A penetration tester writes the following script, which is designed to hide communication and bypass...

The script is retrieving base64-encoded commands hidden in DNS TXT records and executing them. This is a technique known as DNS tunneling, which allows covert data transmission using DNS queries/responses — often used to bypass firewalls or exfiltrate data without detection.

From the CompTIA PenTest+ PT0-003 Official Study Guide (Chapter 9 – Evading Detection and Exploitation Techniques):

“DNS tunneling is a covert communication technique where command-and-control instructions or exfiltrated data are encoded into DNS queries and responses, typically using TXT records.”