Linkage analysis is a defensive investigation method that connects related accounts, devices, IP addresses, browser fingerprints, domains, and other infrastructure to expose coordination that is not obvious from any single record. Instead of judging one account in isolation, analysts look for shared traits and repeated relationships that suggest a common operator, fraud ring, or bot-driven campaign.
This matters because many attacks are designed to stay below per-account thresholds. One login may look normal, but a cluster of accounts that reuse the same device, payment instrument, or hosting infrastructure can reveal organized abuse. In practice, linkage analysis supports fraud detection, abuse investigation, and incident response by turning scattered indicators into a network view. Defenders use it to prioritize review, trigger step-up verification, or block connected assets when individual alerts are too weak to act on alone.