T09 · Insecure Skill Coding Practices
Error
- Location
webhooks.md:96- Finding
Webhook Events Are Acknowledged Before Durable Processing
- Content
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- Remediation
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Security audit
Billing
Security checks for vulnerabilities and agentic risk
Overview
This is a coherent billing-integration guidance skill, but it includes copyable high-impact payment examples with insufficient guardrails and a few unsafe financial implementation patterns.
Review the examples before using this skill in production billing work. Use Stripe/Paddle test mode first, require explicit approval before actions that charge, refund, send invoices, alter subscriptions, or update connected accounts, and replace the unsafe webhook, refund, and floating-point billing examples with durable, audited, integer-money implementations.
Vulnerability Patterns
- Insecure Skill Coding PracticesFinds exploitable flaws such as hardcoded secrets or command injection
- 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
Findings (4)
T09 · Insecure Skill Coding Practices
Note
- Location
webhooks.md:102- Finding
Webhook Endpoint Reflects Internal Exception Messages
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T09 · Insecure Skill Coding Practices
Error
- Location
marketplace.md:98- Finding
Marketplace Split-Refund Example Returns Only Half of the Requested Refund
- Content
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T09 · Insecure Skill Coding Practices
Warning
- Location
usage-billing.md:110- Finding
Usage Billing Performs Monetary Calculations with Floating-Point Values
- Content
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Vulnerability Patterns
- Data ExfiltrationExternal Transmission, Env Variable Harvesting, File System Enumeration
- Excessive AgencyUnrestricted Tool Access, Autonomous Decision Making, Scope Creep
- Prompt InjectionInstruction Override, Hidden Instructions, Exfiltration Commands
- Privilege EscalationExcessive Permissions, Sudo/Root Execution, Credential Access
- Supply ChainUnpinned Dependencies, External Script Fetching, Obfuscated Code
Findings (6)
Natural-Language Policy Violations
Medium
- Category
- Not specified by scanner
- Confidence
- 98% confidence
- Finding
Line L102 contains instructional content in Spanish while the rest of the skill is in English. This introduces a language/locale inconsistency without any user opt-in or documented reason, which can violate language policy expectations and reduce accessibility for users expecting a single language.
- Content
Autonomous Decision Making
Medium
- Category
- Excessive Agency
- Confidence
- 75% 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
md ### Operational Errors - Sending payment reminders during contractual grace period - Dunning without checking for open disputes → double loss - Proration without specifying mode → unexpected customer charges - Refunding without checking for existing chargeback → paying twice
Autonomous Decision Making
Medium
- Category
- Excessive Agency
- Confidence
- 75% 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
md ### Operational Errors - Sending payment reminders during contractual grace period - Dunning without checking for open disputes → double loss - Proration without specifying mode → unexpected customer charges - Refunding without checking for existing chargeback → paying twice
Missing User Warnings
Medium
- Category
- Not specified by scanner
- Confidence
- 93% confidence
- Finding
This markdown file includes example onboarding code that updates an account with personally sensitive information such as
ssn_last_4and even notes that a full SSN may be collected. The surrounding documentation does not warn readers about privacy, secure handling, or compliance obligations when collecting this data.- Content
Missing User Warnings
Medium
- Category
- Not specified by scanner
- Confidence
- 90% confidence
- Finding
This markdown file provides copyable Stripe examples that create checkout sessions, confirm off-session payment intents, create subscriptions, apply coupons, and finalize/send invoices, all of which can affect customer billing and account state. The document does not include any user-facing warning that these actions may create charges, alter subscriptions, or send invoices if run against live data.
- Content
Missing User Warnings
Medium
- Category
- Not specified by scanner
- Confidence
- 91% confidence
- Finding
In this markdown file, the embedded code example performs a network request to an external government API and includes the VAT number in the request body. The surrounding documentation does not warn that entered VAT identifiers and related data will be transmitted off-system, which is relevant to privacy and compliance expectations.
- Content