T05 · Unauthorized Access and Privilege Escalation
- Location
SKILL.md:19- Finding
Excessive Tool Permissions for Diagram Generation
- Content
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Vulnerability Details
File Location:
SKILL.md, lines 19–22, with supporting capability declarations at lines 115 and 202–204
Vulnerability Type: Excessive filesystem and command-execution permissions
Risk Level: MediumVulnerable Code
yaml tools: - read - exec - writeSupporting declarations:
markdown - **Category**: MD+execute()markdown - **File processing**: Supports reading, parsing, and writing multiple file formats - **API integration**: Calls external services through standardized interfaces - **Command execution**: Executes system commands in a secure sandbox and collects resultsTechnical Analysis
The Skill's stated purpose is to generate Mermaid diagram source, which can ordinarily be returned directly as text without arbitrary command execution or unrestricted filesystem access. Nevertheless, the Skill requests
read,write, andexectools and advertises file processing, external API integration, and system-command execution.No specific commands, permitted arguments, filesystem boundaries, approved network destinations, or enforcement mechanisms are defined. The document recommends command allowlisting and sandboxing elsewhere, but it does not implement or specify such controls. Consequently, the declared capability set exceeds the minimum permissions needed for the stated task and creates a least-privilege violation if the hosting Agent grants these tools.
The audited file does not contain instructions that explicitly abuse these permissions. Exploitation therefore depends on the host granting the declared tools and on attacker-controlled or misinterpreted input causing the Agent to invoke them outside the legitimate diagram-generation workflow.
Attack Path
- A host loads the Skill and grants the declared
read,write, andexeccapabilities. - An attacker supplies diagram content containing adversarial instructions or content designed to be interpreted as operational Agent ins ...[truncated 1120 chars]
- A host loads the Skill and grants the declared
- Remediation
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Remediation Suggestions
- Remove
exec,read, andwritefrom the tool declaration when the Skill only needs to produce Mermaid source as model-generated text. - If image rendering is required, replace arbitrary
execaccess with a dedicated Mermaid-rendering tool that accepts validated diagram text and fixed rendering options. - If file export is required, grant only a narrowly scoped write operation restricted to a user-approved output directory. Prevent path traversal and reject absolute or parent-relative paths.
- Avoid unrestricted read access. Where input files are necessary, require explicit user selection and restrict reads to those approved files.
- Define an enforceable command allowlist, fixed executable path, permitted arguments, execution timeout, resource limits, and a sanitized environment if command execution cannot be removed.
- Require user confirmation before filesystem changes, command execution, or network access.
- Define approved API destinations and prohibit arbitrary outbound requests.
- Treat all user-supplied diagram content as untrusted data and prevent it from being interpreted as tool-use instructions.
- Ensure that sandboxing and least-privilege controls are implemented by the host rather than merely described in documentation.
- Remove