Answer: Malware infected the Director's machine and used his privileges
Explanation:
Malware simply means malicious software variants, which consists of spyware, viruses, ransomware etc. These can be used by cyberattackers to cause damage to data or in order to have access to a network.
With regards to the question, Xander believed that malware infected the Director's machine and used his privileges which results in the corrupt of the files.