Which of the following is a method used to bypass normal security and authentication functions?

The chosen answer identifies backdoors as a method used to bypass normal security and authentication functions. A backdoor is an intentional entrance left in a software system that allows for unauthorized access to data or system functions without going through the usual security mechanisms. This can be implemented by software developers for maintenance purposes, but it can also be exploited by malicious actors to gain access to systems without going through the standard authentication processes.

Understanding backdoors is crucial because they present a significant security risk. Once in place, they can allow attackers to circumvent security measures, making it easier for them to manipulate systems, steal data, or install additional malicious software. This is why recognizing and securing any potential backdoor is vital in a security strategy.

In contrast, other options like phishing and social engineering involve manipulating individuals to gain access or information, rather than exploiting a technical flaw or opening like a backdoor. Credential stuffing, on the other hand, involves using stolen credentials from one service to gain access to another service due to users reusing passwords, which, while problematic, does not inherently bypass security and authentication functions in the way a backdoor does.