ECS is a voluntary program based on the sharing of indicators of malicious cyber activity between DHS and participating Commercial Service Providers.  The program assists owners and operators of critical infrastructure to enhance the protection of their systems from unauthorized access, exploitation, or data exfiltration through a voluntary information sharing program.  ECS consists of the operational processes and security oversight required to share unclassified and classified cyber threat indicators with companies that provide internet, network, and communication services to enable those companies to enhance their services to protect U.S. Critical Infrastructure entities. ECS is intended to support U.S. Critical Infrastructure, however, pending deployment of EINSTEIN intrusion prevention capabilities, ECS may also be used to provide equivalent protection to participating Federal civilian Executive Branch agencies.  NPPD conducted this PIA because PII may be collected.