T09 · Insecure Skill Coding Practices
- Location
SKILL.md:208- Finding
Unsafe Disclosure of Sensitive Banking Information to Transaction Participants
- Content
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Vulnerability Details
File Locations:
SKILL.md:208references/negotiation-playbook.md:41
Vulnerability Type: Sensitive financial information exposure
Risk Level: MediumVulnerable Code Snippets
SKILL.md:208:markdown - Bring a screenshot of the bank application balance to give the agent and seller “certainty.”references/negotiation-playbook.md:41:markdown - Prepare a “certainty signal”: a bank application balance screenshot or proof of funds.The snippets above are faithful English translations of the affected instructions.
Technical Analysis
The Skill explicitly recommends showing a bank application balance screenshot to a real-estate agent and seller. A banking screenshot may expose substantially more information than is required to demonstrate purchasing capability, including:
- The buyer's available balance and broader financial position
- Account holder identity or partially displayed account identifiers
- Bank and account-product information
- Recent transaction details
- QR codes, device notifications, or other information visible on the screen
- Information that can be retained, redistributed, or combined with data from other sources
The instructions do not require redaction, recipient verification, secure transmission, limited retention, or minimum necessary disclosure. They also do not distinguish an official, purpose-limited proof-of-funds document from an unrestricted banking application screenshot.
This is an insecure information-handling practice under
T09: Insecure Skill Coding Practices. Although the Skill does not itself extract or transmit banking data, it directs the user to expose sensitive financial information to parties who do not need unrestricted access to it.Attack Path
- A buyer follows the Skill's negotiation instructions.
- The buyer opens a banking application and captures a s ...[truncated 1389 chars]
- Remediation
View remediation
Remediation Suggestions
-
Remove all recommendations to display or transmit a banking application balance screenshot.
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Prefer an official and purpose-limited proof-of-funds letter, mortgage pre-approval, or escrow confirmation issued by a verified financial institution.
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Disclose only the minimum amount necessary to establish that sufficient funds are available.
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If documentary evidence must be shared, require redaction of:
- Full and partial account numbers
- Transaction history
- Unnecessary balances
- QR codes and barcodes
- Customer identifiers
- Device notifications
- Authentication or session information
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Verify the recipient's identity and authority before sharing financial documentation.
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Use a secure, access-controlled transfer channel rather than ordinary messaging applications.
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State that recipients must not retain or redistribute the document beyond the transaction-verification purpose.
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Replace the affected instructions with guidance such as:
markdown Use a mortgage pre-approval or redacted, purpose-limited proof-of-funds document. Do not share banking application screenshots, account identifiers, transaction history, or balances exceeding the amount that must be demonstrated.
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