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Security audit

DeepL

Security checks for vulnerabilities and agentic risk

Overview

The DeepL workflow fits its purpose, but setup executes unverified remote code and leaves broader changes to agent skills uncontrolled.

Review and install a verified CLI release yourself before use, and check or disable automatic synchronization of other agent skills. Translation text passes through OOMOL to DeepL and may consume paid quota. The bundled instructions were fully inspected, but the remote installer and server-side credential handling remain unverified; no malicious intent 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
97% confidence
Finding

The only visible operation is remote installer execution, rather than the declared DeepL functionality. Dependency installation can be a supporting implementation detail, but the supplied chunk does not establish that this installer supports DeepL. The downloaded script is not provided, 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
94% confidence
Finding

The supplied chunk only invokes a login command; it does not search or read DeepL data or visibly identify DeepL as the authentication target. Authentication could support an integration, but the supplied code does not establish that connection and contains none of the declared functionality.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

The fallback pipes a remotely fetched, unpinned installer directly into Bash without integrity verification or review; the PowerShell alternative uses the same download-and-execute pattern. If the distribution endpoint or delivery chain is compromised, attacker-controlled code could execute with the agent's local privileges and access available files or credentials; limiting installation to a missing-CLI error reduces exposure but does not eliminate it.

Content

Scanner excerpt · SKILL.md (reported line 57)May include surrounding context.

The action workflow permits sending translation text to external services without a privacy warning.

Medium
Category
Output Handling
Confidence
91% confidence
Finding

The workflow instructs the agent to execute connector actions and declares all untagged actions safe to run directly, including translate_text. Although the skill identifies OOMOL and DeepL, it does not warn that translation payloads leave the user's environment and may contain sensitive or confidential information.

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 78)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