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Security audit

MSG91

Security checks for vulnerabilities and agentic risk

Overview

The MSG91 workflow is coherent, but its setup fallback executes changeable remote code without a clear approval or verification step.

Review the setup fallback before installing. Prefer a separately approved, verified CLI release and review its automatic skill synchronization. OOMOL will process MSG91 requests through your connected account; confirm recipients and message contents before sending. The remote installer contents were unavailable for inspection, so their precise local effects remain uncertain.

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
95% confidence
Finding

The visible behavior is remote installer execution rather than MSG91 data access or modification. Although installation can be a supporting implementation detail, the supplied content establishes no connection between this Oomol installer and MSG91 functionality. The downloaded script is not provided, so its further behavior 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 mutable remote installer directly into bash executes its contents with the agent process's local privileges, without prior review or integrity verification. The domain is consistent with the documented CLI provider and installation is conditional, but compromise of the distribution endpoint could still enable local data theft or modification; the PowerShell example has the same underlying risk.

Content

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

The setup fallback executes remotely downloaded installation scripts without warning about local system changes or remote-code execution.

Medium
Category
Output Handling
Confidence
94% confidence
Finding

The fallback directs installation of local software without explaining that it executes remote code or requiring approval for system changes. Restricting installation to a missing-CLI error reduces exposure, but authorization to perform a MSG91 operation does not necessarily authorize installing software.

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 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