Adding nine beacon descriptors (inter-arrival-time moments, FFT peak period and power, flow count per endpoint triple, idle ratio) to the flow-statistics view improves Random Forest F1 from 0.747 to 0.856 (+0.109) — one order of magnitude larger than any multi-view fusion gain (+0.022). However, the top-weighted feature beacon_n_flows correlates with capture length (Spearman ρ = 0.718) and its single-feature ROC-AUC varies from 0.173 to 0.977 across folds, indicating it partly reflects a collection artifact rather than real beacon periodicity.
From 2026-nguyen-huu-multi-view-fusion-encrypted — Multi-View Fusion for Encrypted C2 Detection: A Leakage-Controlled Measurement Study of Evaluation Pitfalls
· §V-C
· 2026
· arXiv preprint
Implications
Periodic callback timing regularity (beacon interval, FFT periodicity) is the single highest-value ML detection signal for encrypted C2 — circumvention transports using any form of periodic heartbeat or polling must randomize callback timing with substantial jitter to defeat this feature class.
Limiting the number of flows per server address or multiplexing within a single long-lived connection reduces the flow-count-per-destination signal that functions as a strong detection artifact in grouped traffic analysis.