CompTIA Security+ Question J-60

A security researcher wants to reverse engineer an executable file to determine if it is malicious. The file was found on an underused server and appears to contain a zero-day exploit. Which of the following can the researcher do to determine if the file is malicious in nature?

A. TCP/IP socket design review
B. Executable code review
C. OS Baseline comparison
D. Software architecture review

Answer: C

Zero-Day Exploits begin exploiting holes in any software the very day it is discovered. It is very difficult to respond to a zero-day exploit. Often, the only thing that you as a security administrator can do is to turn off the service. Although this can be a costly undertaking in terms of productivity, it is the only way to keep the network safe. In this case you want to check if the executable file is malicious. Since a baseline represents a secure state is would be possible to check the nature of the executable file in an isolated environment against the OS baseline.