Gather Victim Network Information

Adversaries may gather information about the victim’s networks that can be used during targeting. Information about networks may include a variety of details, including administrative data (ex: IP ranges, domain names, etc.) as well as specifics regarding its topology and operations.

Adversaries may gather this information in various ways, such as direct collection actions via Active Scanning or Phishing for Information. Information about networks may also be exposed to adversaries via online or other accessible data sets (ex: Search Open Technical Databases).[1][2][3] Gathering this information may reveal opportunities for other forms of reconnaissance (ex: Active Scanning or Search Open Websites/Domains), establishing operational resources (ex: Acquire Infrastructure or Compromise Infrastructure), and/or initial access (ex: Trusted Relationship).

Source:
https://attack.mitre.org/techniques/T1590