DOS attack intro

NFT Project/testNFT.sol

@@ -26,4 +26,3 @@ function safeMint(address to) public onlyOwner{
     totalSupply++;
     _mint(to,tokenID);
 }
-}

englishAuction.sol

@@ -0,0 +1,47 @@
+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.7;
+
+contract EnglishAuction{
+    address payable public seller;
+    uint256 public timeToEnd;
+    bool public running;
+
+    address public highestBidder;
+    uint public highestBid;
+
+    constructor(){
+        seller = payable(msg.sender);
+
+
+    }
+
+    function startAuction() public{
+        require(!running);
+        require(seller == msg.sender);
+
+        running = true;
+        timeToEnd = block.timestamp + 1 minutes;
+
+    }
+
+    function bid() public payable{
+        require(running);
+
+        require(msg.value > highestBid);
+
+        payable(highestBidder).transfer(highestBid);
+
+        highestBidder = msg.sender;
+        highestBid = msg.value;
+
+    }
+
+    function win() public{
+        require(running);
+        require(timeToEnd <= block.timestamp);
+
+        running = false;
+        seller.transfer(highestBid);
+    }
+}

hackEnglishAuction.sol

@@ -0,0 +1,27 @@
+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.7;
+
+interface IEnglishAuction{
+    function bid() external payable;
+}
+
+contract auctionHack{
+    IEnglishAuction public auctionContrcat;
+
+    constructor(address addy){
+        auctionContrcat = IEnglishAuction(addy);
+    } 
+
+    function bid() public payable{
+        auctionContrcat.bid{value: msg.value}();
+    }
+
+    fallback() external payable{
+
+    }
+
+    receive() external payable{
+
+    }
+}