Grityu/model_duplication ("five modes duplication", 2023) built and evaluated ML traffic classifiers (Knn_test.py, ScenarioA.pkl, features.json) using CICFlowMeter flow-feature extraction over labeled pcap captures of major commercial VPN/circumvention tools — Psiphon (including a specific "psiphon_operation" capture), Surfshark over OpenVPN TCP/UDP, TorGuard over OpenVPN UDP and "OpenVPN over SSL", and Hotspot Shield VPN — directly evidencing GFW-side R&D on flow-level statistical fingerprinting of specific VPN products.
REPO PATH: Grityu/model_duplication.bundle; deleted-file commit history references sufshark_openvpn_tcp.pcap, surkshark_openvpn_udp.pcap, torguard_openvpn_udp.pcap, TorGuard_openvpnOverSSL.pcap, HotSpotshieldVPN_纯净流量.pcap, psiphonz纯净流量.pcap, 20230309_fxy_psiphon_operation.pcapng, test_cicflowmeter.py, Knn_test.py, ScenarioA.pkl, features.json
Defense implications
- Lantern's OpenVPN-based or OpenVPN-mimicking transports should assume MESA Lab has trained flow-level (CICFlowMeter-style) ML classifiers directly against Psiphon, Surfshark, TorGuard and Hotspot Shield OpenVPN traffic; distinctive flow statistics (packet-size/timing distributions) from these specific products should not be treated as safe cover traffic to imitate.
Related findings
The same internal research note's second research point develops an ML-based detector for Geneva-style automated censorship-evasion traffic; simple flow-level features (flow size, max packet size, RST/SYN/FIN flag counts, forward init-window bytes, inter-arrival timing) achieve near-perfect (ROC-AUC ~1.00) classification of Geneva-generated evasion traffic against CICIDS2017 and MAWI backbone background traffic using decision trees, LightGBM, XGBoost and random forest, with abnormal flow size (~150 bytes vs. 1000-30000 bytes typical) identified as the single most discriminative feature.
A 2020 IIE CAS master's thesis (author and advisor names redacted) develops ML methods to identify audio/video traffic within encrypted flows without payload inspection, by quantifying on/off transmission burst patterns and binning long packet-length/timing sequences into short fixed-length feature vectors usable from as little as 5 seconds of traffic, plus a lightweight heuristic-threshold variant with a congestion-correction feature scheme built into a deployed identification system.
A 2020 MESA Lab monthly report describes building a sapp plugin that extracts packet-sequence features specifically "for DoH (DNS-over-HTTPS) service discovery," alongside a broader CSTNET DoH measurement-report effort and configuring a DNS-to-DoH gateway -- confirming sapp is used to fingerprint DoH traffic via statistical sequence features rather than plaintext DNS content.
A 2023 IIE/CAS master's thesis (author and advisor names redacted) develops a black-box adversarial-example attack against ML-based malicious-encrypted-traffic classifiers: transferable feature-space perturbations evade LSTM and FS-Net classifiers over 96.2% of the time (over 50.5% against SVM/LR/DNN), and a packet-length-and-timing perturbation algorithm that translates those perturbations into real traffic achieves an 82.1% evasion rate, 29.9 points higher than the prior state-of-the-art black-box method.
A 2024 IIE/CAS PhD opening-report (author and advisor names redacted) lays out a four-part research plan for identifying specific encrypted video content transmitted over QUIC: (1) recovering per-video traffic fingerprints from downlink packet aggregation despite QUIC's full encryption, using linear-fit correction to reconstruct true video-chunk sizes; (2) matching randomized multi-segment video combinations via a random-walk segment model plus a traffic 'language model'; (3) a Siamese attention-CNN with contrastive learning to fingerprint-match mixed audio/video segment streams; and (4) a large-model-based classifier to keep fingerprint matching robust under network degradation and varied playback modes.
A 2020 IIE/CAS master's thesis (author and advisor names redacted; the advisor is a recurring MESA Lab supervisor named throughout this corpus), 'Research on Key Technologies of SSL Client Identification for Network Traffic,' proposes labeling training data by decrypting sessions through an SSL transparent-proxy MITM to auto-tag which client application generated each session, then builds a real-time classifier fusing SSL handshake (ClientHello) fingerprints with SSL 'Burst' packet-timing/size features to identify the client application without further decryption, validated against WhatsApp, WeChat, and Facebook traffic.