A well-known organization has been experiencing attacks from APTs. The organization is concerned that
custom malware is being created and emailed into the company or installed on USB sticks that are dropped in
parking lots. Which of the following is the BEST defense against this scenario?


A. Configuring signature-based antivirus to update every 30 minutes
B. Enforcing S/MIME for email and automatically encrypting USB drives upon insertion
C. Implementing application execution in a sandbox for unknown software
D. Fuzzing new files for vulnerabilities if they are not digitally signed