The best first step is to reviewpatching (A). Outdated OS versions often contain vulnerabilities that can be exploited by malware. Ensuring systems are up-to-date is a foundational cybersecurity practice. This is highlighted inDomain 2.1: Given a scenario, analyze indicators of malicious activityandDomain 2.2, emphasizing the importance of"Patching" as part of system hardening and mitigation strategy. Reference: CompTIA Security+ SY0-701 Objectives, Domain 2.2 - "Mitigation techniques: Patching."