Astaria contest - pwnforce's results

Lines of code

https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/AstariaRouter.sol#L490 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/AstariaRouter.sol#L795 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/Vault.sol#L66 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/Vault.sol#L72 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/PublicVault.sol#L384 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/VaultImplementation.sol#L394 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/VaultImplementation.sol#L406 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/ClearingHouse.sol#L143 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/ClearingHouse.sol#L161 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/TransferProxy.sol#L34 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/WithdrawProxy.sol#L269 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/WithdrawProxy.sol#L281 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/WithdrawProxy.sol#L298

Vulnerability details

Impact

There is a subtle difference between the implementation of solmate’s SafeTransferLib and OZ’s SafeERC20: OZ’s SafeERC20 checks if the token is a contract or not, solmate’s SafeTransferLib does not. See: https://github.com/Rari-Capital/solmate/blob/main/src/utils/SafeTransferLib.sol#L9 Note that none of the functions in this library check that a token has code at all! That responsibility is delegated to the caller. As a result, when the token’s address has no code, the transaction will just succeed with no error. This attack vector was made well-known by the qBridge hack back in Jan 2022.

In AstariaRouter, Vault, PublicVault, VaultImplementation, ClearingHouse, TransferProxy, and WithdrawProxy, the safetransfer and safetransferfrom don't check the existence of code at the token address. This is a known issue while using solmate’s libraries.

Hence this can lead to miscalculation of funds and also loss of funds , because if safetransfer() and safetransferfrom() are called on a token address that doesn’t have contract in it, it will always return success. Due to this protocol will think that funds has been transferred and successful , and records will be accordingly calculated, but in reality funds were never transferred. So this will lead to miscalculation and loss of funds.

Attack scenario (example):

It’s becoming popular for protocols to deploy their token across multiple networks and when they do so, a common practice is to deploy the token contract from the same deployer address and with the same nonce so that the token address can be the same for all the networks. A sophisticated attacker can exploit it by taking advantage of that and setting traps on multiple potential tokens to steal from the borrowers. For example: 1INCH is using the same token address for both Ethereum and BSC; Gelato's $GEL token is using the same token address for Ethereum, Fantom and Polygon.

• ProjectA has TokenA on another network;
• ProjectB has TokenB on another network;
• ProjectC has TokenC on another network;
• A malicious strategist (Bob) can create new PublicVaults with amounts of 10000E18 for TokenA, TokenB, and TokenC.
• A few months later, ProjectB lunched TokenB on the local network at the same address;
• Alice as a liquidator deposited 11000e18 TokenB into the vault;
• The attacker (Bob) can withdraw to receive most of Alice added TokenB.

Proof of Concept

https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/AstariaRouter.sol#L490 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/AstariaRouter.sol#L795 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/Vault.sol#L66 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/Vault.sol#L72 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/PublicVault.sol#L384 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/VaultImplementation.sol#L394 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/VaultImplementation.sol#L406 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/ClearingHouse.sol#L143 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/ClearingHouse.sol#L161 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/TransferProxy.sol#L34 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/WithdrawProxy.sol#L269 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/WithdrawProxy.sol#L281 https://github.com/code-423n4/2023-01-astaria/blob/1bfc58b42109b839528ab1c21dc9803d663df898/src/WithdrawProxy.sol#L298

Tools Used

Manual Audit

Recommended Mitigation Steps

This issue won’t exist if OpenZeppelin’s SafeERC20 is used instead.