hackme: 1: Vulnhub Walkthrough

Hack me is another CTF challenge and credit goes to Avraham Cohen for designing this VM. Here you need to identify bug to get reverse shell connection of the machine and try to access root shell. This VM can be downloaded from given below link and its level is set to easy for beginners.

https://www.vulnhub.com/entry/hackme-1,330/

Penetration Testing Methodology

Scanning

·         Netdiscover

·         Nmap

Enumeration

·         Using burp suite

Exploitation

·         Using sqlmap

·         Using dirb

Privilege Escalation

·         Abusing SUID Binary

Walkthrough

Scanning

First, we will start with the scanning using net discover command and identifying the host IP address. Here we found that host IP 192.168.1.108 is up.

netdiscover

nmap -A 192.168.1.108

Now we will use Nmap tool for the port enumeration where we have found that port 22 and 80 is open.

Enumeration

Now we will try to connect through port 80 where we have found a login page.

As we can see here the sign-up option so we will create a new account with a username and password.

And after creating a new account; we have successfully logged in

Simultaneously we have intercepted the request of this page using burp suite.

Exploitation

We have saved this request in a text file named sql.txt and now we will run sqlmap to extract the data base information from this request file.

sqlmap -r sql.txt –dbs --batch

Here we have got data base names from which we have selected webapphacking data base from which we want to extract the data.

sqlmap -r sql.txt -D webapphacking –dump-all --batch

As we can see that it has given so many usernames and passwords except one which is super admin; only hash value is provided of super admin.

To crack this hash value, we will go to online hash decrypter and will copy the request and paste it to encrypt this hash value. And we can see that it has given us the password in encrypted form which is Uncrackable.

Now we will logged in through super admin with the password which we have found above and we have successfully logged in.

192.168.1.108/welcomeadmin.php

Here we have found an option of file upload where we will upload our malicious file to get the reverse shell of the machine.

Thus, I grabbed a malicious file “php-reverse-shell” from inside /usr/share/webshells/php and modify the listening i.e. Kali Linux IP and named it shell.php.

When we will browse again we fill find that shell.php is uploaded successfully.

Since we don’t know the location of shell.php directory; so, we will take the help of dirb command to find the exact location shell.php and it has shown us that it is inside the uploads.

dirb http://192.168.1.108

Now as we will execute /uploads/shell.php and we will get the session on netcat which is simultaneously running on the terminal.

Privilege Escalation

Great!! We successfully get the netcat session with low privilege shell , now we will search for the SUID enabled binaries by which we can get the root privilege shell, so for this purpose we will use the find command which will tell us that which has SUID permissions.

nc -lvp1234

find / -perm -u=s -type f 2>/dev/null

Here we got to know that /legacy directory has SUID permissions; so, we will first go inside the legacy directory and there we will execute “touchmenot” file and we will get the root access. We will check the id and we can see that we are logged in as root which reflects that we have completed our CTF successfully.

cd /home/legacy

./touchmenot

id