FOR.MEME遭到黑客襲擊，損失約為15,000美元

Four.meme是由Binance Academy孵育的Memecoin Launchpad，類似於Pump.Fun。我們檢測到該平台上的Memecoin滑雪板（https://four.meme/token/0x4abfd9a204444bd81a276c075ef89412c9fd2f64）在該平台上遭到黑客攻擊。

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

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

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

我們注意到該平台上的Memecoin滑雪板（https://four.meme/token/0x4abfd9a204444bd81a276c075ef89412c9fd2f64）在該平台上遭到黑客攻擊。損失約為15,000美元。攻擊交易是：https：//bscscan.com/tx/0x2902f93a0e0e32893b6d5c907ee7ee7bb5dabc4593093efa6dbc6dbc6e6ba49f855c27f61

Attack and incident analysis

攻擊和事件分析

Principle of Four.meme

四分之一的原則

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，類似於Pump.Fun。類似啟動板平台的三個主要階段：

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

•階段1：用戶通過自定義其姓名，徽標，描述，社交帳戶（可選）等來創建模因。

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

•第2階段：其他用戶可以在平台上買賣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階段：當Memecoin的市場價值達到一定閾值（24 BNB）時，它將遷移到DEX（Pancakeswap）

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

下面，我們仔細研究了每個階段的具體技術細節。

Phase 1

階段1

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

在啟動板平台上，用戶填寫了他們想通過界面創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:

填寫表格後，支付處理費，以完成鏈接鏈合同的創建。當然，該合同是由LaunchPad的正式合同構成的，因此創建的ERC-20代幣的所有者也是Launchpad的正式合同。讓我們以四分之一的方式來看看Memecoin創建的示例。

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，用戶支付處理費，啟動板官方合同完成了Memecoin ERC-20代幣合同的部署，而MINT則為1,000,000,000個初始資金（預計Memecoin的Virtual Pool池預計為30 BNB）。

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

然後，我們看到創建令牌的所有者也是Launchpad官方網站的智能合同。

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.

這意味著，儘管用戶在啟動板上創建了Memecoin，但鏈條上的ERC-20合同的所有者不是用戶。這可以防止惡意行為（例如用戶自己鑄造）。一旦將Memecoin智能合約部署在鏈條上，它將進入第二階段，平台上的所有用戶都可以買賣。

Phase 2

第2階段

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.

平台上的其他用戶可以通過平台買賣，但是買賣後的代幣不能通過轉移轉移給其他用戶。我們可以查看鏈條上的ERC-20令牌的源代碼。

In _beforeTokenTransfer, the transfer is restricted by the parameter _mode

在_beforetokentransfer中，傳輸受參數_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.

在這一點上，我們可以看到，與令牌相對應的_mode是1階段1，它是mode_transfer_renter，限制了第三方轉移。

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.

這是為了防止OTC對價格的影響。購買和銷售時，最終合同將_mode首先設置為2，然後使用轉移將其轉移給用戶。傳輸完成後，將_mode設置為1，以限​​制其他用戶傳輸。購買後完成Memecoin的轉移。

Phase 3

階段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.

當Memecoin的市場價值達到24 BNB時，粘結曲線過程將達到100％。 LaunchPad將將其餘20％的Memecoin和24 BNB遷移到Dex Pancakeswap。此時，第3階段已正式完成。以下交易是發射台將Memecoin遷移到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:

我們可以看到，首先，LaunchPad官員將Memecoin的模具設置為0，即Mode_normal，允許用戶進行非處方交易。然後，LaunchPad官員創建了一對Memecoin和WBNB的交易，最終增加了235億枚（費用為0.5億美元），並在交易對中增加了235億美元的銷售。增加流動性的價格為SQRTPRICEX96 = 2716959999998237907265358521。因為SQRTPRICEX96的計算公式如下：

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

因此，添加流動性時該模因的價格為0.0000001175 WBNB，也可以通過除以2來獲得