Amun contest details

• $71,250 USDC main award pot
• $3,750 USDC gas optimization award pot
• Join C4 Discord to register
• Submit findings using the C4 form
• Read our guidelines for more details
• Starts December 13, 2021 00:00 UTC
• Ends December 19, 2021 23:59 UTC

Glossary
Basket	A token that wraps multiple underlying tokens into one index Token
Rebalancing	Trading the underlying of a basket to change weights and add/remove underlying token
Root Chain	Ethereum / Goerlie
Child chain	Matic / Mumbai

Contest Scope

The focus for the contest is to try and find any logic errors or ways to drain funds from the protocol in a way that is advantageous for an attacker at the expense of users with funds invested in the protocol. Wardens should assume that governance variables are set sensibly (unless they can find a way to change the value of a governance variable, and not counting social engineering approaches for this).

Protocol overview

The amun basket protocol is an index token and the supporting contracts needed for interacting with it. The core contract is the Basket build from facets with the diamond standard. The Basket has facets adding ERC20, basket, and callManager functionality. Basket facet enables join/exiting the basket and removing/adding underlying. The CallManager facet enables manager to acct as the Basket. This allows RebalanceManager to rebalance the underlying. This contract can only be used by the owner and trades underlying via exchanges like uniswap. The SingleJoin and SingleExit are helper contracts that enable buying/selling the underlying token from a single token like WETH. The Bridge token are a pair of token enabling bridging the basket between ethereum and matic. This is done by deploying on ethereum and matic according to the Polygon PoS token standard.

Smart Contracts

All the contracts in this section are to be reviewed. Any contracts not in this list are to be ignored for this contest. A further breakdown of contracts and their dependencies can be found here

Basket

The core contract is built in separate facets (modules) with the diamond standard:

BasketFacet (342 sloc)

This module enables handling underlying token. It holds core functionality for interacting with the token.

• Managing underlying token
  • addToken/removeToken
  • joinPool/exitingPool with underlying
  • handling fees
  • calcTokensForAmount underlying ratio needed to mint quantity of token
  • calcTokensForAmountExit underlying returned when burning the basket (exit)

CallFacet (116 sloc)

Enables other contracts to act as the Basket token and makes it possible to add new logic. The contracts in callManager use this module.

• Adding and removing call manager addCaller and removeCaller
• call, callNoValue, singleCall enable creating internal contract as the basket

ERC20Facet (218 sloc)

Adds ERC20 functionalities

Call managers

Contracts that can be added to a Basket via the CallFacet, this acting as the basket

Rebalance managers

Enables rebalancing the underlying basket token by swapping underlying for new token via exchanges like uniswap. Different versions

• RebalanceManager.sol can swap on one uniswapV2 like exchange
• RebalanceManagerV2.sol can swap via multiple uniswapV2 and uniswapV3 like exchanges
• RebalanceManagerV3.sol can swap over more then one exchange in each trade

SingleJoin

Enables swapping to all underlying token required for a basket in single transaction and join the basket

• EthSingleTokenJoin.sol swapping from ETH to all underlying of a basket and joining basket

• SingleTokenJoin.sol swapping from Token to all underlying of a basket and joining basket

• EthSingleTokenJoinV2.sol swapping from ETH to all underlying via multiple exchanges of a basket and joining basket

• SingleTokenJoinV2.sol swapping from Token to all underlying via multiple exchanges of a basket and joining basket

SingleExit

Enables exiting a basket and swapping to all underlying token in a single transaction to a output token

• SingleNativeTokenExit.sol exiting and swapping underlying token of a basket to single output token
• SingleNativeTokenExitV2.sol exiting and swapping underlying token of a basket via multiple exchanges to single output token

Bridge

Representation of a token on two different chains child/root using the matic PoS bridge (HERE).

• PolygonERC20Wrapper.sol contract deployed on child side and wrapping a basket. This signals the matic bridge when to transfer from child to root chain via withdraw and withdrawTo and enables the user to call exiting function on the matic bridge and then minting MintableERC20.sol on the root chain.
• MintableERC20.sol contract deployed on root side and representing a basket on that chain. Locking the token on the bridge will signal matic to transfer underlying basket of PolygonERC20Wrapper.sol via deposit to the user on the child chain.

User interaction

User interaction start in either the deposit or withdraw handler. A user is treated differently depending on the size of the user and the type of interaction the user is doing, user interactions can be broken down in the following groups:

Setup

Go to contracts/basket and contracts/bridge.

Create .env file to use the commands (see .env.example for more info):

• PRIVATE_KEY - Credentials for the account that should be used
• INFURA_PROJECT_ID- For network that use Infura based RPC

Then run:

yarn 
yarn compile 

Deploy

Deploying Basket Token and helper contracts

Go to contracts/basket.

Deploying the factory

npx hardhat --network [NETWORK] deploy-pie-factory`

Deploying an Basket Define what underlying tokens your basket should have and get the underlying token (uniswap/mint). Then define the correct ratios in ./allocations/{TOKEN_NAME}.json to generate the Basket

npx hardhat --network [NETWORK] deploy-pie-from-factory --factory [FACTORY_ADDRESS] --allocation ./allocations/{TOKEN_NAME}.json`

Deploying an RebalanceManager (caller/manager)

npx hardhat --network [NETWORK] deploy-rebalance-manager --basket [BASKET_ADDRESS] --uniswapv2 [UNISWAP_V2_ADDRESS]

Then add the RebalanceManager as a caller

npx hardhat --network [NETWORK] add-caller-to-basket --basket [BASKET_ADDRESS] --caller [CALLER_ADDRESS]

Deploy the single swap v1

npx hardhat --network [NETWORK] deploy-single-join-exit --exchange [EXCHANGE] --token [TOKEN_ADDRESS] --weth [NATIVE_TOKEN]

Deploy the single swap v2

npx hardhat --network [NETWORK] deploy-single-join-exit-v2 --exchange [EXCHANGE] --token [TOKEN_ADDRESS] --weth [NATIVE_TOKEN]

Deploying Matic PoS Bridge Token

Go to contracts/bridge.

Deploy the child side token. This should wrap a basket token and be deployed on Matic/Mumbai.

yarn tasks deploy-child-wpeco --basket [BASKET_ADDRESS] --network [NETWORK]

Deploy the root (ethereum/goerli) side token.

yarn tasks deploy-root-wpeco --network [NETWORK]

Add mapping on Mapper Matic

Tests

A full set of unit tests are provided in folder basket and bridge. To run these do the following:

yarn test