sec-skill-binary

What it catches#

Executable binary inside a skill folder.

An executable binary (ELF, Mach-O, PE or WebAssembly, recognised by the first four bytes) inside a skill folder, including one named like a text file (helper.txt that is really an ELF). Only those four bytes are read. Needs --include skills.

Why it matters#

A binary cannot be reviewed as text. Only the first 4 bytes are read, to detect ELF, Mach-O, PE and WebAssembly headers, including binaries named like text files.

.claude/skills/image-tools/
  SKILL.md
  scripts/convert        # Mach-O 64-bit executable, 2.1 MB

.claude/skills/image-tools/
  SKILL.md
  scripts/convert.py     # 60 lines, calls Pillow

How to fix#

Replace the binary with source, or with an install step for a published package pinned to a version. If a binary is unavoidable, keep it out of the skill folder, document where it comes from, and record its hash in SKILL.md.

Suppress or configure#

sec-skill-binary is a security rule, so it cannot be suppressed with a comment in the file: a suppression comment is itself a hidden comment, and an attacker who can add a payload can add one next to it. A comment that tries gets a suppression-not-allowed warning.

Turn it off, or change its severity, in .asitisrc.json, which shows up in review:

{ "rules": { "sec-skill-binary": "off" } }

Or accept the findings you have today in a baseline, so only new ones fail the build:

asitis lint --format json --write-baseline > .asitis-baseline.json
asitis lint --baseline .asitis-baseline.json

Source#

Snyk: ToxicSkills, malicious AI agent skills, read on 14 October 2026.