Chunked transfer coding is an HTTP mechanism that sends a message body in smaller pieces, or chunks, instead of requiring the sender to know the total size up front. The receiver rebuilds the full response or request after all chunks arrive. This is normal web behavior and is part of standard HTTP handling.
In cyber security, it matters because attackers can hide malicious traffic inside ordinary-looking HTTP transfers. Malware may use chunked uploads for command-and-control communication, staged payload delivery, or data exfiltration. Defenders should not treat chunked encoding itself as malicious; the warning sign is the context, such as unusual URI paths, repeated PUT uploads, stable request patterns, or a process that rarely speaks HTTP suddenly sending chunked traffic. Monitoring these patterns helps identify threats even when domains change.