DeFi周选丨bZx事件反思:闪电贷(Flash Loan)的横空出世意味着什么?_LibraNews_服务于区块链创新者

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本期内容:

  1. 一周DeFi数据:情人节Defi锁仓总值达到17.5亿美元,ETH锁仓量继续下滑
  2. 反思bZx攻击事件,谁该为损失负责?
  3. 神奇的闪电贷(Flash Loan)发展得如何?
  4. 关于bZx事件的金句评论
  5. 一周DeFi项目进展
  6. 总结

根据dapptotal统计的Defi数据显示,在情人节当天,Defi生态锁仓总值创下了17.5亿美元的峰值,而随着ETH和EOS价格的回调,当前Defi生态的锁仓资金已回落到15.3亿美元,但较上周仍增长3.53%,其中Maker锁仓6.233亿美元,占比40.04%,EOSREX锁仓2.948亿美元,占比18.94%。

另外,数据显示,当前Defi生态的ETH锁仓量约为391万ETH,同比上周减少约10万ETH,这进一步印证了我们上一期中的猜测。DeFi周选丨bZx事件反思:闪电贷(Flash Loan)的横空出世意味着什么?_LibraNews_服务于区块链创新者

而本周Defi生态当中,最引入关注的要属bZx攻击事件,2天前,DeFi协议bZx遭受了严重而复杂的攻击,攻击者同时跨多个协议(包括Compound、dYdX、Uniswap等)完成了一笔闪电贷(Flash Loan)杠杆套利交易,并成功获取了一笔ETH利润,而剩余的51.34 WBTC利润则遭到了bZx项目方的锁定。

DeFi周选丨bZx事件反思:闪电贷(Flash Loan)的横空出世意味着什么?_LibraNews_服务于区块链创新者

 (图片来自:tuchong.com)

 

反思bZx攻击事件,谁该为损失负责?

 

这笔复杂的交易,有人称之为攻击,也有人认为它只是一个成功的交易策略,因此应该获得奖励,另外,bZx官方动用管理密钥锁定资金的行为,也引发了针对DeFi本身的争论。

首先,我们先通过一个可视化图来看这笔神奇的交易:

DeFi周选丨bZx事件反思:闪电贷(Flash Loan)的横空出世意味着什么?_LibraNews_服务于区块链创新者

(图片来自:Julien Bouteloup)

其大致步骤是:

  1. 0成本从dYdX借得10000 ETH;
  2. 将5500 ETH存到Compound,然后借得112 WBTC;
  3. 将1300 ETH发送到Fulcrum/bZX做空WBTC,Fulcrum从bZx贷款人处额外借款4337.6(5637.6-1300) ETH,并在Uniswap(通过Kyber)购买51.34 WBTC,导致WBTC价格暂时大幅上涨;
  4. 攻击者利用这个峰值在Uniswap上售出112 WBTC,并获得6871.41 ETH作为回报;
  5. 最后一步是偿还dYdX的10,000 ETH贷款,此时攻击者剩余的3200 ETH以及6871.41 ETH就可以拿来归还10,000 ETH贷款,其还能够盈利71.41ETH。

惊人的是,这些复杂的步骤是在同一笔交易内完成的,无论是策略还是执行,都让人惊叹。

这是这个交易的过程记录:http://ethtx.info/0xb5c8bd9430b6cc87a0e2fe110ece6bf527fa4f170a4bc8cd032f768fc5219838

在这起事件发生后,dYdX没有损失也没有收益,Compound池获得一笔收益,策略执行者(攻击者)获得一小笔ETH收益,bZx的iETH池遭遇惨重,为了减少损失,bZx动用管理密钥锁定了攻击者的51.34 WBTC。

而这次攻击在展示了闪电贷(Flash Loan)神奇魅力的同时,也暴露出来了几个问题:

  1. bZx动用管理密钥冻结攻击者的51.34 WBTC,这个操作是极具争议性的,一方面不这么做,项目方的损失会非常惨重,但这又暴露出当前它是中心化的本质,而当前的DeFi项目都存在管理密钥,无疑,bZx的操作对DeFi生态而言会是个污点,而用DAO的形式来负责管理密钥的讨论,也会越来越多;
  2. 流动性差的池会被利用;
  3. 早期阶段的DeFi,会随着越来越多新的产品和功能(例如这次的闪电贷)而暴露出更多新的问题;

截至目前,bZx已宣布会采用Chainlink的喂价解决方案。

 

神奇的闪电贷(Flash Loan)发展得如何?

 

上面,我们谈到了神奇的闪电贷(Flash Loan),正是这个新的功能,使得bZx攻击事件成为了可能,那它是哪家的产品,以及现在发展得如何了呢?

这就要从一个月前说起了,当时,Aave协议刚在以太坊主网正式上线,至今,该协议的市场规模已超过了1500万美元,短短的时间内,Aave协议就超过了市场上很多存在已久的DeFi产品,而其凭借的就是闪电贷(Flash Loan),这是一种新的DeFi原语,它允许用户在单笔交易中进行未抵押贷款,那它现在的情况是怎么样的呢?

来自Emilio Frangella的一篇文章对其进行了简单介绍:

原文链接:https://medium.com/aave/flash-loans-one-month-in-73bde954a239

如下图所示:

DeFi周选丨bZx事件反思:闪电贷(Flash Loan)的横空出世意味着什么?_LibraNews_服务于区块链创新者

闪电贷(Flash Loan)目前最常见的用例就是套利,其次是清算,最后则是抵押品交换,而这是有原因的:

  1. 与清算相比,DEX套利事件通常更频繁;
  2. 抵押品交换是最近才建立起来的,而且它仍然是非常实验性的;

随着开发人员对闪电贷(Flash Loan)功能的试用,每天都会出现新的用例和想法。开发人员特别渴望构建跨DeFi协议工具来测试以太坊可组合性的边界。最近的一个例子是Maker-Vault Swap,它需要Aave、UniSwap和Maker来共同完成。

费用和收入分别是多少?

