--- name: hunt-http-smuggling description: Hunt HTTP request smuggling (CL.TE, TE.CL, H2.CL, H2.TE). category: security risk: offensive source: https://github.com/elementalsouls/Claude-BugHunter source_repo: elementalsouls/Claude-BugHunter source_type: community date_added: '2026-09-20' license: MIT license_source: https://github.com/elementalsouls/Claude-BugHunter/blob/main/LICENSE compatibility: Requires explicit written authorization for a target scope plus the relevant testing tools for this technique. Docs-only; helper scripts and commands not bundled. sources: hackerone_public, cve_database, portswigger_research, public_research report_count: 12 --- > **⚠️ AUTHORIZED USE ONLY** > This skill is for educational purposes or authorized security assessments only. > You must have explicit, written permission from the system owner before using this tool. > Misuse of this tool is illegal and strictly prohibited. > **Mandatory confirmation gate** > Before running any command that probes, exploits, changes, persists on, extracts data from, or attempts credential access against a target: > 1. Ask the user to state the exact target URL, IP, account, or resource. > 2. Ask the user to confirm written authorization and the permitted scope. > 3. Show the exact command(s) and explain their expected effect. > 4. Wait for explicit confirmation in the current conversation. > > Without that confirmation, remain read-only and provide defensive guidance only. Prefer a sandbox, disposable VM, or controlled lab. ## HTTP REQUEST SMUGGLING > Parser disagreement between hops requires controlled validation; bounty amounts and duplicate rates are not established here. ### CL.TE (Content-Length front, Transfer-Encoding back) ```http POST / HTTP/1.1 Content-Length: 13 Transfer-Encoding: chunked 0 SMUGGLED ``` ### Detection ``` 1. Burp extension: HTTP Request Smuggler 2. Right-click request → Extensions → HTTP Request Smuggler → Smuggle probe 3. Manual timing: CL.TE probe + ~10s delay = backend waiting for rest of body ``` ### Impact Chain ``` Poison next request → access admin as victim Steal credentials → capture victim's session Cache poisoning → stored XSS at scale ``` --- ## Topology and controlled validation Do not infer safety or vulnerability from a Server header or broad product/version matrix. Identify the actual client/front-end/origin protocol, exact release, configuration, connection reuse and vendor advisory. Header banners may be hidden or forged. HTTP/2 downgrading can introduce inconsistencies, but HTTP/2 alone does not prove a flaw. Use a tool that supports the specific wire protocol and disable automatic content-length rewriting only in an isolated authorized lab. Timing changes can result from network jitter or rejection; compare repeated baseline/control probes within the permitted request budget, then demonstrate cross-request interference with two accounts and connections you control. Never harvest real users' headers or poison a shared production cache. Use a harmless unique marker, isolated cache key, stop condition and cleanup plan. If third-party traffic could be affected, stop and reproduce in the owner's isolated environment. The inline HTTP fragment is a byte-sensitive teaching sketch, not a ready probe: include Host, explicit CRLF and correct encoded lengths for the chosen transport. Reference: [PortSwigger request smuggling](https://portswigger.net/web-security/request-smuggling). ## Related Skills & Chains - **`hunt-cache-poison`** — Smuggling + cache is the canonical critical chain; one smuggled request becomes the cached response for every subsequent victim. Chain primitive: CL.TE smuggle a request whose response body contains attacker HTML/JS → front-end cache stores it under a popular URL (`/`, `/login`) → de-sync poisoning where the smuggled request becomes the cached response for the next N victims, persisting for the cache TTL. - **`hunt-auth-bypass`** — Smuggling reaches internal-only routes that the front-end WAF/auth-proxy filters out. Chain primitive: smuggle `GET /admin/users HTTP/1.1` past the front-end ACL that blocks external `/admin/*` → backend processes the smuggled request as if from a trusted internal source → bypass front-end auth by smuggling internal-routed request → admin data in the response queue. - **`hunt-idor`** — Smuggling attaches the NEXT user's session cookies to an attacker-controlled request path. Chain primitive: smuggle `GET /api/me HTTP/1.1` with no cookies → backend pairs it with the next legitimate user's incoming connection cookies → victim's session cookie attached to attacker's smuggled request → attacker reads the response containing victim's PII/tokens. - **`hunt-xss`** — Smuggling injects XSS payloads into the response stream of the next victim without ever appearing in a URL parameter. Chain primitive: smuggled request body contains reflected payload that the backend renders into the next response in the queue → next visitor to `/` receives attacker HTML inline → reflected XSS at every visitor without any URL parameter visible to them or to logs. - **`security-arsenal`** — Reach for the smuggling payload bank (CL.TE / TE.CL / TE.TE obfuscations, H2.CL downgrade probes, h2csmuggler one-liners, Burp HTTP Request Smuggler extension config) and the time-delay confirmation template before manual hex-editing. - **`triage-validation`** — Run the Pre-Severity Gate before claiming Critical: the smuggled-request effect MUST land on a request issued by a different client/session, not merely a timing anomaly; use a separate controlled test client, never an unsuspecting user. A timing delta in your own browser alone is parser disagreement, not exploitable smuggling. ## When to Use - You have explicit, written authorization to assess the target in scope, and the task matches this skill's vulnerability class or technique within a bug-bounty or penetration-test engagement. - You need the recon, exploitation, or validation workflow described below — executed strictly inside the approved scope. ## Limitations - Authorized scope only: the confirmation gate above is mandatory before any probing, exploitation, or credential-access command. - Docs-only import: upstream helper scripts, commands, engine, and research assets are not bundled; reinstall tooling from the source repo when needed. - Validate every finding (see `triage-validation`) before reporting; report via `report-writing`. Prefer a sandbox, disposable VM, or controlled lab. ### Example ```bash # Read-only first step; confirm scope before anything active. cat scope.txt # target list from the authorized engagement brief ``` > Adapted from [elementalsouls/Claude-BugHunter](https://github.com/elementalsouls/Claude-BugHunter) (MIT); frontmatter, When to Use/Limitations, and safety boundaries added for upstream compliance. Docs-only import: executable helpers, commands, engine, and research assets not bundled.