太湖杯writeup

• 2020 年 11 月 22 日
• 筆記
• CTF, writeup

“太湖杯”线上赛和决赛都结束了，放上我们的线上赛web题的writeup

CheckInGame

checkInGame本题是个js游戏

设置个断点后，之后修改时间即可，然后把游戏玩完就行。

ezWeb

本题是模板注入，过滤了{}和””，用︷︸和无引号的payload绕过就行了

CrossFire

联合注入双写绕过。load_file直接读源码。

<?php
    error_reporting(0);
    session_start();
    include('config.php');

    $upload = 'upload/'.md5("shuyu".$_SERVER['REMOTE_ADDR']);
    @mkdir($upload);
    file_put_contents($upload.'/index.html', '');
    
    if(isset($_POST['submit'])){
        $allow_type=array("jpg","gif","png","bmp","tar","zip");
        $fileext = substr(strrchr($_FILES['file']['name'], '.'), 1);
        if ($_FILES["file"]["error"] > 0 && !in_array($fileext,$type) && $_FILES["file"]["size"] > 204800){
            die('upload error');
        }else{
            $filename=addslashes($_FILES['file']['name']);
            $sql="insert into img (filename) values ('$filename')";
            $conn->query($sql);
            $sql="select id from img where filename='$filename'";
            $result=$conn->query($sql);


            if ($result->num_rows > 0) {
                while($row = $result->fetch_assoc()) {
                    $id=$row["id"];
                }
            move_uploaded_file($_FILES["file"]["tmp_name"],$upload.'/'.$filename);
            header("Location: index.php?id=$id");
            }
        }
    }

    elseif (isset($_GET['id'])){
        $id=addslashes($_GET['id']);
        $sql="select filename from img where id=$id";
        $result=$conn->query($sql);
        if ($result->num_rows > 0) {
            while($row = $result->fetch_assoc()) {
                $filename=$row["filename"];
            }
        $img=$upload.'/'.$filename;
        echo "<img src='$img'/>";
        }
    }

    elseif (isset($_POST['submit1'])){
        $allow_type=array("jpg","gif","png","bmp","tar","zip");
        $fileext = substr(strrchr($_FILES['file']['name'], '.'), 1);
        if ($_FILES["file"]["error"] > 0 && !in_array($fileext,$type) && $_FILES["file"]["size"] > 204800){
            die('upload error');
        }else{
            $filename=addslashes($_FILES['file']['name']);
            move_uploaded_file($_FILES["file"]["tmp_name"],$upload.'/'.$filename);
            @exec("cd /tmp&&python3 /tar.py ".escapeshellarg('/var/www/html/'.$upload.'/'.$filename));
            }
        }
?>

config.php

$conn=mysqli_connect("localhost","root","root","shuyu"); 
if (mysqli_connect_error($conn))
{ 
    echo "???? MySQL ???: " . mysqli_connect_error(); 
} 
foreach ($_GET as $key => $value) {
	 $value= str_ireplace('\'','',$value);
	 $value= str_ireplace('"','',$value);
     $value= str_ireplace('union','',$value);
     $value= str_ireplace('select','',$value);
     $value= str_ireplace('from','',$value);
     $value= str_ireplace('or','',$value);
	 $_GET[$key] =$value;
 }
?>

完后文件上传结合目录穿越拿shellflag{332a580f-b254-48fd-91b4-1d4fb6ad14fb}

ezMd5

//122.112.253.121:10032/robots.txt

发现有个可疑目录，打开后是一个文件，明显是pwn题

然后利用栈溢出可以覆盖返回值username =240610708password=CCCCCCCCCCBBBBBBBBBBBBBBBBBBBBBBQNKCDZO