ETH:BlockSec DeFi攻擊分析系列之二傾囊相送：Sushiswap手續費被盜-ODAILY_WET

去中心化金融(DeFi)作為區塊鏈生態當紅項目形態，其安全尤為重要。從去年至今，發生了幾十起安全事件

BlockSec作為長期關注DeFi安全的研究團隊(https://blocksecteam

_toWETH函數：

function_toWETH(addresstoken)internalreturns(uint256){//對于SUSHI，直接Sushimaker全部SUSHI轉給Barif(token==sushi){uintamount=IERC20(token)

//對于WETH，直接將全部WETH轉給WETH/SUSHI交易對，swap出相應的SUSHIif(token==weth){uintamount=IERC20(token)

//獲取token/WETH的交易對地址IUniswapV2Pairpair=IUniswapV2Pair(factory

//計算可以換出的WETH數量：amount0out，amount1Out//獲得交易對中兩種資產的數量(uintreserve0,uintreserve1,)=pair

看出什么亮點了嗎？

SushiMaker里的轉賬邏輯都是：transfer(balanceOf(this))

我們可以分兩個階段來看convert的調用過程：第一個階段：在convert函數中SushiMaker擁有的是SLP，它通過burnbalanceOf(this)實現將全部SLP換成兩個底層代幣第二個階段：SushiMaker獲得了burn來的底層代幣，再拿burn得到的token去不同的交易池換wETH

你發現哪里有問題了嗎？我們來看第二階段的代碼_toWETH：注意兌換的邏輯為：

uintamount=IERC20(token)

,"profit":"0

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Art Blocks NFT Fidenza#562以117ETH價格成交:金色財經報道，Etherscan數據顯示，Art Blocks NFT Fidenza#562以117ETH價格成交。[2022/10/9 12:50:42]

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,{"YFI/WETH":{"0x1b0eb70bc4d2407745df416acf6e2c312d25ee63c7e8e1291545d66e23fbf704":"PreAttack","0x8f6caabd4ecfad30793db76f60a7e28832a18e2bcf006c0ee3652063c7386778":"Convert","0xe6d28052b55ab520a211daebbc67ee3aece6ae356044e9352fc82910214a038a":"Swap"},"profit":"-0

,{"AXS/WETH":{"0x375f5befeb1af976ebb09cf5539b3a3b9746b87153cfa96ba862deb8828970f1":"PreAttack","0xed8508a18c347c3829024f7acb94056a78cc63152e2246ebd42b59cd86d0c8f9":"Convert","0xd08eb264e39cd5dca8edb3684dfd36afb905aea9c47a43110b6c5c45bdb2f7d1":"Swap"},"profit":"1

Fireblocks宣布支持TRX及波場鏈上全部TRC20代幣:據官方消息，數字資產和加密貨幣基礎設施平臺Fireblocks宣布，旗下專注機構業務的數字資產平臺正式新增對TRX和波場鏈上所有TRC20代幣的支持。Fireblocks 網絡上1200 多位流動性合作方、交易機構及交易方目前可通過波場鏈安全收發或托管TRX及BTT、JST、NFT等其它TRC20代幣。

Fireblocks 是一個企業級平臺，為轉移、存儲、發行數字資產提供可靠的基礎設施，現已支持超過 1100 種代幣和 35 個協議。Fireblocks用戶已利用該平臺積累托管資產 450 億美元，為各大機構超過 2.5 萬億美元的數字資產轉賬提供技術支持。

波場TRON致力于打造下一代全球互聯網及金融基礎設施，交易手續費極低、可擴展性高，且擁有業內規模最大、最活躍的社區。目前，波場公鏈用戶總數超過9400萬，交易筆數超32億，總鎖倉量（TVL）超100億美元。[2022/5/24 3:37:30]

