A penetration tester enters an office building at the same time as a group of employees despite not having an access badge. Which of the following techniques is the tester using?

Piggybacking refers to an authorized person intentionally allowing an unauthorized individual to enter a secure area by holding the door open or giving access. Unlike tailgating, which can occur without the knowledge of the authorized person, piggybacking involves cooperation or consent from the authorized individual, making it a different concept altogether.

Shoulder surfing is a technique used to obtain confidential information by observing someone’s activities, typically when they enter sensitive data like passwords or PINs. This technique does not apply here, as the scenario focuses on physical access to a building rather than the acquisition of information through observation.

Phishing involves tricking individuals into providing sensitive information, often through deceptive emails or websites. This technique is unrelated to physical access and security breaches, making it an unsuitable choice in the context of the penetration tester's entry into the office building.