hunt-http-smuggling

Imported from sickn33/agentic-awesome-skills (skills/hunt-http-smuggling/SKILL.md). Install upstream with npx skills add sickn33/agentic-awesome-skills --skill hunt-http-smuggling. Copyright stays with the author (MIT).

⚠️ 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)

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.

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

# Read-only first step; confirm scope before anything active.
cat scope.txt  # target list from the authorized engagement brief

Adapted from 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.