Carry out a comprehensive audit of your existing technology. Use penetration testing, vulnerability scanning, configuration management, and other security auditing tools to find flaws in the system and prioritize fixes. Conduct system hardening assessments against resources using industry standards from NIST, Microsoft, CIS, DISA, etc.
You do not need to harden all of your systems at once. Instead, create a strategy and plan based on risks identified within your technology ecosystem, and use a phased approach to remediate the biggest flaws.
Ensure that you have an automated and comprehensive vulnerability identification and patching system in place.
Ensure your firewall is properly configured and that all rules are regularly audited; secure remote access points and users; block any unused or unneeded open network ports; disable and remove unnecessary protocols and services; implement access lists; encrypt network traffic.
Put all servers in a secure datacenter; never test hardening on production servers; always harden servers before connecting them to the internet or external networks; avoid installing unnecessary software on a server; segregate servers appropriately; ensure superuser and administrative shares are properly set up, and that rights and access are limited in line with the principle of least privilege.
Remove any components or functions you do not need; restrict access to applications based on user roles and context (such as with application control); remove all sample files and default passwords. Application passwords should then be managed via an application password management/privileged password management solution, that enforces password best practices (password rotation, length, etc.). Hardening of applications should also entail inspecting integrations with other applications and systems, and removing, or reducing, unnecessary integration components and privileges.
Create admin restrictions, such as by controlling privileged access, on what users can do in a database; turn on node checking to verify applications and users; encrypt database information—both in transit and at rest; enforce secure passwords; introduce role-based access control (RBAC) privileges; remove unused accounts;
Apply OS updates, service packs, and patches automatically; remove unnecessary drivers, file sharing, libraries, software, services, and functionality; encrypt local storage; tighten registry and other systems permissions; log all activity, errors, and warnings; implement privileged user controls.