Insider threats represent a critical risk to network security, arising from People who are trusted in a company but abuse their access to damage systems, steal data, or disrupt operations. These threats can originate from malicious actors with intent to damage, negligent employees who inadvertently cause breaches, or compromised insiders coerced into wrongdoing. The challenge of detecting insider threats lies in their legitimate access and deep understanding of organizational systems, often allowing them to bypass traditional security measures. Motivations for such actions vary, including financial gain, revenge, espionage, or ideological beliefs. This paper examines insider threats’ nature, key challenges in detection, and effective mitigation strategies such as behavioural analytics, access controls Endpoint Detection and Response (EDR), and Corporate Insider Threat Detection project (CIDR) and its working in detail.