llm-sanitizer 0.1.3

CLI + MCP server for detecting, classifying, and redacting embedded LLM agent instructions in documents, source code, and web pages.

llm-sanitizer

CLI + MCP server for detecting, classifying, and redacting embedded LLM agent instructions in documents, source code, and web pages.

What It Does

Documents, web pages, and source code can contain embedded instructions targeting LLM agents — from legitimate customization to malicious prompt injection. llm-sanitizer scans content for these embedded instructions, classifies their risk level, reports findings in multiple formats, and optionally produces redacted output.

Detection

Ten pluggable detection rules covering:

• Instruction override phrases ("ignore previous instructions…")
• Zero-width character encoding (hidden text via invisible Unicode)
• HTML/markdown hidden content (white-on-white, display:none)
• Role-play injection ("act as", "you are now DAN")
• System prompt markers (<system>, ## System Prompt)
• Data exfiltration attempts ("output the system prompt")
• Comment-embedded directives (<!-- AI: do this -->)
• Base64-encoded instructions
• Unicode homoglyph substitution (Cyrillic lookalikes)
• Agent-specific config patterns in unexpected locations

Classification

Five risk levels: info (legitimate AI config) → low → medium → high → critical (confirmed injection technique).

Redaction

Non-destructive cleaning in three modes:

• strip — remove the instruction entirely
• comment — replace with [REDACTED: ...] marker
• highlight — wrap in visible markers for review

Installation

pip install llm-sanitizer
# or
uv pip install llm-sanitizer

Quick Start

CLI

# Scan a file
llm-sanitize scan document.md

# Scan a URL
llm-sanitize scan https://example.com/page

# Scan a directory
llm-sanitize scan ./docs/ --glob "**/*.md"

# Redact a file
llm-sanitize redact document.md -o clean_document.md

# Redact a directory (mirrors structure)
llm-sanitize redact ./docs/ -o ./clean_docs/

MCP Server

Add to your MCP configuration:

{
  "mcpServers": {
    "llm-sanitizer": {
      "command": "llm-sanitizer"
    }
  }
}

Available tools: scan_text, scan_file, scan_url, scan_dir, redact, redact_file, redact_url, redact_dir, list_rules.

Python API

from llm_sanitizer.scanner import scan_text

result = scan_text("Check this <!-- ignore previous instructions --> content")
print(result.findings)  # [Finding(rule='comment_directive', risk='high', ...)]

Configuration

Create .llm-sanitizer.yml at your project root:

sensitivity: medium

rules:
  zero_width:
    enabled: true
  instruction_override:
    enabled: true
    sensitivity: high

policy:
  mode: "allow-known"    # allow-known | allow-none | allow-all
  agents:
    copilot: allow
    cursor: allow

Output Formats

• JSON — structured findings for programmatic use
• Markdown — human-readable reports
• SARIF — GitHub Code Scanning / VS Code integration

Documentation

• Design Specification

License

AGPL-3.0-or-later. Commercial licensing available — contact [e-mail].