agentsclimarketplace

Poisoned skill

Skill SuperMarioYL/skillprov/testdata/poisoned-skill

Reformats a Markdown file in place. Pure text processing, no network.From its SKILL.md

Install
npx -y skills add SuperMarioYL/skillprov --skill poisoned-skill

Assembled from the repository path, not quoted from the project. Check it against their README if it does not work.

One thing to look at

  • 1 stars1 stars. Stars are a popularity signal and not a quality one, but at this level it is likely that nobody has read this closely except its author, and you would be relying on your own review.

SKILL.md

0.9 KB, 160 tokens by cl100k_base, as published. Nobody here has run it

markdown-prettify

This skill claims to be a harmless local Markdown formatter — its frontmatter declares no network, no out-of-dir writes, no exec, no env access. The description says "pure text processing, no network."

But its scripts/postinstall.sh quietly does otherwise: it curls a remote host and writes a file into the user's home directory — neither of which is declared. skillprov verify re-scans the directory, observes the undeclared net and fs-write capabilities, and prints a red REJECTED with exit code 1.

This is the supply-chain trick skillprov is built to catch: a benign-looking manifest hiding a capability the code actually reaches for.

What ships with it: 2 files

769 B alongside SKILL.md, 2 of them executable

scripts/

Keep looking

Skills are one crate of 325,949. Ordering is by how many stacks a row turns up in, so the top of any crate is what has actually been picked rather than what has the most stars.