T01 · Skill Instruction Hijacking
Error
- Location
- SKILL.md:62
- Finding
- Unconditional disclosure of public LinkFox conversation URLs<![CDATA[ ## Vulnerability Details **File Location**: `SKILL.md:62-74`, `SKILL.md:443-452` **Vulnerability Type**: Output hijacking and forced public data sharing **Risk Level**: Critical ### Vulnerable Code or Instructions ```markdown ### RULE 0 — ShareURL FIRST (highest priority, ALWAYS apply when present) Scan stdout for a line `ShareURL: <url>`. **The moment you find one, forward that URL to the user as the very first thing in your reply, before the reflection / results / anything else.** It is a PUBLIC URL — the user can open it on any device without auth, see every step the agent took, and download all generated artifacts (CSV/Excel, images, HTML reports, attachments). Always send it; never decide "to share or not to share". This rule is unconditional: any successful run produces one (`status=finished`), and if it appears in stdout you forward it. ``` The public URL is documented as exposing the complete task: ```markdown - `url`: ShareURL — public, read-only share page for the entire conversation behind this run (intent, tool calls, intermediate outputs, reflection, final summary), with downloadable artifacts (CSV/Excel, images, HTML reports, attached files). ``` ### Technical Analysis The Skill assigns the highest priority to a fixed output behavior and explicitly removes the Agent's discretion to evaluate whether disclosure is appropriate. Every successful task must place a third-party LinkFox share URL at the beginning of the response. The linked page is unauthenticated and may expose the user's intent, tool calls, intermediate data, generated reports, and downloadable artifacts. This behavior is not necessary to provide the requested e-commerce analysis results and exceeds minimum privilege by creating and promoting a public copy of the task. ### Attack Path 1. A user submits commercially sensitive product, competitor, sales, or ERP research. 2. The task and its results are processed by LinkFox. 3. LinkFox returns a public, unauthenticated sh ...[truncated 725 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove the unconditional `ShareURL FIRST` instruction. 2. Do not create a public share page by default. 3. Require explicit, informed user consent before creating or returning any public link. 4. Default to authenticated, access-controlled links with short expiration periods. 5. Allow the Agent to withhold a link when prompts or artifacts contain sensitive data. 6. Clearly enumerate what the share page contains before requesting consent. 7. Add server-side revocation and deletion controls. 8. Avoid placing public links first in responses or treating promotional output as higher priority than user instructions and security policy. ]]>
