Which of the following is a characteristic of vertical privilege escalation?

Vertical privilege escalation refers to the process of obtaining a higher level of permissions than what a user is initially granted. This typically involves gaining unauthorized access to higher privileges, such as administrative rights. In this context, option B reflects the essence of vertical privilege escalation because it specifically describes the act of gaining unauthorized access at a higher privilege level than that of the current user.

In contrast, the other options do not accurately depict vertical privilege escalation. For example, accessing a file server with regular user permissions indicates that the user is operating within their granted level of access rather than escalating it. Sharing credentials involves the distribution of access rights rather than an elevation of privilege. Lastly, while social engineering can be a tactic used to alter privileges, it does not inherently denote vertical privilege escalation, as it could lead to various outcomes that do not involve elevating privileges through unauthorized means.