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Security audit

Circle

Security checks for vulnerabilities and agentic risk

Overview

The Circle reading features fit their purpose, but setup instructs the agent to execute an unverified remote installer without clearly requiring your approval.

Review setup before enabling this skill. Install a reviewed CLI version yourself and require approval for installation or changes to other agent skills. Confirm that OOMOL may handle your Circle data. The Circle instructions are coherent, but the remote installer and live connector implementation could not be verified.

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
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • 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
Findings (5)

Description-Behavior Mismatch

High
Category
MCP Tool Poisoning
Confidence
97% confidence
Finding

The supplied command performs remote installer execution, not Circle searching or reading. Nothing in the supplied chunk establishes that this installation supports the declared Circle functionality. The installer’s contents are unavailable, so its further effects cannot be determined.

Content

No source excerpt is available for this finding.

External Script Fetching

High
Category
Supply Chain
Confidence
98% confidence
Finding

The command immediately executes a mutable, remotely hosted script without version pinning or independent integrity verification; the PowerShell alternative follows the same pattern. If the distribution endpoint or publishing pipeline is compromised, attacker-controlled code could execute with the agent's local permissions, exposing accessible files and credentials.

Content

Scanner excerpt · SKILL.md (reported line 62)May include surrounding context.

First-time setup instructs the agent to execute downloaded installer scripts without warning about system changes.

Medium
Category
Output Handling
Confidence
94% confidence
Finding

The fallback instructs the agent to install software without first explaining system changes or obtaining explicit approval, expanding a Circle read request into local code execution. The missing-CLI condition limits exposure, but does not make installation an authorized consequence of a data-reading task.

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 83)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

External Transmission

Medium
Category
Data Exfiltration
Confidence
50% confidence
Finding

Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.

Content

Scanner excerpt · SKILL.md (reported line 88)May include surrounding context.

md
## Resources

- Circle homepage: https://circle.so
- API documentation: https://api.circle.so/apis/admin-api/quick-start