Which programming languages does this scanner support?

This skill specifically targets the FunC language (.fc and .func files), which is the primary language used for developing smart contracts on The Open Network (TON).

Why is integer-as-boolean usage a security risk in FunC?

In FunC, 'true' is represented by -1 (all bits set). Using 1 for true can lead to logic errors when using bitwise NOT (~) operations, potentially bypassing critical security checks.

What are the three specific vulnerabilities it checks for?

It focuses on three critical TON-specific patterns: Integer-as-boolean misuse, missing sender validation in Jetton handlers (Fake Jettons), and improper gas handling for forwarded TON messages.

Can this tool prevent contract balance drainage?

Yes, it checks if forward_ton_amount is properly validated against the incoming msg_value to ensure the contract doesn't pay for user-requested transfers using its own balance.

How does it detect 'Fake Jetton' vulnerabilities?

The scanner analyzes transfer_notification handlers to ensure the contract verifies that the sender is the legitimate, stored Jetton wallet address rather than an arbitrary attacker contract.

TON Smart Contract Security Scanner

The TON Vulnerability Scanner is a specialized security auditing tool built for developers and researchers working on The Open Network (TON). It systematically scans FunC contracts for three high-impact, platform-specific vulnerability patterns: improper boolean representation (using 1 instead of -1), missing sender validation in Jetton transfer notifications, and insufficient gas reservations for forwarded TON. By automating the detection of these nuanced architectural risks, the skill helps prevent common exploits such as fake token deposits and contract balance drainage, ensuring safer dApp deployments on the TON ecosystem.

Key Features

01Detects improper integer-as-boolean logic specific to the FunC compiler.

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03Offers actionable code fixes and unit test templates for identified vulnerabilities.

04Identifies missing sender checks in Jetton transfer notification handlers to prevent fake deposits.

05Provides automated grep-based search patterns for efficient codebase auditing.

06Flags potential contract balance drainage caused by unvalidated forward TON amounts.

Use Cases

01Reviewing gas economics and message forwarding logic in complex TON decentralized applications.

02Validating Jetton token implementations to ensure robust sender verification logic.

03Performing security audits on FunC smart contracts before mainnet deployment.

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add trailofbits/skills ton-vulnerability-scanner

For use in Claude.ai and ChatGPT

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