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Security audit

Paymo

Security checks for vulnerabilities and agentic risk

Overview

Paymo changes require approval, but the missing-software fallback executes remote installers without clearly obtaining permission for broader local changes.

Review and install oo yourself before enabling this skill, and check its automatic agent-skill installation settings. Keep the required approvals for Paymo changes and deletions. OOMOL handles the connected Paymo credentials and request data. The remote installers and server-side connector implementation were unavailable for verification.

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
96% confidence
Finding

The visible behavior is remote installer execution rather than Paymo data management. Although dependency installation can be a supporting implementation detail, the supplied chunk establishes no relationship between this installer and Paymo functionality. The downloaded script's contents and further effects are not available for assessment.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

Piping a remotely fetched, unpinned installer directly into bash executes its contents with the invoking user's privileges, without an integrity check or review opportunity. Compromise of the distribution endpoint could therefore lead to local code execution and access to user-readable secrets; HTTPS and the legitimate dependency relationship do not eliminate this supply-chain risk. The PowerShell fallback has the same underlying issue.

Content

Scanner excerpt · SKILL.md (reported line 70)May include surrounding context.

Fallback installation executes downloaded scripts without warning about their system-level effects.

Medium
Category
Output Handling
Confidence
94% confidence
Finding

The missing-command fallback instructs the agent to install software without first explaining the local changes or obtaining explicit installation approval. Although this is a legitimate dependency and the fallback is conditional, authorizing a Paymo task does not necessarily authorize executing an installer that can modify the local environment.

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 91)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