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Security audit

Youzan

Security checks for vulnerabilities and agentic risk

Overview

The Youzan lookup features fit their purpose, but setup can execute downloaded software without first asking for approval.

Review and approve CLI installation separately before allowing setup, including any bundled agent-skill changes. Connect only the intended Youzan shop and consider the sensitive business data accessible through OOMOL. The external installer and live connector implementations were not verified.

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
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
  • Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
  • Output HandlingUnvalidated Output Injection, Cross-Context Output, Unbounded Output
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
Findings (4)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
98% confidence
Finding

The supplied command invokes a remote installer; it contains no visible Youzan search or read functionality. Nothing in the provided material establishes this installer as a supporting dependency for the declared purpose. The downloaded script is not supplied, so its specific effects cannot be determined.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

The command pipes a mutable remote script directly into Bash without checking a pinned digest or signature; the PowerShell alternative has the same execution pattern. Compromise of the distribution endpoint or its delivery pipeline could execute attacker-controlled code with the agent's local privileges, potentially exposing files and credentials. HTTPS and the missing-CLI prerequisite reduce some exposure but do not establish artifact integrity.

Content

Scanner excerpt · SKILL.md (reported line 63)May include surrounding context.

The fallback setup instructs the agent to execute downloaded installer scripts without warning the user about running remote code on their machine.

Medium
Category
Output Handling
Confidence
94% confidence
Finding

When the CLI is missing, the skill directs the agent to execute a remotely supplied installer without first obtaining explicit approval for local software installation. The error-triggered fallback limits exposure, but a read-oriented Youzan request can still lead to local code execution and system changes beyond the user's apparent task.

Content

No source excerpt is available for this finding.

Autonomous Decision Making

Medium
Category
Excessive Agency
Confidence
80% confidence
Finding

Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.

Content

Scanner excerpt · SKILL.md (reported line 84)May include surrounding context.

md
- **`OOMOL_INSUFFICIENT_CREDIT`** — OOMOL billing stop. Recharge at `https://console.oomol.com/billing/token-recharge` before retrying.

- **HTTP 402 without `OOMOL_INSUFFICIENT_CREDIT`** — the third-party account itself has no active plan or credit. Report the provider error message as is; do not ask the user to recharge OOMOL.

## Resources