Unauthorized Access and Social Engineering

A.

The attack described in the question is most likely a vishing attack, option A. Vishing, or voice phishing, is a social engineering attack where an attacker calls the victim over the phone and attempts to trick them into revealing sensitive information, such as usernames and passwords or credit card numbers.

In this scenario, the attacker is posing as a helpdesk representative and claiming that the CEO's computer is broadcasting across the network. The attacker then asks for the CEO's network authentication credentials to verify her identity. This is a common tactic used in vishing attacks to gain access to sensitive information.

Option B, impersonation, is also a type of social engineering attack where an attacker pretends to be someone else, but it is not specific to phone calls. Option C, spim, refers to spam over instant messaging, and option D, scareware, refers to software that tricks users into downloading and installing malware by claiming that their computer is infected with viruses.

Overall, the scenario described in the question is most consistent with a vishing attack, and it is important for the CEO and her organization to be aware of these types of attacks and take steps to protect against them, such as implementing multi-factor authentication and training employees on how to spot and avoid social engineering attacks.