IIA Exam IIA-CIA-Part3 Topic 12 Question 75 Discussion

A manager at a publishing company received an email that appeared to be from one of her vendors with an attachment that contained malware embedded in an Excel spreadsheet . When the spreadsheet was opened, the cybercriminal was able to attack the company's network and gain access to an unpublished and highly anticipated book. Which of the following controls would be most effective to prevent such an attack?