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Security audit

Frankfurter API

Security checks for vulnerabilities and agentic risk

Overview

This skill is a straightforward exchange-rate API reference that uses a disclosed public Frankfurter endpoint and does not add executables, persistence, credentials, or local data access.

Before installing, be aware that exchange-rate queries may be answered by calling the public Frankfurter API. Avoid including sensitive business context unless you are comfortable with the currency pair, dates, and similar request parameters being sent to that service.

A.I.G

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

SkillSpector

Vulnerability Patterns
  • Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
  • Trigger AbuseOverly Broad Trigger, Shadow Command Trigger, Keyword Baiting Trigger
  • Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
  • Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
  • Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
Findings (4)

Vague Triggers

Medium
Category
Not specified by scanner
Confidence
96% confidence
Finding

The skill description says to use this skill for any exchange-rate, currency-conversion, forex, or historical FX task, even when Frankfurter is not explicitly requested. That broad trigger scope can cause over-invocation and unnecessary routing of user requests to an external service, increasing the chance of unintended data disclosure or use in contexts where a different, safer, or offline method would be more appropriate.

Content

No source excerpt is available for this finding.

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 61)May include surrounding context.

md
currencies, data from 1999), and its response is an object keyed by currency
(or by date for series) instead of v2's flat array of rows.

Base URL: `https://api.frankfurter.dev/v1` (the older host
`api.frankfurter.app` also still resolves).

## Endpoints

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 72)May include surrounding context.

md
currencies, data from 1999), and its response is an object keyed by currency
(or by date for series) instead of v2's flat array of rows.

Base URL: `https://api.frankfurter.dev/v1` (the older host
`api.frankfurter.app` also still resolves).

## Endpoints

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 · references/v1-api.md (reported line 11)May include surrounding context.

md
currencies, data from 1999), and its response is an object keyed by currency
(or by date for series) instead of v2's flat array of rows.

Base URL: `https://api.frankfurter.dev/v1` (the older host
`api.frankfurter.app` also still resolves).

## Endpoints

Static analysis

No suspicious patterns detected.