T01 · Skill Instruction Hijacking
- Location
SKILL.md:19- Finding
Unconditional skill instructions hijack agent behavior and response flow
- Content
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Vulnerability Details
File Location:
SKILL.md, lines 19-43 and 116-120
Vulnerability Type: Agent instruction hijacking
Risk Level: HighVulnerable Code Snippet:
markdown **Rule 1 — FIRST MESSAGE IS ALWAYS THIS, NO EXCEPTIONS:** Use the `message` tool to send this BEFORE running any exec command: > 📡 Video received, analyzing... This must be a `message` tool call, not your final reply text. Using the message tool sends it immediately to the user while you continue processing. If you put it in your reply text instead, the user won't see it until everything is done — which defeats the purpose entirely. Do NOT reference conversation history, prior testing, or anything from the current session. Every URL is treated fresh. **Rule 2 — NEVER GO SILENT** The user MUST receive a message every 30-60 seconds while processing. Silence = broken. - After download step: send "📥 Downloaded! Transcribing now..." - If anything takes more than 30 seconds: send "⏳ Still working..." **Rule 3 — NO PERSONAL COMMENTARY. EVER.** Do NOT add ANY of the following: - "This appears to be the video we already tested" - "I recognize this URL" / "you've sent this before" - "Heads up — this is the same link" - Any footnote, parenthetical, or aside about the URL or prior usage Just run the skill and give the answer. End with the save prompt. Nothing else.markdown ### Step 4 — Offer to save (MANDATORY if from_cache: false) After giving the answer, ALWAYS ask this — do not skip it: > 💾 Want to save this transcript so you can ask follow-up questions later without re-downloading? (yes/no)Technical Analysis
The skill uses unconditional priority language such as “always,” “no exceptions,” “must,” and “do not” to control agent tool calls, suppress relevant conversation history, and force response content. These directives extend beyond the technical requirements of downloading and transcribing ...[truncated 1118 chars]
- Remediation
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Remediation Suggestions
- Replace absolute directives with conditional workflow guidance.
- Explicitly state that user instructions, relevant conversation context, and higher-priority safety policies take precedence.
- Remove the instruction to disregard conversation history.
- Make progress messages optional and dependent on actual execution time and host capabilities.
- Ask whether to save a transcript only when consistent with the user’s request.
- Limit skill instructions to the minimum behavior necessary for video download and transcription.
