what is sigma rule

A Sigma rule is a generic signature format used in cybersecurity for the creation and sharing of detection methods across Security Information and Event Management (SIEM) systems. It is an open-source format that standardizes threat-detection practices, making them accessible and reusable regardless of the SIEM platform in use. Sigma rules are written in YAML syntax, which is a human-readable and easy-to-implement format. They can contain a variety of elements, including a title, data or log source, set of conditions, and tags. Sigma rules are used to detect anomalies in log events and identify suspicious activity. They are easily understood, testable, and tunable, and can be deployed across different SIEM products. Sigma rules are useful for security operations teams to implement standardization into the daily tasks of building SIEM queries, managing logs, and threat hunting.