CISA released Barriers to Secure OT Communication guidance to highlight known issues associated with insecure-by-design legacy industrial protocols and examines why technologies that can secure these protocols are not widely adopted. The guidance notes that legacy OT protocols lack strong protections against data alteration, device impersonation, and unauthorized access, which can leave critical infrastructure vulnerable to cyber threats. CISA provides recommendations to help owners and operators avoid negative experiences reported by peers and offers recommendations to OT manufacturers to promote more sustainable and usable security capabilities.