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Security audit

Shorten.REST

Security checks for vulnerabilities and agentic risk

Overview

The Shorten.REST workflow is coherent, but setup can execute unchecked downloads and the required CLI can change other agents’ installed skills without clear disclosure.

Review and install a fixed CLI release yourself before use. The publisher documents OO_SKILLS_SYNC_DISABLED=1 to prevent startup synchronization into other agents’ skill directories. Confirm that OOMOL may process your Shorten.REST requests and retain the skill’s approval requirements for changes and deletions. The remote installer contents and exact installed release could not be 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 (5)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
98% confidence
Finding

The supplied command installs software from an Oomol endpoint rather than performing any visible Shorten.REST operation. Nothing in the provided code establishes that this installation is a supporting requirement for the declared purpose. The remote script's contents are unavailable, so its further behavior cannot be determined.

Content

No source excerpt is available for this finding.

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
86% confidence
Finding

Authentication could be a supporting implementation detail, but the supplied chunk consists entirely of a login command, with no Shorten.REST reference or data-operation workflow establishing that connection. Its demonstrated purpose therefore differs materially from the declared purpose.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

Piping the HTTPS response directly into bash executes mutable remote content without first verifying its integrity or reviewing it. The endpoint is relevant to the required CLI, but a compromised distribution source could still run arbitrary commands with the user's privileges; this is the same underlying installation risk flagged by SQP-2.

Content

Scanner excerpt · SKILL.md (reported line 60)May include surrounding context.

Fallback setup executes downloaded installer scripts without warning about local system changes or remote code execution.

Medium
Category
Output Handling
Confidence
94% confidence
Finding

The fallback directs execution of remotely downloaded shell or PowerShell code without an explicit installation approval step or integrity verification. If the installer source is compromised, code could execute with the invoking user's privileges; limiting installation to a missing-CLI error reduces exposure but does not remove the risk.

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 81)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