VirusTotal aggregates multiple antivirus products and online scan engines to check for viruses and malware, and it provides results about files and URLs to the user. It is the best option for checking if a file has been previously identified as malicious by various antivirus engines. Hashing a file may allow an analyst to check a specific hash against known databases, but it does not provide the comprehensive analysis of multiple engines. Checking firewall logs would not help to identify a file as malicious; it may only show that the file has been transferred. Reviewing application logs can reveal irregularities or evidence of malware execution but does not directly correlate with antivirus engine determinations.