T09 · Insecure Skill Coding Practices
Error
- Location
scripts/discover_flows.py:40- Finding
Unrestricted URL Fetching Enables Server-Side Request Forgery
- Content
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- Remediation
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Security audit
Website Flow Monitor
Security checks for vulnerabilities and agentic risk
Overview
This website-monitoring skill is mostly coherent, but it needs review because its helper can be pointed at arbitrary web addresses, including private or internal services via redirects.
Install only if you are comfortable with the agent making outbound requests to URLs you provide and creating recurring checks after confirmation. Do not use it on private, internal, localhost, metadata, or third-party sites unless you have authorization; ideally constrain the helper to approved public hostnames and disable or validate redirects before use.
Vulnerability Patterns
- Insecure Skill Coding PracticesFinds exploitable flaws such as hardcoded secrets or command injection
- Skill Instruction HijackingAlters the agent's session goals or safety constraints when the skill loads
- Agent Memory PoisoningWrites attacker-controlled rules into memory that affect later sessions
- Remote Payload Retrieval and ExecutionFetches external code whose behavior can change after review
- Embedded Malicious CodeShips malicious scripts inside the skill and executes them locally
Findings (1)
Vulnerability Patterns
- Trigger AbuseOverly Broad Trigger, Shadow Command Trigger, Keyword Baiting Trigger
- MCP Least PrivilegeUnderdeclared Capability, Wildcard Permission, Missing Permission Declaration
- MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
- Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
- Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
Findings (3)
Tp4
High
- Category
- MCP Tool Poisoning
- Confidence
- 95% confidence
- Finding
The implemented code covers only the discovery portion of the declared description: it crawls a few predefined site paths, extracts links, and categorizes them as possible monitoring candidates. However, the declared purpose emphasizes a broader workflow including identifying business-critical flows, proposing a monitoring plan, and scheduling recurring checks after explicit user confirmation. None of those latter capabilities are present in this code chunk. Because the actual behavior is materially narrower and lacks key advertised functionality, this is a description-behavior mismatch.
- Content
Undeclared Tool Scope
Medium
- Category
- MCP Least Privilege
- Confidence
- 86% confidence
- Finding
The skill instructs the agent to scan websites and use a discovery script, which implies network-capable behavior, but it does not declare an explicit tool scope such as allowed network access. Undeclared capabilities weaken policy enforcement and reviewability, increasing the chance that the skill is invoked with broader access than intended or performs external requests without clear user/admin visibility.
- Content
Vague Triggers
Medium
- Category
- Not specified by scanner
- Confidence
- 94% confidence
- Finding
The description uses broad trigger language such as monitoring a website, checking uptime, designing checks, and automating recurring checks, which can cause the skill to activate in loosely related contexts. Over-broad invocation increases the risk of unintended network reconnaissance or premature automation behavior on external sites when a narrower, more specific skill should have been selected.
- Content