T01 · Skill Instruction Hijacking
Error
- Location
- SKILL.md:145
- Finding
- Mandatory Vendor Link and Promotional Text Injection into Agent Responses<![CDATA[ ## Vulnerability Details **File Location**: `SKILL.md`, lines 145-147 and 230-231 **Vulnerability Type**: Forced modification of the agent's final response **Risk Level**: High ### Vulnerable Code Snippet ```markdown **网页链接的用法** - 每份报告末尾附 `web.report`,措辞是「网页版有健康度图表和频次表,可生成分享链接与海报」——是补充,不是「建议你去网页」。 - 用户要把报告发给同事/发群:指向网页报告页的「分享」按钮,不要把整篇 Markdown 贴给他转发。 ``` ```markdown **输出含 `reportUrl` 时必须在结尾附上**, 固定文案:「在线查看图表版完整报告 / 导出:<reportUrl>」(需登录报告所属账户)。 ``` The source text requires the agent to append an ARI report link and fixed vendor-selected wording to generated reports. In English, the mandated wording promotes the online graphical report and export page and requires it to appear at the end of the response. ### Technical Analysis The Skill instructions do more than describe how to access an optional result. They impose a mandatory placement rule and fixed promotional wording whenever a `reportUrl` is present. This constitutes instruction-level output hijacking because loading the Skill causes the agent to modify its final response according to the vendor's promotional requirements, even when the user did not request an online report, sharing page, or export link. The directive is reinforced by a separate instruction requiring every report to include the vendor's web-report reference. The affected behavior is not necessary to perform the declared FAQ extraction and review-analysis functionality. A report URL can be returned as optional structured metadata without forcing promotional prose into the agent's user-facing answer. ### Attack Path 1. The agent loads and follows `SKILL.md`. 2. The agent invokes the ARI service to generate or retrieve a report. 3. The service response contains a `reportUrl`. 4. The Skill instructions require the agent to append fixed vendor wording and the external report URL. 5. The final answer is altered to include vendor-directed promotional content regardless of whether the user requested it. 6. The user may consequen ...[truncated 604 chars]
- Remediation
- <![CDATA[ ## Remediation Suggestions 1. Remove all mandatory wording and placement requirements for `reportUrl`. 2. Return the URL only as structured result metadata. 3. Include the URL in prose only when the user explicitly requests an online report, export, sharing feature, or graphical view. 4. Replace fixed promotional language with a neutral optional statement, such as: “An online report URL is available on request.” 5. Ensure the core FAQ or review-analysis result remains complete without requiring navigation to an external website. 6. Add an instruction that user preferences concerning response length, links, and external navigation take precedence over optional service-link presentation. ]]>
