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TakeOver | Jan 22, 2023

Introduction

Welcome to my another writeup! In this TryHackMe TakeOver room, you’ll learn: Subdomain enumeration, virtual host enumeration, inspecting SSL certificate in the browser! Without further ado, let’s dive in.

Background

This challenge revolves around subdomain enumeration.

Difficulty: Easy

Hello there,

I am the CEO and one of the co-founders of futurevera.thm. In Futurevera, we believe that the future is in space. We do a lot of space research and write blogs about it. We used to help students with space questions, but we are rebuilding our support.

Recently blackhat hackers approached us saying they could takeover and are asking us for a big ransom. Please help us to find what they can takeover.

Our website is located at https://futurevera.thm

Hint: Don’t forget to add the MACHINE_IP in /etc/hosts for futurevera.thm ; )

Service Enumeration

As usual, scan the machine for open ports via rustscan!

Rustscan:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|12:02:55(HKT)]
└> export RHOSTS=10.10.182.53  
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|12:03:01(HKT)]
└> rustscan --ulimit 5000 -b 4500 -t 2000 --range 1-65535 $RHOSTS -- -sC -sV -oN rustscan/rustscan.txt
[...]
PORT    STATE SERVICE  REASON         VERSION
22/tcp  open  ssh      syn-ack ttl 63 OpenSSH 8.2p1 Ubuntu 4ubuntu0.4 (Ubuntu Linux; protocol 2.0)
| ssh-hostkey: 
|   3072 dd29a70c05691ff6260ad928cd40f020 (RSA)
| ssh-rsa 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
|   256 cb2ea86d0366e970eb96e1f5ba25cb4e (ECDSA)
| ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBKQJTJFkvkwNTQLf9L+hjby2vSMriTeszWldCj+y2TDnTJpyvG1KvBlbzOPuFai3cxpZS/Y0/yU3JxK37I9T6cI=
|   256 50d34ba8a24d1d79e17dacbbff0b2413 (ED25519)
|_ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIF1HW9ff2E4eEhE6FZYXtcpuWX46Kg80Hl22peqirx25
80/tcp  open  http     syn-ack ttl 63 Apache httpd 2.4.41 ((Ubuntu))
| http-methods: 
|_  Supported Methods: GET HEAD POST OPTIONS
|_http-server-header: Apache/2.4.41 (Ubuntu)
|_http-title: Did not follow redirect to https://futurevera.thm/
443/tcp open  ssl/http syn-ack ttl 63 Apache httpd 2.4.41 ((Ubuntu))
|_ssl-date: TLS randomness does not represent time
| tls-alpn: 
|_  http/1.1
|_http-server-header: Apache/2.4.41 (Ubuntu)
| http-methods: 
|_  Supported Methods: POST OPTIONS HEAD GET
|_http-title: FutureVera
| ssl-cert: Subject: commonName=futurevera.thm/organizationName=Futurevera/stateOrProvinceName=Oregon/countryName=US/localityName=Portland/organizationalUnitName=Thm
| Issuer: commonName=futurevera.thm/organizationName=Futurevera/stateOrProvinceName=Oregon/countryName=US/localityName=Portland/organizationalUnitName=Thm
| Public Key type: rsa
| Public Key bits: 2048
| Signature Algorithm: sha256WithRSAEncryption
| Not valid before: 2022-03-13T10:05:19
| Not valid after:  2023-03-13T10:05:19
| MD5:   2e8d60976b23188c06d5f2cd8defdd3a
| SHA-1: 8023fcfc5e63a29b3d5eeaaf8f708b35d8ebc120
| -----BEGIN CERTIFICATE-----
| MIIDuzCCAqOgAwIBAgIUMx0OgCh/xob6nWlsHR+iKDXKZRkwDQYJKoZIhvcNAQEL
| BQAwbTELMAkGA1UEBhMCVVMxDzANBgNVBAgMBk9yZWdvbjERMA8GA1UEBwwIUG9y
| dGxhbmQxEzARBgNVBAoMCkZ1dHVyZXZlcmExDDAKBgNVBAsMA1RobTEXMBUGA1UE
| AwwOZnV0dXJldmVyYS50aG0wHhcNMjIwMzEzMTAwNTE5WhcNMjMwMzEzMTAwNTE5
| WjBtMQswCQYDVQQGEwJVUzEPMA0GA1UECAwGT3JlZ29uMREwDwYDVQQHDAhQb3J0
| bGFuZDETMBEGA1UECgwKRnV0dXJldmVyYTEMMAoGA1UECwwDVGhtMRcwFQYDVQQD
| DA5mdXR1cmV2ZXJhLnRobTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEB
| AKZio9bT9ebOivcm+9xKKCUAobE2cdU5VFbi1Ve7oxsSGKWWEcsQlUn7tFj1jjKq
| hWDMZXxEW6aN3jU5p5zF6ATmwIuvNQqwZOaK8iKjXs8IWEBIQyz/iKBF6deWrN+8
| II+whTaSberFaND2G0VchB7OrOu/mlP1KNhm2kEKwak7YHxvFkSp7Nmu2yTQAnyp
| WK2CBh3tdeGSq7/lyo8W3la/kPKhb4lmtBMS/tKPFslMxlOv0cSbNsvFVgJQ7jti
| OZKPo/DAeaFIFB/32HocscQXM2VdQNXnQQ6M1cbBNskYWzvwp6di+wYzjjCWtM4o
| Rg+3c/k5hqkEftEiwV7xAXcCAwEAAaNTMFEwHQYDVR0OBBYEFD23WEwlBMTDTpWI
| 0eMU0IMaJyPJMB8GA1UdIwQYMBaAFD23WEwlBMTDTpWI0eMU0IMaJyPJMA8GA1Ud
| EwEB/wQFMAMBAf8wDQYJKoZIhvcNAQELBQADggEBACu3W2VV8zRdD4M7oUWN8S6f
| lM1z8aCkSckgFDEX7jtyJjWMQVwPizKkX17XQs6EgnWqD/PVt2Tf9dRhUH6FQmTK
| qh35hnsSOdO3sQB8CnQ3SnlbeUYXY2mY/aUhz/lAkx6mURGuSen8BSbuL4mcm5Dk
| AXxfa+SHc5XAjuYSlXVUSPy8noqFOLxvcGz+zPN2RQYwQkMDgQtUX2n0VcjwgTLN
| bEuEm210+IGPX+ZEQWsnSSmz0SyUryBwc5BsjMaFUdAncxEBKCn1p4oN8gm6NQ32
| FHFbghTgLgMTahuLWpXdeuVF87+pHUlroRHdgblQtb2wSwqVaDGHaLFiZcUMv/Y=
|_-----END CERTIFICATE-----
Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel

