An internal experiment using BurpSuite as a MITM proxy tests injecting a forged QUIC ServerHello carrying a connection-close frame ahead of the real server response, to make the client abandon its QUIC handshake; the author separately proposes recording every site known to support QUIC and simply blocking plain TCP connections to those sites, on the theory that this indirectly forces QUIC off since a censor cannot otherwise tell in advance which TCP flow would have upgraded to QUIC.
测试通过第三方注入带有连接关闭帧的serverHello,及时关闭客户端发出的quic初始数据包clientHello...如果把所有支持quic的网站都记录下来,屏蔽这些网站的tcp连接(关闭tcp连接),不就也可以关闭通往这些网站的quic连接了吗?
Defense implications
- A QUIC-capable-site allowlist used to selectively block plain TCP (forcing traffic onto interceptable transports) is a plausible GFW tactic under active exploration; protocols/services that don't leak an early plaintext 'I support QUIC' signal, or that make TCP and QUIC equally hard to attribute to the same service, reduce exposure to this specific technique.
Related findings
An internal TSG functional-requirements spec ('加密协议JG') defines device support for identifying and blocking ECH, ESNI and QUIC traffic via per-connection SNI/region-matching tables (e.g. DF_QUIC_REGION), plus a companion 'FD报文全流程感知' feature that both passively monitors and actively injects synthetic verification traffic end-to-end through the network path to compute a live per-rule 'CT率' (breakthrough/penetration rate) — the system self-measures how often its own QUIC/ESNI/ECH blocks fail to take effect, and separately throttles logging/blocking detail for rule IDs receiving unusually high hit counts (DF_ATTACK_PROTECTION, 'targeted attack detection').
A MESA Lab thesis/report states that ESNI/ECH protocol-identification technology, based on TLS extension field type numbers, "has already been applied in actual projects," and lists the researcher's own project participation as "G1系统 - ESNI、ECH加密协议识别" (Feb-Aug 2023) and "G1系统 - QUIC协议旁路ZD" (Feb-Nov 2023, QUIC bypass/blocking), plus a separately implemented "DNS主动探测模块" (DNS active-probing module, marked 已实现/already implemented). "G1" also appears independently as a named legacy system in the Maat/Transformer DPI header (PROTO_VPN comment: "G1历史遗留"), corroborating it as a real internal system name, not a typo.
A MESA Lab repo (shihaoyue/yy_deploy_script) contains an organized suite of active attack tooling specifically targeting encrypted DNS: DoH/DoT downgrade attacks, DoH/DoT DDoS including a CVE-2024-4487 (HTTP/2 Rapid Reset) exploit script, IPv6 DNS response spoofing/injection (fakedns6 using forged-source-address "saddns"), a DNSSEC-downgrade proxy, DNSSEC-DDoS tooling, and an active DNS-fingerprinting probe pair (fpdns_client/fpdns_server under a folder named "TargetGZ"). This is direct evidence of GFW-adjacent R&D that specifically attacks the encrypted-DNS protocols (DoH/DoT) circumvention tools often rely on for resolver privacy.
An internal TSG operations/troubleshooting manual lays out TSG's full traffic pipeline (NIC -> mrzcpd/marsio capture driver -> sapp DPI engine -> firewall/proxy(KNI->TFE)/active-defense/WAN-NAT policy branches) and shows engineers using maat_redis_tool to pull the live Redis-synced blocking policy tables (TSG_SECURITY_COMPILE, TSG_OBJ_IP_ADDR, TSG_OBJ_APP_ID) and filter them by numeric policy/object ID to debug why a block rule isn't firing.
A 2023 MESA Lab monthly report describes the 'TF' project's active-defense work: test cases for serial ('串联') HTTP hijack/tamper and parallel ('并联') DNS race-injection ('DNS抢答'), performance tuning that scaled active-defense capacity from 3 to 5 units, converting two existing TSG boxes to active-defense mode, and rewriting the active-defense flow-control logic to no longer depend on sapp.
A MESA Lab monthly report states that adjustments to a VPN-detection module accumulated over 10,000 Psiphon3 server IPs and delayed a Psiphon3 client's ability to get online by at least 3 minutes in the researchers' test environment, an earlier-stage data point consistent with the much larger-scale (~70-73K IP) 'vpn-thwarting'/CyberNarrator Psiphon-harvesting pipeline documented elsewhere in this corpus.