CompTIA Security+ Exam Prep

Answer - D - When a program running on a server bypasses authorization, it is obvious that a back door attack is in progress.

Key Takeaway: In a back door attack, a program or service is placed on a server to bypass normal security procedures. A back door is a program that is designed to hide itself inside a target host. It allows the installing user access to the system at a later time without using normal authorization or vulnerability exploitation.