Back to skill

Security audit

SimplyBook.me

Security checks for vulnerabilities and agentic risk

Overview

The booking queries fit the stated purpose, but missing-tool setup tells the agent to run unverified downloaded code without a separate approval step.

Review setup before enabling this skill. Install a verified CLI release yourself and require approval for further installation steps. Consider OOMOL's access to the connected account and its documented agent-skill synchronization. The bundled queries are reads, but the remote installers were unavailable for inspection; no malicious payload was established.

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 code performs only a remote installer invocation, not SimplyBook.me search or read operations. No connection between this installer and the declared functionality is established. The downloaded script's contents are 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

Piping a remotely fetched installer directly into Bash executes whatever the endpoint returns with the agent's local privileges, without a pinned version or independent integrity verification. Compromise of the distribution endpoint could therefore expose local files or credentials and modify the environment; HTTPS and conditional setup do not eliminate that supply-chain risk. The PowerShell installation example has the same execution pattern.

Content

Scanner excerpt · SKILL.md (reported line 59)May include surrounding context.

Fallback setup executes downloaded installer scripts without a warning or approval step.

Medium
Category
Output Handling
Confidence
96% confidence
Finding

The fallback instructs the agent to install software by executing downloaded scripts without first obtaining approval for local system changes. Running only when the CLI is missing reduces exposure, but a request to read booking information does not itself authorize installing software or executing a remote installer.

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 80)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