scanner identifies any vulnerabilities with a CVSS score of 4.0 or higher. The requirements also define automatic failure conditions for some software and configurations, such as an unsupported internet-facing operating system.

An ASV assesses what is visible externally. Internal records saying a patch was installed are not enough if the vulnerable service still presents itself to the scanner. For instance:

• A patch was installed but the service wasn’t restarted.
• The configuration was changed on the wrong host or environment.
• A load balanced node was missed.
• A firewall or security group change was approved but not deployed.
• An old appliance or service was still reachable from another IP.
• The system uses backporting and shows older versions than what is actually in use. In this case providing the patch version in a dispute resolves the matter.

Fixing an issue only counts as completed for PCI ASV scanning purposes when the external exposure has changed or evidence of remediation has been validated.

What Should You Do? Working Through a Failed ASV Scan

Once you understand what caused the scan to fail, the next job is to turn the report into a manageable remediation plan. A simple way to do that is to work through the findings in five steps:

Step 1: Review the Report

Start with the findings and the evidence behind them. Check the affected IP addresses, ports, services and detected software, and look for patterns that could point to a common cause. The aim at this stage is to understand what the scanner found and why it failed, rather than jumping straight into remediation. Note that many findings contain “information gathered” which detail the test conditions that led to a failure; validating against the wrong endpoints is a common cause for misunderstandings.

Step 2: Sort into Fixes and Disputes

If the vulnerability is genuinely present and exposed, it belongs in the remediation pile. If there is good reason to believe the scanner has identified the wrong product or version, the vulnerability does not apply, or another technical factor has affected the result, it may be something to raise with your ASV.

Step 3: Remediate Genuine Findings

Most ASV failures tend to come back to a relatively small number of problems:

• Outdated software.
• Weak configurations.
• Unnecessary internet exposure.
• Forgotten systems.

Remediation typically means patching or upgrading software, changing a configuration, removing an unnecessary internet-facing service or replacing an unsupported component. Once you have applied the fix, perform a rescan to validate the changes.

Another way for remediation is validating what systems even need to be accessible from the internet and which ones can be protected by firewalling or ACLs, reducing the attack surface of the CDE. They must still be remediated as part of the internal vulnerability management processes which are also part of the PCI DSS requirements, but a reduced attack surface is always an enhancement to security.

Step 4: Dispute Incorrect or Inaccurate Findings

If you believe a finding is incorrect or does not apply, gather the technical evidence needed to support that position and raise it with your ASV. Remember that the dispute process exists to correct or clarify a finding, not to avoid remediation because a fix is difficult or inconvenient. If a vulnerability is present and the system is genuinely exposed, the right response is normally to remediate it.

Step 5: Run the Rescan

Once the genuine vulnerabilities have been remediated and any disputes have been resolved, run the ASV scan again. Ideally, the rescan should confirm the work you have already done rather than tell you whether the fixes worked. If a finding remains, go back to the evidence and investigate why. For instance, the change might not have reached every affected system.

What Should You Fix First?

When looking at several vulnerabilities to remediate, it can be tempting to start at the highest CVSS score and work your way down. While CVSS is useful for prioritization, the real risk to your systems also depends on how exposed the service is, whether the issue can be exploited remotely, what the affected system does, and whether there are known exploits in use.

For ASV remediation, a sensible order is to focus first on:

• The highest-risk internet-facing vulnerabilities: Prioritize issues that could be exploited remotely, especially where authentication is not required or the affected service is directly exposed to the internet.
• Findings that automatically prevent a passing scan: Some ASV failures are triggered by specific conditions, such as unsupported software or insecure configurations, regardless of the CVSS score.
• Root causes that affect several findings: If one outdated component is responsible for multiple vulnerabilities, fixing that component could remove several failures at once.
• Issues that will take longest to remediate: Unsupported systems, appliance upgrades or changes that require maintenance windows can easily hold up a rescan, so it makes sense to start these early.

The key point is not to work through the report from top to bottom or simply chase the highest CVSS number first. Use severity to understand risk, but combine it with exploitability, exposure, scope and the effort needed to make the change.

Remember that prioritization only decides what you fix first. You still need to remediate every genuine finding that prevents the ASV scan from passing before you can achieve a passing result.

When Should You Dispute an ASV Finding?

A dispute usually makes sense when you have good technical reasons to believe the scanner’s conclusion is wrong or incomplete. Some of the common reasons for a dispute include:

• False positives: The scanner detected a vulnerability that either doesn’t exist or doesn’t apply to your environment.
• Scope errors: The scanner identified issues in systems that weren’t meant to be scanned.
• Compensating controls: Security measures are in place to manage the vulnerability and mitigate risk to the CDE. Note that a compensating control must address the vulnerability and can also not be another standard control.

You’ll need evidence of why the findings are wrong, such as screenshots or vendor documentation or statements verifiable by the ASV. The ASV is responsible for reviewing the evidence and deciding whether it’s sufficient to resolve the finding.

Make PCI Compliance Easier to Manage with Outpost24

A failed PCI ASV scan doesn’t have to derail your compliance program. By understanding why the scan failed, and working methodically through remediation and disputes, you can address any issues and get back on track. With Outpost24’s solutions, you work the remediation and dispute resolutions processes directly online with interactions with our certified staff who review and validate dispute resolution and can provide advice on remediation.

Outpost24 helps organizations protect cardholder data and prove compliance with flexible PCI compliance packages designed around your needs. You can tailor your package with PCI ASV scanning, internal vulnerability assessments, and penetration testing necessary to meet your obligations and only pay for what you need, driving value and operational efficiency.

Schedule scans around your requirements, track findings and remediation in one place, and generate clear, audit-ready reports when you need them. With your PCI testing and reporting easier to manage, your team can spend less time on administration and more time addressing the issues that matter.

If you’re interested in seeing how Outpost24 can help you meet and maintain PCI compliance, contact us today or book a demo to see our solutions in action.