Exam NetSec-Generalist Topic 3 Question 7 Discussion

In a Zero Trust Architecture (ZTA), network segmentation is critical to prevent unauthorized lateral movement within a flat network. Since the hospital system allows mobile medical imaging trailers to connect directly to its internal network, this poses a significant security risk, as these trailers may introduce malware, vulnerabilities, or unauthorized access to sensitive medical data.
The most cost-effective and practical solution in this scenario is:
Creating separate security zones for the imaging trailers.
Applying access control and inspection policies via the hospital's existing core firewalls instead of deploying new hardware.
Implementing strict policy enforcement to ensure that only authorized communication occurs between the trailers and the hospital's network.
Why Separate Zones with Enforcement is the Best Solution?
Network Segmentation for Zero Trust
By placing the medical imaging trailers in their own firewall-enforced zone, they are isolated from the main hospital network.
This reduces attack surface and prevents an infected trailer from spreading malware to critical hospital systems.
Granular security policies ensure only necessary communications occur between zones.
Cost-Effective Approach
Uses existing core firewalls instead of deploying costly additional edge firewalls at every campus.
Reduces complexity by leveraging the current security infrastructure.
Visibility & Security Enforcement
The firewall enforces security policies, such as allowing only medical imaging protocols while blocking unauthorized traffic.
Integration with Threat Prevention and WildFire ensures that malicious files or traffic anomalies are detected.
Logging and monitoring via Panorama helps the security team track and respond to threats effectively.
Other Answer Choices Analysis
(A) Deploy edge firewalls at each campus entry point
This is an expensive approach, requiring multiple hardware firewalls at every hospital location.
While effective, it is not the most cost-efficient solution when existing core firewalls can enforce the necessary segmentation and policies.
(B) Manually inspect large images like holograms and MRIs
This does not align with Zero Trust principles.
Manual inspection is impractical, as it slows down medical workflows.
Threats do not depend on image size; malware can be embedded in small and large files alike.
(D) Configure access control lists (ACLs) on core switches
ACLs are limited in security enforcement, as they operate at Layer 3/4 and do not provide deep inspection (e.g., malware scanning, user authentication, or Zero Trust enforcement).
Firewalls offer application-layer visibility, which ACLs on switches cannot provide.
Switches do not log and analyze threats like firewalls do.
Reference and Justification:
Firewall Deployment - Firewall-enforced network segmentation is a key practice in Zero Trust.
Security Policies - Granular policies ensure medical imaging traffic is controlled and monitored.
VPN Configurations - If remote trailers are involved, secure VPN access can be enforced within the zones.
Threat Prevention & WildFire - Firewalls can scan imaging files (e.g., DICOM images) for malware.
Panorama - Centralized visibility into all traffic between hospital zones and trailers.
Zero Trust Architectures - This solution follows Zero Trust principles by segmenting untrusted devices and enforcing least privilege access.
Thus, Configuring separate zones (C) is the correct answer, as it provides cost-effective segmentation, Zero Trust enforcement, and security visibility using existing firewall infrastructure.