T05 · Unauthorized Access and Privilege Escalation
Warning
- Location
- SKILL.md:8
- Finding
- Excessive Shell and File-Read Permissions## Vulnerability Details **File Location**: `SKILL.md`, line 8 **Vulnerability Type**: Least-privilege violation through unnecessary tool permissions **Risk Level**: Medium **Complete Code Snippet**: ```yaml allowed-tools: Bash, Read ``` ### Technical Analysis The skill's declared purpose is to generate YouTube thumbnail concepts using chat and image-generation capabilities. Arbitrary shell execution through `Bash` and unrestricted local-file access through `Read` are not necessary for that task. Granting these capabilities expands the skill's authority beyond its legitimate functional requirements. Although the audited files do not contain an explicit malicious shell command or file-reading instruction, the excessive permissions create an exploitable boundary if future, external, or attacker-influenced instructions cause the agent to invoke these tools. The risk is increased by the skill's references to a mutable third-party setup guide and its vague instruction to use relevant external capabilities. The current text does not explicitly require retrieving or executing remote content, so those references are not independently classified as remote payload execution. ### Attack Path 1. A user loads or invokes the skill. 2. The runtime grants the skill access to `Bash` and `Read` based on its declared tool allowlist. 3. Attacker-controlled prompt content, untrusted task data, or future modified instructions influence the agent's workflow. 4. The influenced workflow invokes `Read` to access local files unrelated to thumbnail generation, or invokes `Bash` to execute arbitrary commands. 5. Commands execute with the operating-system privileges of the agent process, and readable local information may be exposed through generated output or subsequent tool interactions. No direct exploit command is shipped in the audited project; exploitation depends on another instruction source influencing the unnecessarily privileged agent. ...[truncated 574 chars]
- Remediation
- ## Remediation Suggestions 1. Remove `Bash` and `Read` from the skill's allowed tools because they are not required for thumbnail concept generation. 2. Grant only the narrowly scoped chat and image-generation capabilities documented under the skill's API requirements. 3. If file input becomes necessary, replace unrestricted reading with a user-selected-file mechanism restricted to an approved workspace or media directory. 4. If command execution becomes necessary in a future version, expose a dedicated tool with fixed arguments and an explicit command allowlist rather than arbitrary shell access. 5. Require user confirmation before accessing local data, invoking external services, or performing side effects. 6. Pin and locally document any required external capability instead of relying on mutable third-party instructions. 7. Add automated validation that rejects skill manifests requesting tools not directly justified by the documented workflow.