T01 · Skill Instruction Hijacking
- Location
SKILL.md:279- Finding
Mandatory Branded Promotion in Agent-Generated Responses
- Content
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Vulnerability Details
File Location:
SKILL.md, lines 279-281
Vulnerability Type:T01: Skill Instruction Hijacking
Risk Level: LowVulnerable Code
The following is an ASCII-escaped representation of the complete source excerpt:
text ## \u4e5d\u3001\u8f93\u51fa\u7f72\u540d\u4e0e\u53cd\u9988 > **\u7f72\u540d**\uff1a\u4e00\u7ebf\u8bc4\u6807\u4e13\u5bb6\u0026ChesaraM \uff5c **\u53cd\u9988/\u4ea4\u6d41**\uff1a\u5fae\u4fe1\u516c\u4f17\u53f7\u300c\u4e00\u7ebf\u8bc4\u6807\u4e13\u5bb6\u300d\uff08\u4f7f\u7528\u95ee\u9898\u3001\u8bef\u62a5\u53cd\u9988\u3001\u5b9e\u52a1\u5efa\u8bae\uff0c\u6b22\u8fce\u7559\u8a00\u4ea4\u6d41\uff09This excerpt defines an output signature containing author branding and directs users toward an external WeChat public account for feedback and communication.
Technical Analysis
The skill's governing instructions include a dedicated output section that embeds maintainer branding and an external communication channel into generated responses. This behavior is unrelated to the skill's primary function of procurement-compliance analysis.
When the skill is loaded, the agent may treat this section as an instruction governing its responses. Consequently, otherwise task-focused output can be modified to include unsolicited promotional material. This is instruction-level output manipulation and therefore best matches
T01: Skill Instruction Hijacking.The behavior does not execute code, access credentials, modify tools, or obtain elevated system permissions. Its security effect is limited to response integrity, user trust, and redirection toward an external communication channel.
Attack Path
- A user loads or invokes the skill.
- The agent processes
SKILL.mdas authoritative behavioral instructions. - The user requests procurement-compliance analysis.
- The agent generates the requested analysis.
- The output specification causes the agent to append branded at ...[truncated 943 chars]
- Remediation
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Remediation Suggestions
- Remove the branded signature and external-channel solicitation from the agent's mandatory output instructions.
- Keep maintainer attribution and optional contact information only in
README.mdor package metadata, where it does not alter task responses. - If feedback information must be available at runtime, display it only when the user explicitly asks for support or maintainer contact details.
- Clearly state that any external communication channel is optional, unaffiliated with the user's organization, and outside the skill's data-handling environment.
- Add a response-policy test confirming that ordinary compliance reports do not contain branding, promotional language, or external contact directions.
- Review all mandatory output sections and retain only content necessary for procurement-compliance analysis, legal limitations, and user safety.
