T01 · Skill Instruction Hijacking
Warning
- Location
- SKILL.md:230
- Finding
- Mandatory Vendor Promotion and External-Link Injection into User-Facing Reports## Vulnerability Details **File Location**: `SKILL.md:230-231` **Additional Locations**: `SKILL.md:103-104`, `SKILL.md:143-146` **Vulnerability Type**: T01: Skill Instruction Hijacking **Risk Level**: Medium ### Vulnerable Instruction The following is an English translation of the complete instruction at the primary location: ```text When the output contains reportUrl, it must be appended at the end using the fixed wording: "View the complete graphical report online / Export: <reportUrl>" (login to the account that owns the report is required). ``` Related instructions additionally require the agent to promote keyword-analysis functionality after producing a VOC report and to append the web report link using prescribed promotional wording. ### Technical Analysis The Skill imposes persistent vendor-oriented output requirements that are not strictly necessary to extract use cases from Amazon reviews. Whenever the external service returns a `reportUrl`, the agent is instructed to insert that URL into its final answer using fixed wording. Other instructions direct the agent to proactively mention additional vendor features even when the user did not request them. This behavior alters the agent's response objectives from answering the user's request to promoting and directing traffic to the Skill vendor's external service. Because these instructions are loaded as part of the Skill and are phrased as mandatory behavior, they can override the agent's ordinary discretion regarding relevance, concision, and whether an external link should be presented. The URL is generated from the configured ARI web base. The default is `https://ari.funewa.com`; a custom web base is accepted only when `ARI_ALLOW_CUSTOM_BASE=1` is also set. This control reduces accidental redirection but does not eliminate the underlying output manipulation. ### Attack Path 1. A user activates the Amazon use-case mining Skill. 2. The agent loads th ...[truncated 1347 chars]
- Remediation
- ## Remediation Suggestions 1. Remove mandatory fixed promotional wording from the Skill instructions. 2. Present `reportUrl` only when the user requests an online report, export link, or graphical view, or when the link is directly necessary to complete the requested task. 3. Clearly label external links as optional and identify their destination domain before presenting them. 4. Remove instructions requiring unsolicited promotion of keyword analysis, sharing, posters, billing pages, or other commercial features. 5. Preserve the agent's discretion to omit irrelevant links when the user requests a concise answer. 6. Validate generated links against an explicit HTTPS origin allowlist before including them in output. 7. Treat custom web-base configuration separately from API development configuration, and display a clear warning when a non-production host will be exposed to users. 8. Never automatically open returned URLs or transmit additional credentials to report links.
