Hack The Box / Lightweight

3 minute read

Lightweight is our tenth machine in the OSCP list provided by NetSec Focus! Very interesting machine due to the enumeration given through LDAP, its HTTP services, and the privilege escalation with capabilities. This is the tenth blog before my third attempt to the OSCP exam, so let’s get to it!

Information Gathering

Nmap Scan

So, we start with a nmap scan to check what ports are open and what services are running in this machine.

nmap -sC -sV -p- -oN scan.nmap

nmap scan

There are couple services running such as SSH, HTTP, and LDAP. Sounds like the enumeration is going to be quiet interesting this time.

Enumerating LDAP

There are different techniques to enumerate this service where one of them was using different nmap scripts that are going to look for a service and enumerate it according the scripts given, or the usage of ldapsearch which is also good and clear. This time we are going to enumerate LDAP with nmap scripts.

nmap -p 389 --script=ldap-brute.nse,ldap-novell-getpass.nse,ldap-rootdse.nse,ldap-search.nse

nmap scan nmap scan

Ok, according the results given by nmap, there are different things to look, such as the users which are ldapuser1 and ldapuser2, and there are some hashes, but unfortunately we are not able to crack them.

Directory Brute Force

After enumerating LDAP, it’s time to see what is to find in HTTP, but trying gobuster didn’t give many results because the machine was protected against brute force, which means that we got banned multiple times because of trying to do directory brute force. In spite of the protection of the website, we could get some results that were good enough to continue with the process.

gobuster dir -u -w /usr/share/dirbuster/wordlists/directory-list-lowercase-2.3-medium.txt -t 5 -x .php, .txt, .py

nmap scan

After checking with the browser the content from the webpage this is what we found.

nmap scan

And, after going to user.php, we found information saying that we can login through SSH using our IP as a username and password, great!

nmap scan

SSH Login & Privileges Escalation

Effectively, the login was successful providing credentials as our IP as username and password.

nmap scan

So, at the time to escalate privileges, the usage of LinEnum was crucial and useful because we found some capabilities that we could execute with our user. The capability was related with usage of tcpdump which means that we can capture traffic in the target machine.

nmap scan

To escalate privileges, we execute tcpdump, wait some time while it captures some traffic packets, and once the packets have been captured, it’s time to analyze the traffic in our localhost with wireshark. This is the command to capture the traffic within the target machine.

tcpdump -i any -w captured.pcap 

nmap scan

Once the traffic has been captured, we can transfer the file through SCP and analyze it with wireshark.

nmap scan

Great, we found credentials in LDAP protocol. So, user:ldapuser2 and password:8bc8251332abe1d7f105d3e53ad39ac2

User Flag

After obtaining the credentials, it’s time to log in and get the user flag!

nmap scan

The user has been owned.

Privilege Escalation To ldapuser1

In the home directory from user ldapuser2 there is a file called backup.7z, interesting name, right? So, we can transfer this file through base64.

  • From target machine: base64 backup.7z nmap scan nmap scan

Copy the result in the localhost, and name it backup.7z.b64, and decode it. After decoding it it’s time to crack the password because we are required to use a password to read the file.

Cracking backup.7z

To crack backup.7z there is a tool-kit from John that can extract the hash from a 7z file and cracked.

 perl 7z2john.pl backup.7z  > backup
 john backup -w=/usr/share/wordlists/rockyou.txt

nmap scan

and we got the password which is delete.

nmap scan

Once we extract the files from backup.7z we see a file called status.php which contains the passwords to get ldapuser1.

nmap scan

Great, so we just su ldapuser2 using the password found which is f3ca9d298a553da117442deeb6fa932d.

Privileges Escalation to Root

Using LinEnum we found other capability which was related to openssl, and there was a openssl binary in the home folder from ldapuser1 which means that we might read, and write files through openssl.

nmap scan

Now, having this flaw, we can extract the file /etc/shadow from root

./openssl aes-256-cbc -d -a -in shadow.enc -out shadow

nmap scan

Knowing that we can modify the hash from root in the shadow file, set our password and write it, so we can login to root with our own password.

./openssl aes-256-cbc -a -salt -in shadow -out shadow.enc

nmap scan

And, we get to root with the password that we have set!

nmap scan

And let’s read the flag.

nmap scan

We have owned Lightweight!

To Conclude

To be honest the machine was challenging and there was a lot to learn. The privileges escalation process was exotic in my own experience due to my lack of knowledge of capabilities in windows. Saying that, the learning experience was fruitful with this machine.

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