An analyst is part of a team that is investigating a potential breach of sensitive data at a large financial services organization. the organization suspects a breach occurred when proprietary data was disclosed to the public. the team finds servers were accessed using shared credentials that have been in place for some time. in addition, the team discovers undocumented firewall rules, which provided unauthorized external access to a server. suspecting the activities of a malicious insider threat, which of the following was most likely to have been utilized to exfiltrate the proprietary data?

keylogger
botnet
cryptomalware
backdoor
ransomware
dlp