Tornado Cash

Tornado Cash is a fully decentralized non-custodial protocol allowing private transactions in the crypto-space. Tornado Cash improves transaction privacy by breaking the on-chain link between source and destination addresses. It uses a smart contract that accepts ETH & other token deposits from one address and enables their withdrawal from a different address.

As a non-custodial protocol, users keep custody of their cryptocurrencies while operating Tornado Cash. At each deposit, users are provided with the private key enabling the access to the deposited funds, which gives users complete control over their assets.

For more information about Tornado Cash, please visit https://tornado.cash/.
This bug bounty program is focused on their smart contracts and is focused on preventing:

• Thefts or freezing of funds in anonymity pool
• Thefts or freezing of unclaimed yield (TORN anonymity mining)
• Theft of governance funds (Main on-chain Tornado DAO treasury only)
• On chain governance activity disruption

Rewards are distributed according to the impact of the vulnerability based on the Immunefi Vulnerability Severity Classification System. This is a simplified 5-level scale, with separate scales for websites/apps and smart contracts/blockchains, encompassing everything from consequence of exploitation to privilege required to likelihood of a successful exploit.

All smart contract bug reports must come with a PoC in order to be considered for a reward.

This bug bounty program has fixed rewards in TORN. The USD amounts reflected are only estimates. For an up-to-date price of the token, please visit https://tornado.cash/.

Critical smart contract vulnerabilities are further capped at 10% of economic damage, primarily taking into account the funds at risk. However, there is a minimum reward of 2 000 TORN. Additionally, the maximum reward is capped at 32 500 TORN, even if 10% of the damage in USD equivalent is greater than the USD equivalent of 32 500 TORN.

Payouts are handled by the Tornado Cash team directly and are denominated in TORN. Payouts are done in TORN.

All smart contracts of Tornado Cash can be found at https://github.com/tornadocash. However, only those in the Assets in Scope table are considered as in-scope of the bug bounty program.

Impacts in Scope

Only the following impacts are accepted within this bug bounty program. All other impacts are not considered as in-scope, even if they affect something in the assets in scope table.

Smart Contracts/Blockchain

• Thefts or freezing of funds in anonymity pool
• Thefts or freezing of unclaimed yield (TORN anonymity mining)
• Theft of governance funds (Main on-chain Tornado DAO treasury only)
• On chain governance activity disruption

We are especially interested in receiving and rewarding vulnerabilities of the following types:

Smart Contracts and Blockchain

• Re-entrancy
• Logic errors
  • including user authentication errors
• Solidity/EVM details not considered
  • including integer over-/under-flow
  • including rounding errors
  • including unhandled exceptions
• Trusting trust/dependency vulnerabilities
  • including composability vulnerabilities
• Oracle failure/manipulation
• Novel governance attacks
• Economic/financial attacks
  • including flash loan attacks
• Congestion and scalability
  • including running out of gas
  • including block stuffing
  • including susceptibility to frontrunning
• Consensus failures
• Cryptography problems
  • Signature malleability
  • Susceptibility to replay attacks
  • Weak randomness
  • Weak encryption
• Susceptibility to block timestamp manipulation
• Missing access controls / unprotected internal or debugging interfaces

The following vulnerabilities are excluded from the rewards for this bug bounty program:

• Attacks that the reporter has already exploited themselves, leading to damage
• Attacks requiring access to leaked keys/credentials
• Attacks requiring access to privileged addresses (governance, strategist)

Smart Contracts and Blockchain

• Incorrect data supplied by third party oracles
  • Not to exclude oracle manipulation/flash loan attacks
• Basic economic governance attacks (e.g. 51% attack)
• Severe break of privacy due to issues with the SNARK logic/code
• Lack of liquidity
• Best practice critiques
• Sybil attacks
• Centralization risks

The following activities are prohibited by this bug bounty program:

• Any testing with mainnet or public testnet contracts; all testing should be done on private testnets
• Any testing with pricing oracles or third party smart contracts
• Attempting phishing or other social engineering attacks against our employees and/or customers
• Any testing with third party systems and applications (e.g. browser extensions) as well as websites (e.g. SSO providers, advertising networks)
• Any denial of service attacks
• Automated testing of services that generates significant amounts of traffic
• Public disclosure of an unpatched vulnerability in an embargoed bounty