FOR.MEME遭到黑客袭击，损失约为15,000美元

Four.meme是由Binance Academy孵育的Memecoin Launchpad，类似于Pump.Fun。我们检测到该平台上的Memecoin滑雪板（https://four.meme/token/0x4abfd9a204444bd81a276c075ef89412c9fd2f64）在该平台上遭到黑客攻击。

Four.meme, a memecoin launchpad incubated by Binance Academy, is attacked by hackers

Fout.meme是由Binance Academy孵化的Memecoin Launchpad，受到黑客攻击

We noticed that memecoin snowboard ( https://four.meme/token/0x4abfd9a204344bd81a276c075ef89412c9fd2f64 ) on the platform was attacked by hackers. The loss was about 15,000 USD. The attack transaction was: https://bscscan.com/tx/0x2902f93a0e0e32893b6d5c907ee7bb5dabc459093efa6dbc6e6ba49f85c27f61

我们注意到该平台上的Memecoin滑雪板（https://four.meme/token/0x4abfd9a204444bd81a276c075ef89412c9fd2f64）在该平台上遭到黑客攻击。损失约为15,000美元。攻击交易是：https：//bscscan.com/tx/0x2902f93a0e0e32893b6d5c907ee7ee7bb5dabc4593093efa6dbc6dbc6e6ba49f855c27f61

Attack and incident analysis

攻击和事件分析

Principle of Four.meme

四分之一的原则

four.meme is a memecoin launchpad on bnb smartchain, similar to pump.fun. Three main stages of similar launchpad platforms:

Four.meme是BNB SmartChain上的Memecoin Launchpad，类似于Pump.Fun。类似启动板平台的三个主要阶段：

• Phase 1: Users create memecoins on the platform by customizing their names, logos, descriptions, social accounts (optional), etc.

•阶段1：用户通过自定义其姓名，徽标，描述，社交帐户（可选）等来创建模因。

• Phase 2: Other users can buy and sell the memecoin on the platform

•第2阶段：其他用户可以在平台上买卖Memecoin

• Phase 3: When the market value of the memecoin reaches a certain threshold (24 BNB), it will be migrated to DEX (PancakeSwap)

•第3阶段：当Memecoin的市场价值达到一定阈值（24 BNB）时，它将迁移到DEX（Pancakeswap）

Below, we take a closer look at the specific technical details of each stage.

下面，我们仔细研究了每个阶段的具体技术细节。

Phase 1

阶段1

On the launchpad platform, users fill in the specific information of the memecoin they want to create through the interface.

在启动板平台上，用户填写了他们想通过界面创建的模因的特定信息。

After filling in the form, pay the handling fee to complete the creation of the memecoin on-chain contract. Of course, this contract is created by the official contract of launchpad, so the owner of the created ERC-20 Token is also the official contract of launchpad. Let's take a look at an example of memecoin creation by four.meme:

填写表格后，支付处理费，以完成链接链合同的创建。当然，该合同是由LaunchPad的正式合同构成的，因此创建的ERC-20代币的所有者也是Launchpad的正式合同。让我们以四分之一的方式来看看Memecoin创建的示例。

First, the user pays the handling fee, the launchpad official contract completes the deployment of the memecoin ERC-20 Token contract, and mints 1,000,000,000 initial funds (the total virtual pool of the memecoin is expected to be 30 BNB).

首先，用户支付处理费，启动板官方合同完成了Memecoin ERC-20代币合同的部署，而MINT则为1,000,000,000个初始资金（预计Memecoin的Virtual Pool池预计为30 BNB）。

Then, we see that the owner of the created Token is also the smart contract of the launchpad official website.

然后，我们看到创建令牌的所有者也是Launchpad官方网站的智能合同。

This means that although memecoin is created by the user on launchpad, the owner of the ERC-20 contract on the chain is not the user. This can prevent malicious behaviors such as users minting on their own. Once the memecoin smart contract is deployed on the chain, it enters the second stage, and all users on the platform can buy and sell.

这意味着，尽管用户在启动板上创建了Memecoin，但链条上的ERC-20合同的所有者不是用户。这可以防止恶意行为（例如用户自己铸造）。一旦将Memecoin智能合约部署在链条上，它将进入第二阶段，平台上的所有用户都可以买卖。

Phase 2

第2阶段

Other users on the platform can buy and sell through the platform, but the tokens after buying and selling cannot be transferred to other users through transfer. We can take a look at the source code of the ERC-20 Token on the chain.

平台上的其他用户可以通过平台买卖，但是买卖后的代币不能通过转移转移给其他用户。我们可以查看链条上的ERC-20令牌的源代码。

In _beforeTokenTransfer, the transfer is restricted by the parameter _mode

在_beforetokentransfer中，传输受参数_mode的限制

At this point, we can see that the _mode corresponding to the Token in phase 2 is 1, which is MODE_TRANSFER_RESTRICTED, restricting third-party transfers.

在这一点上，我们可以看到，与令牌相对应的_mode是1阶段1，它是mode_transfer_renter，限制了第三方转移。

This is to prevent the influence of OTC on the price. When buying and selling, the four.meme contract sets _mode to 2 first and then uses transfer to transfer to the user. After the transfer is completed, _mode is set to 1 to restrict other users from transferring. To complete the transfer of memecoin after purchase.

这是为了防止OTC对价格的影响。购买和销售时，最终合同将_mode首先设置为2，然后使用转移将其转移给用户。传输完成后，将_mode设置为1，以限​​制其他用户传输。购买后完成Memecoin的转移。

Phase 3

阶段3

When the market value of the memecoin reaches 24 BNB, the Bonding Curve Process reaches 100%. Launchpad will migrate the remaining 20% of memecoin and 24 BNB to DEX PancakeSwap. At this point, Phase 3 is officially completed. The following transaction is the transaction in which Launchpad migrated the memecoin to PancakeSwap.

当Memecoin的市场价值达到24 BNB时，粘结曲线过程将达到100％。 LaunchPad将将其余20％的Memecoin和24 BNB迁移到Dex Pancakeswap。此时，第3阶段已正式完成。以下交易是发射台将Memecoin迁移到PancakesWap的交易。

We can see that first, launchpad officials set the _mode of memecoin to 0, that is, MODE_NORMAL, allowing users to conduct over-the-counter transactions. Then, launchpad officials created a trading pair of memecoin and WBNB, and finally added 23.5BNB (0.5 BNB is the fee) and 200 million memecoin liquidity to the trading pair. The price of adding liquidity is sqrtPriceX96 = 27169599998237907265358521. Because the calculation formula of sqrtPriceX96 is as follows:

我们可以看到，首先，LaunchPad官员将Memecoin的模具设置为0，即Mode_normal，允许用户进行非处方交易。然后，LaunchPad官员创建了一对Memecoin和WBNB的交易，最终增加了235亿枚（费用为0.5亿美元），并在交易对中增加了235亿美元的销售。增加流动性的价格为SQRTPRICEX96 = 2716959999998237907265358521。因为SQRTPRICEX96的计算公式如下：

Therefore, the price of this memecoin when adding liquidity is 0.0000001175 WBNB, which can also be obtained by dividing 2

因此，添加流动性时该模因的价格为0.0000001175 WBNB，也可以通过除以2来获得