Port Scans: Identifying Open Doors in Your Perimeter

Port scanning is one of the first steps an attacker takes, and it should be one of the first controls your security team masters. By probing internet-facing systems, we can see exactly which services are exposed and whether they match what your architecture and policies expect.

What the Scan Revealed

During a recent assessment, a targeted port scan against your public IP ranges highlighted several weaknesses:

• Exposed admin interfaces that should only be reachable from inside the network

• Legacy services (HTTP, old VPN gateways) still listening on the internet

• Databases and APIs reachable directly, without a reverse proxy or WAF

• Inconsistent firewall rules between sites, leaving some locations far more exposed than others

Each of these findings represents a potential initial foothold for an attacker or ransomware operator.

Why This Matters for Healthcare Environments

In hospitals and clinics, an exposed service is not just a technical issue, it can impact clinical operations and patient data. Internet-facing systems often connect back to EHRs, imaging platforms, labs, or identity providers. A compromise there can cascade into downtime, data theft, and regulatory exposure (HIPAA, GDPR, etc.).

Recommended Actions

To strengthen the perimeter, we typically advise:

• Maintaining a continuously updated inventory of all internet-facing hosts and services

• Standardising firewall policies and default-deny rules across all sites and vendors

• Placing administrative interfaces behind VPN, SSO and strong MFA

• Decommissioning or isolating legacy services that cannot be fully secured

• Scheduling recurring authenticated port scans as part of your routine vulnerability management

Port scans are simple, but they are one of the most reliable ways to verify that your perimeter reflects your security intentions, not just your network diagrams.