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Security audit

Nango

Security checks for vulnerabilities and agentic risk

Overview

The Nango integration is coherent, but automatic software installation and insufficient safeguards around credential-returning reads warrant review.

Review and install the CLI separately before allowing this workflow, including its effects on other installed agent skills. Give OOMOL a narrowly scoped Nango key, exclude credential-reading permissions unless needed, and treat returned connection details as potentially secret. Keep the required approvals for writes and deletions. Remote installer and hosted backend behavior were not verified; 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 (5)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
99% confidence
Finding

The supplied command installs software from an Oomol domain and contains no Nango operations or evidence that this installation supports Nango. Its visible behavior therefore materially differs from the declared purpose. The downloaded script is not supplied, so its additional effects cannot be determined.

Content

No source excerpt is available for this finding.

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
84% confidence
Finding

The supplied chunk only initiates an oo login and contains no Nango-specific operations or configuration. Authentication could support a Nango integration, but no connection between this CLI and Nango is established in the supplied material.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

The command pipes a remotely fetched, mutable script directly into Bash without pinning or independent integrity verification; the PowerShell alternative follows the same pattern. If the distribution endpoint or release process is compromised, the installer can execute arbitrary code with the invoking user's permissions, potentially exposing local credentials and files. HTTPS and the conditional setup path reduce some exposure but do not establish the script's integrity.

Content

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

The setup workflow executes downloaded installer scripts without warning about local code execution and system changes.

Medium
Category
Output Handling
Confidence
90% confidence
Finding

The missing-CLI fallback instructs the agent to execute a downloaded installer without first obtaining approval for local software installation or explaining its system effects. This expands an ordinary Nango task into local code execution; making installation conditional reduces exposure but does not establish user consent.

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