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,{"USDC/WETH":"Failed"},{"COVER/WETH":"Failed"},{"YAX/WETH":{"0x063bc5df97c0ec87d6c309b54fbc4e3ed13b22f5a115fb1170015e4e9d23cd3d":"PreAttack","0x9537551d0db7ed6ae372c050c73cae1272f4d7e7847ea908d6e4d440809a871f":"Convert","0x9f6bdf1c9065f5f5e5c71f32058093b7ac06e140c3a33db2f21cc8a5ff8a5d21":"SwapExactETHforTokens","0x9281c35277ea6594924600d70b73077a4307973c540edb5b4ed534c7e25f2423":"Approve","0xe2f682d8b4801061d504025f11b3032648a3b94019396f7b12749b162f8404cf":"RemoteLiquidityETH","0xf6ea6c9eb92ca9aed70e8b4b03a6e5565a3a13df71a0aa527fa556077de553bc":"Approve","0xbf19c9a6a4d879467519299100b4f56c4e86369382ba87d90bebf6c1b1893c14":"SwapExactTokensForETH"},"profit":"1

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掌柜調查署 | bloXmove CEO：移動出行運營模式將會是去中心化的，供應商之間的交互是通過分布式記賬完成的:在今日舉行的《掌柜調查署 | 呼吁出行巨頭停止聚合開始協作》直播中，針對“移動出行涉及到許多不同的運營主體，在去中心化的模式下，bloXmove將如何協調不同運營主體間的協作與利益？”的問題，德國柏林bloXmove CEO Sophia表示，從更傳統的移動出行看，運營模式也將會是去中心化的，這意味著生態系統或技術不屬于任何一個個體，它是一個基于合作合約的集體，合作伙伴在進入bloXmove的生態系統之初就定義了這個合約。bloXmove團隊正在促進我們的生態系統合作伙伴（也就是客戶）的商業決策，在操作過程中，供應商之間的交互是通過分布式記賬和去中心化標識完成的，各方都可以訪問交易所需的相關信息——這就是區塊鏈獨特的魅力。[2021/8/31 22:47:46]

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Block.one獲得基于區塊鏈招標方法專利 以激發社交媒體平臺上反饋:根據美國專利商標局4月28日發布的文件，Block.one獲得了一項基于區塊鏈的招標方法的專利。該專利于去年5月首次提出，旨在解決目前缺乏激勵方法的問題，社交媒體用戶無法通過投票，贊美，和評論。Block.one設計了一種新的出價方法，以向帖子原始作者以外的用戶授予展示機會。具體來說，系統將首先通過區塊鏈驗證帖子的真實性，以確保內容是作者的原創作品。然后，希望與該帖子相關聯的用戶可以使用社交媒體平臺分發的令牌對其進行出價。出價最高的人的個人資料將顯示在該帖子的顯眼位置。（The Block）[2020/5/2]

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,{"RSR/WETH":{"0xa69b5290fe5dd5580e0c738baa47000cf51ed77cc06b8b54a244c7509f8002ad":"PreAttack","0x87a639847c58b6704f28407be39e3ec64b01f005b47753b1a99faf776ea11780":"Convert","0xa458915881d79debafe5f465843931e572321d35bc98ec25db9ecb9f6a3ea6fd":"Swap"},"profit":"0

,{"CORE/WETH":{"0xa01fd6fcfee90a7a2b0a180e7271b9429e9f23cf502ba7966932e5012c1bc9b7":"PreAttack","0x05af95d603cba12d9ca14ce307a973c8875cdcb2e70b07b295440cd2940ea953":"Convert","0x9bb8b7ca5b41c55a8efcdcd49fdec16747ccee0bf33df8e8f4d62eb116142b21":"Swap"},"profit":"0

,{"zLOT/WETH":{"0x0bb5d792a1d1ea598e45997d5dedb4fcf6acafab47afdb45892417cd128cf37f":"PreAttack","0x2550eb33adbe7cfb68cce685363ad2cab90860e5e8a8ed87de1f0a6321e24cf8":"Convert","0x514bd13f68c8afc1f86ea3e74ca5f51724c2736fa327144b7b6aaf7228bd9124":"Swap"},"profit":"0

