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First-Seen Detection

A SIEM detection technique that flags activity occurring for the first time in an environment, a new domain, a never-before-seen process, a first login from a location, since novelty often signals something worth investigating.

First-seen detection compares current activity against historical baselines to surface things that have never appeared before: a host contacting a brand-new domain, an account logging in from a new country, an unfamiliar binary executing. Novelty is a useful signal because attacker infrastructure and tools are often new to the environment. Built as SIEM queries against a baseline, it complements known-bad detection by catching the previously unseen.

Introduced in: SIEM Query Fundamentals

Examples

  • Flagging the first time a host connects to a particular external domain.
  • Alerting on a never-before-seen process executing in the environment.
  • Detecting a first login from a new country for an account.

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