At least once a week someone comes to me with an unexplainable, random problem that they begin to think might be malware-related. Security people usually have a strong understanding of host and network mechanics and years of experience. When faced with the “unexplainable problem,” the best thing you can do is to figure out what the problem isn’t. Troubleshoot along the OSI model, don’t forget to check physical connections, check Wireshark and sniff a workstation.”]
Source: https://www.csoonline.com/article/2633137/to-solve-the-unsolvable-problem.html