The WannaCry ransomware attack began in Europe and affected hundreds of thousands of machines worldwide across a range of industries, mostly targeting hospitals. This attack raised serious concerns of threats to critical infrastructures. Now the onus falls on critical infrastructures to strengthen their posture against these kinds of attacks. Most cyber threats can be countered or avoided by following basic cybersecurity best practices. This white paper provides a checklist of methods and measures such as vulnerability scanning and patching, application whitelisting andbusiness continuity, among others, with rationales, values and strategy measures. Measures mentioned in this paper can provide effective and proactive countermeasures against cybersecurity threats.