With the advancement of informatization, the economic, political, and national life have become increasingly dependent on network information systems, making network information security issues a prominent concern for national and social security. Driven by economic or political interests, the competition among enterprises, institutions, and even governments in the cyberspace are continuously intensifying. Network attacks characterized by high technology, high concealment, and long duration have become one of the main challenges facing current network security. The article introduces and describes this type of covert network attack, analyzes its main features and security challenges, and reviews the latest research findings on the detection of covert network attacks at home and abroad. Finally, it summarizes the key technical issues and looks forward to the future research directions in this field.