当前,闪电贷(Flash Loan)会有0.35%的费用,其中70%会被分配给存款人,剩下30%使用相同的2/8费用发放模型进行分割。另外,在以太坊区块链上进行交易还有额外的费用,这些费用取决于网络状态和交易复杂度。

那进行闪电贷(Flash Loan)交易,相关方的收入是多少呢?

在下表中,我们分析了存款人、协议和闪电贷(Flash Loan)执行人获得的收益情况:

DeFi周选丨bZx事件反思:闪电贷(Flash Loan)的横空出世意味着什么?_LibraNews_服务于区块链创新者

上面的图表清楚地显示了套利用例中收益的不均匀分布情况。

事实上,大多数时候,协议和存款人的收入都超过了实际的闪电贷(Flash Loan)用户。由于我们还需要从闪电贷所带来的套利机会中减去用户所承受的交易成本,执行人只能通过大金额的闪电贷机会中获利。而在大部分交易中,套利者都蒙受了损失。

原因可能是:

  1. 套利通常涉及相对较少的资金,利润通常很小。套利的利润很少超过0.5%,而0.35%的手续费,使得套利者的利润就所剩无几了;
  2. 套利通常涉及gas竞价,人们在比赛中使用逐渐上涨的gas价格来获取价差,这导致了高昂的交易成本;

为什么不是零手续费?

有人提问,为什么不取消手续费,这样可以刺激闪电贷(Flash Loan)的发展,这实际是权衡的结果,这些费用中的大部分都流向了流动性提供者,这首先使闪电贷成为可能。

另外,虽然闪电贷(Flash Loan)利用了以太坊区块链执行原子交易的能力。这意味着,如果由于执行人没有返还足够的资金而导致闪电贷(Flash Loan)失败,那么交易就会被撤销,这看起来可以把风险降到最低,但实际仍存在一定程度的风险,这涉及到智能合约和底层(区块链本身)。

闪电贷(Flash Loan)利用一个特定的条件来运作,强制资金在执行结束时返还。在合约的字节码中,或者在EVM的更深层,仍然有可能会存在漏洞,使得攻击者能够绕过这种情况。即使这种可能性是极其微小的,我们也需要重视起来。

闪电贷(Flash Loan)的费用有利于生态系统,这种收入来源使闪电贷(Flash Loan)与其他类似产品相比具有竞争优势。这会吸引更多的流动性,进而允许更大额的闪电贷(Flash Loan),从而为存储用户带来更多的收益,等等。

接下来的计划?

随着协议越来越去中心化,闪电贷(Flash Loan)费用将成为调整整体token经济的投票参数之一。由于Aave团队仍然在内部控制着管理密钥,因此就需要启用一个临时DAO,并对更新进行投票。

根据上个月的社区反馈和讨论,很明显,费用需要适当调整。因此,Aave将发布治理投票,将闪电贷(Flash Loan)费用降低至0.09%。

 

关于bZx事件的金句评论

 

  1. “这就是为什么我不相信DeFi,大多数DeFi可以被一个中央实体关闭,所以它只是一个去中心化剧场。然而,除非我们增加更多的中心化,否则对于黑客攻击或漏洞的利用,人们就无能无力。那么,这要比我们现在的情况要好多少呢?” —— 莱特币创始人Charlie Lee
  2. “DeFi管理密钥允许你暂停或冻结合约,这太糟糕了?哦,不,它与中心化交易所的不同之处在于,管理者密钥无法让你没收单个用户的余额。” —— Eric Wall
  3. “不受欢迎的意见,35万美元的套利剥削只是DeFi的开始,未来几年我们还会看到更糟糕的情况。” —— Economic Bandwidth首席执行官Lucas
  4. “闪电贷基本上就是无需抵押品的贷款,bZx事件并不是一次黑客事件,而是一个如此聪明的策略,执行者应该得到这样的奖励。由于这一事件,DeFi智能合约将变得更加强大。” —— Fiona Kobayashi
  5. “DeFi不仅仅有智能合约风险,通常还存在流动性和财务攻击风险,可能会影响某些协议的用户。在这个刚刚起步的阶段,最好的应对风险的方法,就是假设你的资金可能会丢失。对不起,但事实就是这样。” —— DCinvestor.eth

 

一周DeFi项目进展

 

    1.  Chainlink将为DeFi产品推出元预言机 ;
    2. 火币全球站宣布正式上线锚定比特币的DeFI项目HBTC ;
    3. DeFI借贷协议bZx遭遇攻击,损失或达数十万美元 ;
    4. bZx宣布接入Chainlink ;

 

总结

 

闪电贷(Flash Loan)的发展,展现出了DeFi更多的可能,但同时也引入了新的问题,bZx事件的发生固然是不幸的,但它却很好地提醒了整个DeFi生态,而批评的声音,也将是相关项目前进的动力。

免责声明:本文转载自互联网,经授权后发布,版权归原作者所有,转载请联系原作者并获许可。文章观点仅代表作者本人,不代表Libra资讯立场。若内容涉及投资建议,仅供参考勿作为投资依据。投资有风险,入市需谨慎。

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