grpc-web-pentest SKILL.md skillA
grpc-web-pentest from dreadnode/capabilities is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add dreadnode/capabilities/grpc-web-pentest@git:20260518.7b5f854Pins git:20260518.7b5f854 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- dreadnode/capabilities
- Path
capabilities/web-security/skills/grpc-web-pentest/SKILL.md- Versions recorded
- 1
- Latest version
- git:20260518.7b5f854, committed May 18, 2026
- Size
- 3,743 bytes
- Repository stars
- 22
- License
- MIT
Pentest gRPC-Web services via CORS abuse, JSON transcoder bypass, and payload manipulation. Use when target serves application/grpc-web content type, has Envoy/APISIX proxy, or JS bundles contain protobuf service definitions.
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# gRPC-Web Pentesting gRPC-Web wraps protobuf in HTTP/1.1 for browser clients. The translation layer (Envoy, APISIX, grpcwebproxy) introduces attack surface absent in native gRPC. ## Detection - Content-Type: `application/grpc-web` or `application/grpc-web-text` - `x-grpc-web: 1` header in requests - JS bundles importing `grpc-web` or containing `.proto` service paths - Envoy proxy headers (`x-envoy-upstream-service-time`) ## Recon: Extract Services from JS JS bundles embed service paths and message schemas: ```bash # grep for service method paths (pkg.Service/Method format) grep -oP '[a-zA-Z0-9_.]+/[A-Z][a-zA-Z]+' main.*.js | sort -u # Find proto message field definitions grep -oP 'proto\.[a-zA-Z]+\.[a-zA-Z]+' main.*.js | sort -u ``` Also check for `buf` reflection: ```bash buf curl --protocol grpcweb https://target.tld --list-methods ``` ## CORS on gRPC-Web gRPC-Web requires CORS for browser calls. Test the proxy's CORS config: ```bash curl -I -X OPTIONS https://target.tld/pkg.Service/Method \ -H 'Origin: https://evil.tld' \ -H 'Access-Control-Request-Method: POST' \ -H 'Access-Control-Request-Headers: content-type,x-grpc-web,authorization' ``` …
Read the whole file at its exact version.
How to install
mdr add dreadnode/capabilities/grpc-web-pentest@sha256:ce50cb61d0c557aaThe line at the top of this page pins the label git:20260518.7b5f854, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_etssm7qpyy3ezjbb)
3 badge image fetches in 30 days. What the badge shows.
Versions
The registry has recorded 1 version of this file, committed on May 18, 2026.
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (3743 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
dreadnode/capabilities · 22 stars · license MIT · pushed 2026-11-02 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_etssm7qpyy3ezjbb GET https://markdownregistry.com/api/v1/resolve?ref=dreadnode/capabilities/grpc-web-pentest GET https://markdownregistry.com/api/v1/blob/ce50cb61d0c557aa7e663bca8b32b9d222ad6138665e2bb38b790b49aee19ced
Your AI assistant does the legwork. You hear about the deals worth your word. Hand yours the standing instructions at modelranch.com and it joins the network that reads files like this one.
Guides: the SKILL.md format and its required fields · what to check before you install a skill · how to pin a skill to an exact version · where to find agent skills · keeping a team on the same skills · which agent file does what.