Forensic investigation is the disciplined collection, preservation, and analysis of evidence to reconstruct what happened, when it happened, and why. In cyber security, that evidence can include logs, memory captures, network traffic, endpoint artifacts, emails, or cloud audit records. The goal is not only to identify an intrusion or failure, but to preserve proof in a way that can support incident response, legal review, and attribution.
It matters because attackers often try to erase traces, modify timestamps, or hide behind proxies and false flags. A good forensic investigation uses chain-of-custody procedures, timeline analysis, and corroboration across multiple data sources to separate signal from speculation. In real defenses, forensic work helps determine initial access, lateral movement, persistence, data theft, and the scope of impact. In critical infrastructure cases, it can also help decide whether damage was accidental, malicious, or the result of some other operational failure.