T05 · Unauthorized Access and Privilege Escalation
- Location
SKILL.md:21- Finding
Excessive Tool Permissions for a Weather Skill
- Content
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Vulnerability Details
File Location:
SKILL.md:21-24
Vulnerability Type: Excessive tool scope and violation of least privilege
Risk Level: MediumVulnerable Code
yaml tools: - read - exec - writeTechnical Analysis
The skill declares unrestricted file-reading, file-writing, and command-execution tools even though its stated purpose is to retrieve weather information. A weather lookup should only require narrowly scoped network access to an approved weather service.
The document does not define command allowlists, filesystem path restrictions, trusted weather endpoints, argument validation, or enforceable sandbox controls. Although later text claims that commands execute in a safe sandbox, no implementation or configuration is present to enforce that claim.
Consequently, an Agent loading this skill may grant capabilities unrelated to its legitimate purpose. The issue is a least-privilege violation rather than evidence of an embedded malicious payload: the audited project contains only
SKILL.mdand no executable scripts.Attack Path
- An Agent loads the weather skill and grants the declared
read,write, andexectools. - The skill accepts a user-provided instruction as its primary input.
- A malicious or manipulated instruction requests an operation unrelated to weather, such as reading a local file, modifying a writable file, or executing a system command.
- Because the skill defines no enforceable command allowlist, path restriction, or operation-level authorization check, the Agent may invoke the excessive tools.
- The operation executes with the permissions already available to the Agent process.
This path is conditional on the host Agent granting and honoring the declared tools. The file does not itself contain commands that actively exploit these permissions.
Impact Assessment
Successful abuse could provide access to the capabilities of the hosting Agent process, including:
- Reading files acce ...[truncated 514 chars]
- An Agent loads the weather skill and grants the declared
- Remediation
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Remediation Suggestions
- Remove
read,write, andexecfrom the declared tool list because they are not required for weather retrieval. - Replace them with a narrowly scoped HTTPS request tool restricted to explicitly approved weather-service domains.
- Permit only required HTTP methods and reject redirects to unapproved hosts.
- Validate location, date, language, and forecast-range parameters against strict schemas before making requests.
- Prevent user input from being interpreted as a command, file path, URL, shell fragment, or additional Agent instruction.
- If command execution is genuinely required, document the exact commands and arguments, enforce an immutable allowlist, avoid shell invocation, and run the operation in a restricted sandbox with minimal filesystem and network access.
- If file access is genuinely required, constrain it to a dedicated application directory and prohibit traversal, absolute paths, symbolic-link escapes, and access to credentials or configuration files.
- Add explicit authorization checks before sensitive tool calls and require user confirmation for operations outside weather retrieval.
- Align the documentation with the actual implementation, including resolving the contradictory statements about whether an API key is required.
- Add security tests verifying that weather prompts cannot trigger local file access, file modification, or arbitrary command execution.
- Remove