動態 | 以太坊The DAO項目開發公司被Blockchains.com收購:6月4日訊，據CoinDesk消息，區塊鏈孵化與投資機構 Blockchains.com 宣布收購德國區塊鏈公司slock.it。slock.it 成立于 2015 年，曾開發以太坊去中心化組織項目The DAO。slock.it 計劃未來數月發布一系列開源工具，供以太坊開發者社區使用。此外，slock.it 兩位創始人 Christoph 與 Simon Jentzsch 兩兄弟將分別擔任 Blockchains 的技術副總和區塊鏈開發主管。[2019/6/4]

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,{"YFI/WETH":{"0xf28c246bf1ce25da1811c7c0eb6fefb8587fa2cdafc84cec4e709600429e6e3f":"PreAttack","0xc75a8ca881d4da75774f51006651c9946311d40145ce69d07aee3a85627153d6":"Convert","0x332c7eff23c9022fe6578550a079034cd3356d9f66507d2ec38462169a4b282c":"Swap"},"profit":"0

,{"UBXT/WETH":{"0x635c79a8dca89a3aa95f545e2243a735906c4ff221cfbc160396c150d58ea036":"PreAttack","0x3ffcfc9985622ad7cf0fdc2eb582ad7ce8bf9e9295fd7a4de44354fdd71a688a":"Convert","0x7c6af5ca27ceb04aad514ddcaee8afc6dd4eb79d0816e24b007e7db205e93ce3":"Swap"},"profit":"1

,{"0xMaki":"Iseeu."},{"WBTC/WETH":{"0xa195c9c23a56ca5fa747677c04a2d5a8c513bdfd141e45c20a8c4e091ca73883":"PreAttack","0x136b1d2bf6c51a6ed1fc3f1da7a2783e3835fa78c9149c1c6d2b21e9aad8b05b":"Convert","0x43cde98b0be5932b8dbf709eebd0cbb4738599c9a4f0795ddb52d7d31f293cf4":"Swap"},"profit":"2

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,{"LINK/WETH":{"0x95eea1cedccffc405d0cb9743360712b69a295a66fe0649b5ab1b067869f05fa":"PreAttack","0xf259718ee2f81b543bbfbe2f236cd4235651f8365ec8944741a3c7f3242f06b9":"Convert","0x525929006fc3f089d67b6596f53c5ebe6b82de1f8d3cdeb397f1f55ff4937c47":"Swap"},"profit":"0

后續攻擊者又嘗試攻擊Sushiswap的其他相關仿盤項目，如LuaSwap：

https://etherscan

function_toETH(addresstoken){..

New：0x280ac711bb99dE7C73FB70fb6DE29846D5e4207Ffunctionconvert(addresstoken0,addresstoken1)public{//Atleastwetrytomakefront-runninghardertodo

function_toETH(addresstoken,uintamountIn){...}

可以看到區別在于：代碼第26行_toWETH限制了amount，這樣修改以后就不會將SushiMaker中存的全部SLP都去池中換成wETH，而只是換取burn出的一部分

但是這樣問題就解決了嗎？其實還沒有，時隔兩個月，同樣的地方，Sushiswap又中槍了見：amenda：SushiSwap攻擊事件(2021年1月27號)分析(https://zhuanlan.zhihu.com/p/372058217)

0x3.參考

以小博大，簡述SushiSwap攻擊事件始末：https://www.chainnews.com/zh-hant/articles/726256718885.htm

Astokenpricerisesandreputationmends,Sushiswapfoilsmidnightexploit:https://cointelegraph.com/news/as-token-price-rises-and-reputation-mends-sushiswap-foils-midnight-exploit

AnevolutionofUniswapwithSUSHItokenomics：https://sushichef.medium.com/the-sushiswap-project-dd6eb80c6ba2

一文看懂Uniswap和Sushiswap：https://zhuanlan.zhihu.com/p/226085593

sokdecentralizedexchanges(dex)withautomatedmarketmaker(amm)protocols:https://arxiv.org/abs/2103.12732

AttackingtheDeFiEcosystemwithFlashLoansforFunandProfit:https://arxiv.org/abs/2003.03810

https://www.blocksecteam.com/

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