llm-indirect-prompt-injection

llm-indirect-prompt-injection is a skill for Claude Code, Codex from ShulkwiSEC/bb-huge. It costs 91 tokens per session (2,896 once invoked), scanned A, original, MIT.

A security-testing guide for finding indirect prompt injection flaws, where hostile instructions are hidden in websites, emails, documents, database records, or other external content an AI reads. It focuses on systems that retrieve, summarize, or analyze outside data.

In plain words
What is it for?
Use it for authorized testing of AI search, summarization, browsing, content moderation, and multi-agent systems that process external data.
Why use it?
It helps reveal whether untrusted content can change an AI assistant's behavior or influence connected tools.

Skill for Claude CodeCodex

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

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is - [`_shared/references/elite-chaining-strategy.md`](../_shared/references/elite-chaining-strategy.md) — Exploit chaining methodology and high-payout chain patte.

Good fit Use it for authorized testing of AI search, summarization, browsing, content moderation, and multi-agent systems that process external data.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/ShulkwiSEC/bb-huge
agentmods
npx agentmods add skills/shulkwisec/bb-huge/llm-indirect-prompt-injection

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 llm-indirect-prompt-injection

README.md
[![agentmods](https://agentmods.dev/badge/skills/shulkwisec/bb-huge/llm-indirect-prompt-injection/github.svg)](https://agentmods.dev/skills/shulkwisec/bb-huge/llm-indirect-prompt-injection)
Your own site
<a href="https://agentmods.dev/skills/shulkwisec/bb-huge/llm-indirect-prompt-injection"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/llm-indirect-prompt-injection/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 llm-indirect-prompt-injection

Your own site · 80×15
<a href="https://agentmods.dev/skills/shulkwisec/bb-huge/llm-indirect-prompt-injection"><img src="https://agentmods.dev/badge/skills/shulkwisec/bb-huge/llm-indirect-prompt-injection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,896 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. ✓ AI security review Sonnet 5 · 7 Sept 2026 📄 Read the review
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 $0.00091 $0.02896
Opus 5 $0.00046 $0.01448
Sonnet 5 $0.00018 $0.00579
Haiku 4.5 $0.00009 $0.00290

Measured 7d ago against content hash 0a4016d711e2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

llm-indirect-prompt-injection scanned grade A with 0 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 7d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/process.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

skills/curated/llm-indirect-prompt-injection/SKILL.md · 343 lines

How it starts

The opening of the file, as written. The whole thing — 343 lines — stays where its author put it; the contents beside it link to each section on GitHub.

LLM Indirect Prompt Injection

When to Use

  • When LLM-integrated apps process external content (web pages, emails, documents)
  • When AI assistants summarize or analyze user-generated content
  • When AI tools ingest third-party data sources
  • When testing AI-powered search, summarization, or analysis features
  • When assessing multi-agent systems where agents process each other's outputs

Prerequisites

  • Access to target AI/ML system or local model deployment for testing
  • Python 3.9+ with relevant ML libraries (transformers, torch, openai)
  • Understanding of LLM architecture and prompt processing pipelines
  • Authorized scope and rules of engagement for AI red team testing

Workflow

Phase 1: Identify Injection Surfaces

# Indirect injection surfaces — where external data enters the LLM context:

INJECTION_SURFACES = {
    "web_content": {
        "description": "LLM browses/summarizes web pages",
        "injection_point": "Place malicious instructions in web page text",
        "examples": [
            "AI search agent summarizes web results",
            "Chatbot reads URLs shared by users",
            "Content moderation AI reviews web pages",
        ]
    },
    "email_processing": {
        "description": "LLM reads/processes emails",
        "injection_point": "Embed instructions in email body/subject",
        "examples": [
            "AI email assistant that summarizes inbox",
            "AI that drafts replies to emails",
            "AI that categorizes support tickets from email",
        ]
    },
    "user_generated_content": {
        "description": "LLM processes user profiles, reviews, comments",
        "injection_point": "Place malicious text in user-controlled fields",
        "examples": [
            "AI that summarizes product reviews",
            "AI that reads user profiles/bios",
            "AI that processes forum posts",
        ]
    },
    "document_processing": {
        "description": "LLM reads uploaded documents (PDF, DOCX, etc.)",
        "injection_point": "Embed instructions in document text",
        "examples": [
            "AI document analyzer/summarizer",
            "AI-powered resume screener",
            "AI contract review tool",
        ]
    },
    "database_records": {
        "description": "LLM queries and processes database content",
        "injection_point": "Store malicious text in database fields",
        "examples": [
            "AI customer support reading ticket history",
            "AI analytics querying user data",
            "AI assistant accessing CRM records",
        ]
    },
    "api_responses": {
        "description": "LLM processes responses from external APIs",
        "injection_point": "Compromise API to inject malicious responses",
        "examples": [
            "AI agent calling external APIs for information",
            "AI that processes webhook payloads",
            "AI financial assistant reading market data APIs",
        ]
    }
}

Read the full file on GitHub · 343 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 7d ago First seen · 343 lines · 91 tokens per session scan E 0a4016d711e2

Subscribe to this mod's changes

llm-indirect-prompt-injection is a skill published in the GitHub repository ShulkwiSEC/bb-huge (22 stars, last pushed 2mo ago), licensed MIT. It adds 91 tokens to every session and 2,896 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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