Security administrator John Smith has noticed abnormal amounts of traffic coming from local computers at night. Upon reviewing, he finds that user data have been exfiltrated by an attacker. AV tools are unable to find any malicious software, and the IDS/IPS has not reported on any non-whitelisted programs.
What type of malware did the attacker use to bypass the company's application whitelisting?

A. File-less malware
B. Zero-day malware
C. Phishing malware
D. Logic bomb malware