Episode 26 — Test segmentation and controls for credible assurance
Segmentation only reduces PCI scope when it works in practice, and the exam looks for evidence that barriers are effective, not just diagrammed. This episode explains the assurance mindset behind testing: begin from a clear scoping narrative, enumerate CDE entry points, and define expected trust boundaries. From there, map technical controls to test objectives—firewall deny-by-default, ACL pinholes, jump host mediation, and authentication on management paths—and select methods that can prove each objective. Packet captures, ruleset reviews, and routing tables show intended paths, while targeted connectivity tests validate reality. We highlight why sampling matters: pick representative systems from each zone, include shared services like DNS and NTP, and validate that monitoring detects and records blocked attempts. The goal is reproducibility: a third party given your plan and artifacts should reach the same conclusion about isolation strength.
We expand with exam-ready scenarios that contrast strong and weak practices. Strong assurance combines multiple angles: host-based tests that show no reachable ports from non-CDE zones, firewall logs that record denied traversals with timestamps, and documented approvals for every exception. Weak assurance relies on a single nmap run from one source or accepts a verbal claim that “the VLANs are separate.” Troubleshooting guidance addresses common failures such as management networks that quietly bridge zones, “temporary” rules never closed, or bastion hosts that permit lateral movement after login. Credible evidence pairs results with change control: when a rule is added, re-test affected paths and attach proof to the record. On the exam, correct answers pair design intent with methodical verification and artifacts—test plans, outputs, annotated diagrams, and logs—that together demonstrate segmentation is both present and dependable. Produced by BareMetalCyber.com, where you’ll find more cyber audio courses, books, and information to strengthen your educational path. Also, if you want to stay up to date with the latest news, visit DailyCyber.News for a newsletter you can use, and a daily podcast you can commute with.
