A multistage infection chain is an attack that delivers malicious components in a sequence instead of dropping one obvious payload. One stage may be a phishing email, the next a script, archive, or web page, and the final stage may fetch or unpack the real malware.
This matters because each step can look harmless on its own, which helps attackers evade static detection and slows analysis. Defenders often need to reconstruct the full path from email, document, and script activity to see the true objective. In real campaigns, staged delivery is used to hide loaders, delay payload exposure, and make network or endpoint alerts harder to correlate. Detection usually focuses on unusual parent-child process chains, suspicious downloads, macro or script execution, and repeated handoffs between files and processes.