Framework - ISO 27001 (Cyber)

A.8.19 restricts software installation on operational systems to prevent drift, reduce attack surface, and maintain license and support compliance. For the exam, distinguish between development/test flexibility and production control: in operational environments, only authorized, vetted software from approved repositories may be installed, with changes governed by documented requests, peer review, and rollback plans. Baselines should define permissible packages, versions, and configurations, enforced by configuration management or MDM. Evidence includes deployment manifests, signed artifacts, and change records tied to assets and owners. Common pitfalls are local admin rights that allow shadow installs, emergency fixes that bypass approval and remain, and unmanaged plugins or browser extensions that introduce risk. Strong practices quarantine or rebuild noncompliant systems, integrate SBOM tracking, and verify that installed software aligns with vulnerability management scopes and patch cadences so that coverage is real, not assumed.

A.8.20 addresses network security, requiring designs and controls that protect information in transit and manage exposure. Candidates should cover segmentation by trust level and function, least-privilege routing and firewall rules, use of secure protocols, and protective services like DNS security, email authentication, and web application firewalls where appropriate. Zero-trust patterns emphasize identity-aware access and continuous verification rather than implicit trust based on location. Monitoring complements prevention through flow logs, intrusion detection, and anomaly detection tuned to expected behaviors. Pitfalls include flat networks that enable lateral movement, legacy cleartext protocols, and complex rules without ownership or recertification. Effective implementations maintain rule life cycles with justification and expiry, test egress controls to prevent data exfiltration, and document provider-managed boundaries in cloud environments, including shared responsibility delineations. Candidates should be ready to explain how installation discipline reduces exploitable code paths while network security constrains blast radius, and how both depend on accurate inventories, change control, and continuous validation to satisfy auditors and real-world resilience goals. 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.