Industry 4.0 is a blend of the hyper-connected digital industry within two world of Information Technology (IT) and Operational Technology (OT). With this amalgamate opportunity, smart manufacturing involves production assets with the manufacturing equipment having its own intelligence, while the system-wide intelligence is provided by the cyber layer. However Smart manufacturing now becomes one of the prime targets of cyber threats due to vulnerabilities in the existing process of operation. Since smart manufacturing covers a vast area of production industries from cyber physical system to additive manufacturing, to autonomous vehicles, to cloud based IIoT (Industrial IoT), to robotic production, cyber threat stands out with this regard questioning about how to connect manufacturing resources by network, how to integrate a whole process chain for a factory production etc. Cybersecurity confidentiality, integrity and availability expose their essential existence for the proper operational thread model known as digital thread ensuring secure manufacturing. In this work, a literature survey is presented from the existing threat models, attack vectors and future challenges over the digital thread of smart manufacturing.

翻译：工业4.0是信息技术（IT）与操作技术（OT）两个世界高度互联数字产业的融合。借助这一融合机遇，智能制造涉及具有自身智能的生产资产与制造设备，而系统级智能则由网络层提供。然而，由于现有操作流程中的脆弱性，智能制造现已成为网络威胁的主要目标之一。由于智能制造涵盖从信息物理系统到增材制造、自动驾驶汽车、基于云的工业物联网（IIoT）、机器人生产等广泛的生产工业领域，网络威胁在此背景下尤为突出，提出了如何通过网络连接制造资源、如何整合工厂生产的完整流程链等问题。网络安全的机密性、完整性、可用性在确保安全制造的数字线程这一操作威胁模型中展现了其核心作用。本文对现有威胁模型、攻击向量及智能制造数字线程的未来挑战进行了文献综述。