De acordo com uma resposta neste Post do fórum do Microsoft Answers , é um serviço válido do Windows:
[The] OS Remediation System Service is a [legitimate] service from Microsoft included in [the] KB4056254 update.
A mesma resposta do mesmo Microsoft Agent fornece este suporte oficial da Microsoft link que fornece mais alguns detalhes:
This update includes a background service to facilitate Windows Update service on devices running Home or Pro editions of Windows 10 Versions 1507, 1511, 1607, and 1703.
This update includes files and resources to address issues affecting background update processes in the Windows Update servicing stack. Maintaining Window Update service health and performance helps ensure that quality updates are installed seamlessly on your device and help to improve the reliability and security of devices running Windows 10.