Which of the following describes passive reconnaissance?

• A. Brute-forcing credentials against a login portal.
• B. Exploiting vulnerabilities to gain access.
• C. Scanning target ports to enumerate open services.
• D. Gathering information from public sources without contacting the target.

Answer: (D)

Passive reconnaissance is about gathering information about a target without directly interacting with it. It relies on data that’s publicly available, such as company websites, social media, press releases, public records, domain registration data, and archived sources. Because there’s no direct contact with the target’s systems or networks, this approach remains stealthy and less detectable. This contrasts with methods that involve interacting with the target: brute-forcing credentials attempts to log into a portal, exploiting vulnerabilities to gain access, and scanning target ports to enumerate open services—all of which involve active probing or attempts that can trigger defenses. Therefore, collecting information from public sources without contacting the target best describes passive reconnaissance.