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Security audit

firstskill

Security checks for vulnerabilities and agentic risk

Overview

This skill is a disclosed generative-art helper with minor documentation and branding concerns, but no evidence of hidden access, persistence, exfiltration, or destructive behavior.

Before installing, understand that this skill creates browser-based generative art files and generated HTML may load p5.js and fonts from external CDNs. If you plan to publish or share outputs, review or remove the Anthropic-styled branding unless you have appropriate permission.

Vulnerability Patterns
  • 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
  • Unauthorized Access and Privilege EscalationObtains permissions beyond the task's legitimate needs
Vulnerability Patterns
  • 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
  • Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
Findings (2)

Intent-Code Divergence

Medium
Category
Not specified by scanner
Confidence
96% confidence
Finding

Early documentation states the skill outputs .md, .html, and .js files, implying separate artifacts. Later sections explicitly require embedding all JavaScript inline in one HTML file and say not to create separate .js files, which directly contradicts the earlier output description.

Content

No source excerpt is available for this finding.

Description-Behavior Mismatch

Medium
Category
Not specified by scanner
Confidence
91% confidence
Finding

The skill mandates copying a branded templates/viewer.html verbatim and preserving Anthropic branding exactly, while presenting the result as original algorithmic art. This creates a provenance and attribution risk: generated outputs may misleadingly imply official Anthropic authorship, endorsement, or a right to reuse branded UI assets, especially if shared externally.

Content

No source excerpt is available for this finding.

Static analysis

No suspicious patterns detected.