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grpc-protobuf

Detect gRPC and Protocol Buffers service vulnerabilities via reflection and metadata testing.

846|152|Updated Mar 13, 2026
Search Tags:#reconnaissance#protobuf#grpc#auth-bypass#grpcurl#message-tampering#injection-testing
One-click install
npx skills add https://github.com/xalgord/xalgorix --skill grpc-protobuf-xalgord
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: grpc-protobuf
Source: https://github.com/xalgord/xalgorix/tree/main/internal/tools/skills/data/protocols/grpc-protobuf
Command: npx skills add https://github.com/xalgord/xalgorix --skill grpc-protobuf-xalgord

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This skill provides concise operational guidance to find and verify security weaknesses in gRPC and Protocol Buffers implementations, reducing the time required to discover reflection exposure, metadata-based authentication bypasses, message tampering, and injection vectors.

Core Features & Use Cases

  • Service Discovery & Reconnaissance: Techniques to detect gRPC endpoints, check reflection, and enumerate services and methods.
  • Authentication & Metadata Testing: Methods to probe for authorization bypasses using forged or missing metadata headers.
  • Message Tampering & Injection: Strategies to test for IDORs, parameter manipulation, SQL injection, and command injection in protobuf string fields.
  • Use Case: Assess an internal microservice running on TARGET:50051 to enumerate services, test method-level authorization, and verify input handling for injection flaws.

Quick Start

Scan the target gRPC service at TARGET:50051 for reflection, list services and methods, and attempt metadata-based authentication bypasses and simple message tampering tests.

Frequently Asked Questions about grpc-protobuf

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I test gRPC services for reflection exposure and method enumeration?▼

To test gRPC services for reflection exposure, you scan target endpoints like TARGET:50051 to detect enabled reflection and enumerate available services and methods. This reconnaissance identifies exposed gRPC interfaces for further security assessment.

What is a metadata-based authentication bypass in gRPC and how do I check for it?▼

A gRPC metadata-based authentication bypass occurs when forged or missing metadata headers grant unauthorized access. You check for this vulnerability by probing target endpoints with manipulated authentication metadata to verify method-level authorization controls.

Can I test Protocol Buffers message fields for SQL injection and parameter manipulation?▼

Yes, you can test Protocol Buffers message fields for SQL injection and parameter manipulation by performing message tampering. This involves fuzzing protobuf string fields with injection payloads to verify if the gRPC service properly sanitizes input handling.

Does this gRPC security testing approach work with gRPC-Web and plaintext HTTP/2 endpoints?▼

Yes, this gRPC security testing approach applies to plaintext and HTTP/2 gRPC endpoints as well as gRPC-Web interfaces. It supports service discovery, method enumeration, and metadata handling tests across these communication protocols.

Do I need grpcurl to perform gRPC vulnerability scanning and fuzzing requests?▼

Yes, you need access to grpcurl or an equivalent tool to perform gRPC vulnerability scanning. The testing process requires the ability to send HTTP/2 or plaintext gRPC requests to target ports for fuzzing and reconnaissance.

Why should I scan internal microservices for gRPC input handling and IDOR vulnerabilities?▼

You should scan internal microservices for gRPC input handling and IDOR vulnerabilities to identify parameter manipulation and injection vectors. Testing verifies that message tampering cannot exploit insecure direct object references in protobuf fields.

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