smuggling

smuggling is a skill for Claude Code, Codex from PurpleAILAB/Decepticon. It costs 97 tokens per session (9,628 once invoked), scanned B, original, Apache-2.0.

A guide to HTTP request smuggling, where a proxy and the backend disagree about where one HTTP request ends and the next begins.

In plain words
What is it for?
It is for testing parser disagreements, request desynchronization, proxy bypasses, and attacks involving HTTP/1.1, HTTP/2, or pipelined requests.
Why use it?
It helps find authorization and routing flaws at the boundary between front-end servers and backend applications.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It is for testing parser disagreements, request desynchronization, proxy bypasses, and attacks involving HTTP/1.1, HTTP/2, or pipelined requests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/purpleailab/decepticon/smuggling
About the project

Decepticon is an autonomous red-team agent that coordinates AI agents, security tools, sandboxes, and supporting services for authorized cybersecurity assessments. Security researchers and red teams can run it through its Docker stack, cloud service, command-line interface, or Python SDK, with the catalogue entries representing its available skills.

PurpleAILAB/Decepticon · 5,497 stars · on GitHub · decepticon.red

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add PurpleAILAB/Decepticon --skill smuggling
Clone the repo
git clone --depth 1 https://github.com/PurpleAILAB/Decepticon

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for smuggling

README.md
[![agentmods](https://agentmods.dev/badge/skills/purpleailab/decepticon/smuggling/github.svg)](https://agentmods.dev/skills/purpleailab/decepticon/smuggling)
Your own site
<a href="https://agentmods.dev/skills/purpleailab/decepticon/smuggling"><img src="https://agentmods.dev/badge/skills/purpleailab/decepticon/smuggling/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for smuggling

Your own site · 80×15
<a href="https://agentmods.dev/skills/purpleailab/decepticon/smuggling"><img src="https://agentmods.dev/badge/skills/purpleailab/decepticon/smuggling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 97 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 9,628 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 2 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 292
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
  • medium Data Exfiltration · line 545
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00097 $0.09628
Opus 5 $0.00048 $0.04814
Sonnet 5 $0.00019 $0.01926
Haiku 4.5 $0.00010 $0.00963

Measured 9d ago against content hash 2facc660c119, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade B, and why

smuggling scanned grade B with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl -s -i -c cookies.txt -d "username=$LOW_USER&password=$LOW_PASS" "$TARGET/<login_path>" | tee login.txt

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

| 1 | `curl -sv <TARGET>/` 2>&1 \| grep -iE '^(server\|via\|x-)' | First-line tier (front-most CDN/WAF/MITM banner) |
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • smuggling — 95% identical, 3 lines differ
packages/decepticon/decepticon/skills/standard/exploit/web/smuggling/SKILL.md · 657 lines

How it starts

The opening of the file, as written. The whole thing — 657 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HTTP Request Smuggling (Desync)

Exploits parser disagreement between two HTTP intermediaries on the same connection (front-end CDN/proxy ↔ back-end origin). When one side ends a request at byte X and the other at byte Y, the bytes between X and Y are the "smuggled" prefix of the next victim request — letting the attacker rewrite the next user's request, steal cookies/headers, or hit auth-bypassed routes.

When This Skill Is Primary

HRS bypasses authentication and authorization at the front-end/back-end boundary — it does NOT need correct credentials. When smuggling_desync (or request_smuggling / hrs / desync) co-occurs with credential-related tags (default_credentials, jwt, weak_password), smuggling IS the primary attack vector. Credential brute-force is a fallback only after the confirm-desync gate (below) fires NEGATIVE.

Reasoning: a CTF that ships both tags is signaling "you have a low-priv account (test:test, etc.) — use it as your session anchor and bypass the role check via parser disagreement." Burning the time budget on admin:* brute-force misses the design entirely. Use the low-priv credentials as the OUTER request session; smuggle the privileged INNER request.

The same logic applies when smuggling_desync co-occurs with cve (the CVE is likely the desync primitive; e.g., CVE-2022-24766 is mitmproxy h1 smuggling — see Variant Catalog → CL.0 / pause-based desync below).

Recognition Signals

Trigger this skill when ANY of the following are present:

  • Multi-proxy stack visible: two Server: strings across responses (e.g. cloudflare then gunicorn); Via: header present; CDN/edge fingerprint (Cloudflare CF-RAY, AWS CloudFront, Akamai, Fastly).
  • Differential 400/501 when sending duplicate/obfuscated Transfer-Encoding or Content-Length headers (one path 200, another 400/501).
  • HTTP/2 frontend with HTTP/1.1 backend (alt-svc: h2, :status pseudo-header, HTTP/2 ALPN). Downgrades are the modern smuggling surface.
  • Pipelining differences: connection reused across requests with inconsistent framing.
  • Challenge tag includes smuggling_desync, request_smuggling, hrs, desync, or recon's "Frontend behavior" line says "frontend forwards malformed framing".
  • Recon handoff notes that the same payload yields different status codes when sent to different proxy hops or with different framing.

Read the full file on GitHub · 657 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 657 lines · 97 tokens per session scan B 2facc660c119

Subscribe to this mod's changes

smuggling is a skill published in the GitHub repository PurpleAILAB/Decepticon (5,497 stars, last pushed 13d ago), licensed Apache-2.0. It adds 97 tokens to every session and 9,628 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it B with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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