TSG's self-diagnostic suite (tsg/tsg-diagnose) imports the full badssl.com test-certificate corpus (superfish, eDellRoot, mitm-software, captive-portal, revoked, weak-key variants, etc.) to continuously validate its own TLS-interception logic in production, adds test cases for TLS ClientHello fragmentation handling by the intercept engine, and documents that firewall DENY blocking was changed from sending only a FIN to sending FIN-then-RST to close connections.
feature:TSG-22325:Add Proxy Intercept chello fragment cases. ; bugfix:TSG-8020:修复因firewall实现block方式变为先发fin再发送rst包导致自检失败问题
Defense implications
- TSG's MITM/intercept path is explicitly tested against fragmented ClientHellos, so ClientHello fragmentation alone is unlikely to evade TSG's TLS interception.
- TSG's block sequence is FIN then RST (not RST alone) as of this fix — useful as a fingerprint of TSG-originated resets vs. other injectors when triaging a blocking event.
Related findings
The same 224-column TSG per-session log schema carries a full TLS- interception field set — proxy_pinning_status, proxy_intercept_status, proxy_passthrough_reason, proxy_cert_verify, proxy_intercept_error, sc_rsp_raw and sc_rsp_decrypted (raw vs. decrypted server response content) — plus ssl_esni_flag and ssl_ech_flag (explicit ECH/ESNI-usage flags), ssl_ja3_hash/ssl_ja3s_hash, and ssh_hassh (SSH client fingerprinting), confirming certstore-style MITM interception, ECH/ESNI detection, and TLS/SSH fingerprinting are all first-class fields logged on every session, not experimental add-ons.
The tango/kni (Kernel Network Interface) repo shows TSG's SNI/TLS-ClientHello-based interception logic (kni_entry.cpp) receiving dedicated 2024 fixes for handling TLS ClientHello fragmented across multiple packets ("ssl chello frag") and a "chello first packet hit intercept policy" bug, on top of a long-standing (2020) "dynamic bypass" feature that replaced raw-ClientHello matching with JA3 TLS fingerprints, plus counters for SSL certificate-pinning detection.
The tango/tfe ("TFE") engine ships dual root-CA trust stores (tango-ca-trust-ca.pem / tango-ca-untrust-ca.pem, mesalab-ca.pem) for TLS interception plus a JA3-fingerprint-based certificate-pinning detector with a configurable "Dynamic Bypass"; a 2021 bug ticket documents testing this against Firefox without a root cert installed visiting twitter.com, confirming live-target validation of the MITM/pinning-detection pipeline described under the certstore product.
Two independently-leaked TSG session-log CSV exports share an identical 224-field schema whose proxy_* columns (proxy_action, proxy_pinning_status, proxy_intercept_status, proxy_cert_verify, proxy_intercept_error) log the outcome of TLS interception per session, alongside ssl_ja3_hash/ssl_ja3s_hash, ssl_esni_flag, ssl_ech_flag, and quic_sni fields — confirming MITM/cert-pinning-bypass instrumentation and TLS/QUIC fingerprinting are built into TSG's standard traffic-logging pipeline, not a bolt-on feature.
An internal TSG troubleshooting runbook ("HTTPS证书替换策略无效果") documents the certstore MITM-certificate service actively serving/validating forged certificates keyed by SNI, walking an operator through checking certstore logs for specific real-world domains including Google's update service (update.googleapis.com) and Nvidia's GFE service (services.gfe.nvidia.com), and cross-checking keyring config live via maat_redis_tool.
certstore's own commit history documents its transparent-TLS-MITM mechanics directly: it writes the client's observed SNI into the SAN field of the leaf certificate it mints on the fly, supports ECC issuance (secp192r1/secp256r1) for those forged certs, and reads its Trusted/Untrusted decryption-keyring configuration from MAAT's DECRYPTION_KEYRING table -- confirming the interception pipeline end-to-end: client SNI in, matching forged certificate out, gated by MAAT-synced keyring policy.