According to rustscan result, we have 3 ports are opened:

Open Port Service
22 OpenSSH 8.2p1 Ubuntu
80 Apache httpd 2.4.41 ((Ubuntu))
443 Apache httpd 2.4.41 ((Ubuntu))

HTTP on Port 80

Adding a new host to /etc/hosts:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|12:03:39(HKT)]
└> echo "$RHOSTS futurevera.thm" >> /etc/hosts

Home page:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|12:05:30(HKT)]
└> curl -v http://futurevera.thm/ 
*   Trying 10.10.182.53:80...
* Connected to futurevera.thm (10.10.182.53) port 80 (#0)
> GET / HTTP/1.1
> Host: futurevera.thm
> User-Agent: curl/7.87.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 302 Found
< Date: Sun, 22 Jan 2023 04:05:31 GMT
< Server: Apache/2.4.41 (Ubuntu)
< Location: https://futurevera.thm/
< Content-Length: 0
< Content-Type: text/html; charset=UTF-8
<

When we go to /, it redirects me to the HTTPS one.

HTTPS on Port 443

Home page:

Accept the SSL self signed certificate:

It seems like this website is a Bootstrap template page.

In the rustscan + nmap scanning result, we found this:

| ssl-cert: Subject: commonName=futurevera.thm/organizationName=Futurevera/stateOrProvinceName=Oregon/countryName=US/localityName=Portland/organizationalUnitName=Thm
| Issuer: commonName=futurevera.thm/organizationName=Futurevera/stateOrProvinceName=Oregon/countryName=US/localityName=Portland/organizationalUnitName=Thm

Hmm… No “Subject Alt Names”? (A common method to enumerate subdomains)

Speaking of subdomain, let’s fuzz subdomains via ffuf in HTTP port:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:22:12(HKT)]
└> ffuf -w /usr/share/seclists/Discovery/DNS/bitquark-subdomains-top100000.txt -u http://futurevera.thm/ -H "Host: FUZZ.futurevera.thm" -fw 1 -t 100
[...]
portal                  [Status: 200, Size: 69, Words: 9, Lines: 2, Duration: 4620ms]
payroll                 [Status: 200, Size: 70, Words: 9, Lines: 2, Duration: 240ms]

Let’s add those 2 subdomains to /etc/hosts:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:24:02(HKT)]
└> nano /etc/hosts                               
10.10.182.53 futurevera.thm portal.futurevera.thm payroll.futurevera.thm

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:24:56(HKT)]
└> curl http://portal.futurevera.thm/    
<h1> portal.futurevera.thm is only availiable via internal VPN </h1>
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:25:00(HKT)]
└> curl http://payroll.futurevera.thm/
<h1> payroll.futurevera.thm is only availiable via internal VPN </h1>

Umm… Those 2 subdomains only availiable via internal VPN…

Now, we can fuzz subdomains in HTTPS port.

Since the website is related to “space research”, “blog”, etc. Let’s build a custom wordlist via cewl:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|12:57:03(HKT)]
└> cewl https://relatedwords.io/space-research -d 1 -w wordlist.txt
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|12:58:16(HKT)]
└> cewl https://relatedwords.io/space -d 1 >> wordlist.txt
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:00:07(HKT)]
└> cewl https://futurevera.thm/ -d 1 >> wordlist.txt
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:10:02(HKT)]
└> cewl https://relatedwords.io/blog -d 1 >> wordlist.txt                 
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:12:36(HKT)]
└> cewl https://relatedwords.io/rebuilding -d 1 >> wordlist.txt
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:14:01(HKT)]
└> cewl https://relatedwords.io/support -d 1 >> wordlist.txt   
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:15:35(HKT)]
└> cewl https://relatedwords.io/future -d 1 >> wordlist.txt 

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:34:23(HKT)]
└> ffuf -w wordlist.txt -u https://$RHOSTS/ -H "Host: FUZZ.futurevera.thm" -fs 4605 -t 100 
[...]
blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 267ms]
support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 251ms]
blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 245ms]
Blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 247ms]
support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 242ms]
blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 240ms]
support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 284ms]
support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 241ms]
blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 245ms]
Support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 239ms]
blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 239ms]
support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 241ms]

Note: Don’t use https://futurevera.thm/ in -u flag.

Again, add those 2 subdomains to /etc/hosts:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:36:46(HKT)]
└> nano /etc/hosts
10.10.182.53 futurevera.thm portal.futurevera.thm payroll.futurevera.thm blog.futurevera.thm support.futurevera.thm

blog:

In this subdomain, we can see there is a blog post:

However, nothing weird.

support:

Hmm… