create-python-x402-facilitator

The skill create-python-x402-facilitator is designed to build a FastAPI-based service for verifying and settling x402 payments on the Algorand blockchain. This functionality inherently involves high-privilege operations and handling sensitive data.

1. Unverifiable Dependencies (MEDIUM -> HIGH due to context):

• The skill instructs pip install "x402-avm[avm,fastapi]". The x402-avm package is an external dependency and is not listed in the trusted GitHub repositories or organizations. This means its code cannot be audited as part of this analysis. Given that this library is central to handling private keys and signing blockchain transactions, the inability to verify its integrity elevates the risk significantly.

2. Credentials Unsafe (HIGH):

• The skill explicitly requires the AVM_PRIVATE_KEY to be provided as a Base64-encoded environment variable. This is a highly sensitive credential. While using environment variables is a common practice for secrets, the skill then directly decodes and uses this key for cryptographic signing operations (algosdk.Transaction.sign()). The security of this operation is entirely dependent on the x402-avm library and the skill's implementation, which cannot be fully verified.

3. Data Exfiltration (HIGH):

• The AVM_PRIVATE_KEY is handled by the skill and its unverified dependency. If the x402-avm library or the skill's logic were compromised, there is a high risk that this private key could be exfiltrated to an attacker-controlled server. Although the provided code snippets do not explicitly show exfiltration to an arbitrary server, the potential exists due to the handling of the sensitive key by unverified code. Network operations are performed to Algorand nodes (algonode.cloud), which are legitimate, but the data sent includes signed transactions derived from the private key.

4. Command Execution (HIGH):

• The core function of the skill is to sign and send blockchain transactions. This is a form of high-privilege command execution. If the x402-avm library were malicious, or if the skill's logic could be manipulated (e.g., via indirect prompt injection), it could lead to the signing and sending of arbitrary, unauthorized blockchain transactions using the provided private key.

5. Indirect Prompt Injection (INFO):

• The FastAPI endpoints (/verify, /settle) accept paymentPayload and paymentRequirements from external HTTP requests. If these input payloads can be crafted to contain malicious instructions that the x402Facilitator or AlgorandFacilitatorSigner misinterprets, it could lead to unintended behavior, such as signing an incorrect transaction or performing an unauthorized action. This is a general risk for skills processing external, untrusted input.

No other direct threats were identified:

• No explicit prompt injection patterns were found in the skill's instructions.
• No obfuscation techniques (beyond standard Base64 encoding for algosdk library requirements) were detected.
• No privilege escalation attempts (e.g., sudo, chmod 777) were found.
• No persistence mechanisms (e.g., modifying .bashrc, crontab) were detected.
• No metadata poisoning was found in the skill's description or other metadata fields.
• No time-delayed or conditional attacks were identified.