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Security audit

Nylas

Security checks for vulnerabilities and agentic risk

Overview

The Nylas read workflow is coherent, but automatic setup executes unverified remote code and leaves broader installation effects unclear.

Review and verify the CLI installation before allowing automatic setup, including whether it installs or updates other agent skills. Connect only the intended Nylas account with necessary permissions. The complete bundled artifact was inspected, but remote installer behavior and server-side credential handling remain unverified.

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
  • MCP Tool PoisoningHidden Instructions, Unicode Deception, Parameter Description Injection
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
Findings (4)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
98% confidence
Finding

The supplied code contains no Nylas operations; its sole behavior is downloading and executing an Oomol installer. Nothing supplied establishes that this installation supports the declared Nylas functionality. The installer's downstream actions cannot be determined from this chunk.

Content

No source excerpt is available for this finding.

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
85% confidence
Finding

Authentication could support a Nylas integration, but the supplied chunk contains only a login command, with no demonstrated Nylas connection or data-access behavior. As supplied, its primary behavior does not match the declared purpose. The command alone does not establish which service or account is accessed.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

The setup instructions pipe a remotely fetched, unpinned script directly into Bash without verifying its integrity or reviewing its contents; the PowerShell alternative has the same execution pattern. Compromise of the installer endpoint or its delivery infrastructure could execute arbitrary code with the agent process's local permissions, exposing files and credentials. The missing-CLI condition limits when this occurs, and the vendor domain is contextually appropriate, but neither protects against a compromised installer.

Content

Scanner excerpt · SKILL.md (reported line 58)May include surrounding context.

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 79)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