HackTheBox - Base Writeup

index

Enumeration

Top 1000 ports scan

nmap -sC -sV -oN nmap/initial 10.10.10.48

the result

nmap scan result

All ports scan

nmap -sC -sV -p- -oN nmap/all__ports 10.10.10.48

the result

nmap scan allports

Open Ports

both Nmap scan result shows the only port open are SSH and HTTP

Gobuster

gobuster dir -u http://10.10.10.48 -w /opt/SecLists/Discovery/Web-Content/raft-small-words.txt -x php.html -o Rgobuster

We’ve found couples of hidden directory
the result
- http://10.10.10.48/login/
- http://10.10.10.48/static/
- http://10.10.10.48/_uploaded/
let’s take a look at /login/ directory

directory listing

Config.php sounds fantastic but I can’t read them.
However, the file login.php.swp can be download.
well, let’s download that file and take a peek at it

login.php.swp

let’s strings that file out
the result

well, it is a piece of code on how the login form works
it’s just logic if-else statements but again my eye caught something else.

Strcmp bypass

php strcmp

Summary

Returns < 0 if string1 is less than string2; > 0 if string1 is greater than string2, and 0 if they are equal.

it compares the string1 and string2 . If they equal returns 0
Again we don’t know the password.
we can make it one of the strings into arrays because it will returns NULL
when NULL == 0 it will returns 0
Source

Foothold/Gaining Access

Devtools

Let’s navigate to the login page http://10.10.10.48/login/login.php. Now, we’ve learned how these login forms work. Let’s try strcmp bypass
First, I’m gonna insert something in those username and password fields.
Then, open up the Devtools and go to the Network tab.
Right-click and click on Edit and Resend
it should look like this.

devtools

Then edit the Request Body something like this
username[]=''&password[]=''
After that, click on Send and you should see the upload.php appears.

modify login request

Upload

Now, you have to do is Double-click on upload.php and you should greet by this page.

upload page

That means we successfully bypass the login.
So, I’m gonna upload the PHP reverse shell
I’m successfully uploaded. Remember those gobuster scans we did earlier. we’ve found the directory called _uploaded
Let’s navigate the URL and the file name. Hopefully, it will execute the revshell.

http://10.10.10.48/_uploaded/<filename>

shell as www-data

we’ve got the shell

config.php

I’m in. remember the file called config.php we’ve found earlier but sadly we can’t read it.
Now, it’s the time to read it. Let’s navigate into this directory
/var/www/html/login/. Then, read the config.php file

password in config.php

John

So, we’ve found the password.
Maybe this password belongs to the user on this system.
Let’s cat /etc/passwd

check user in /etc/password

we found one user name john.
Let’s try login as john with those password we’ve found.

change user to john

Great. Now, I’m John

User Flag

user flag

Privilege Escalation

OK. I’ve got the user password.
Let’s try to check the sudo permission this user got with this commands sudo -l
the result

check sudo permission

Well, Let’s try to become root
by running this command
Source
- GTFObins - find

sudo /usr/bin/find . -exec /bin/bash \; -quit

become root

Root Flag

root flag

Conclusion

I’ve learned a lot today. Do not expose anything on the internet. Make sure your website properly configure. If your website offers to upload something. Make it harder for an attacker to upload that related to security risks such as reverse shell. Once again, don’t use the same password. Oh before I forgot. Configure the user and the root properly.

I have a fun time doing this machine and I hope you guys do too. Bye ;)