Answer:
D. Data exfiltration
Step-by-step explanation:
Data theft can be defined as a cyber attack which typically involves an unauthorized access to a user's data with the sole intention to use for fraudulent purposes or illegal operations. There are several methods used by cyber criminals or hackers to obtain user data and these includes DDOS attack, SQL injection, man in the middle, phishing, sniffing, data exfiltration, etc.
The type of attack in this scenario is best described as data exfiltration.
Data exfiltration can be defined as a form of data security breach that typically involves an unauthorized transfer of data from a host computer by using a malware and a malicious code.
Hence, data exfiltration occurs when a malicious code uses a domain name server (DNS) as a tunnel to extract data from an end user's computer (client machine) and transferring it to an unsecure public Internet site.