Laravel Intercept package blocks malicious prompts and data leaks

Prerequisites & Compatible Environments

Before implementing this security layer, ensure your stack matches these requirements:

• PHP 8.4 or higher
• Laravel framework setup
• Laravel AI SDK (currently stable on version 0.8)

Essential Middleware Libraries & Packages

To implement this setup, we rely on:

• promptphp/intercept: The core library providing security guards for your LLM inputs.
• Laravel AI SDK: The integration package for AI services like OpenAI.

Implement Security Guards in Your Code

Integrating security middleware is straightforward. You declare the middleware inside your agent class using the middleware method:

namespace App\Agents;

use PromptPHP\Intercept\Middleware\InjectionGuard;
use PromptPHP\Intercept\Middleware\PersonalInformationRedactor;

class SupportAgent extends Agent
{
    public function instructions(): string
    {
        return 'You are a helpful customer support agent.';
    }

    public function middleware(): array
    {
        return [
            new InjectionGuard(action: 'block'),
            new PersonalInformationRedactor(action: 'redact'),
        ];
    }
}

In this setup, InjectionGuard scans for prompt injection patterns. If it finds a threat, it halts the request. Meanwhile, PersonalInformationRedactor scrubs sensitive patterns like credit card numbers or emails.

Intercept Actions: Redact, Mask, or Block

The package offers fine-grained control over how threats are handled:

• Redact: Replaces sensitive data with generic placeholders (e.g., hiding emails) before sending payloads to OpenAI.
• Block: Completely stops execution and returns a safe, pre-configured error message directly to the user.

The Limits of RegEx-Based Security Guards

Do not treat this package as an impenetrable firewall. Under the hood, these guards rely on regular expressions to identify common attack patterns. Sophisticated attackers constantly find ways to bypass pattern-matching rules. Use this package as a fast, first line of defense, but keep your ultimate backend security layered.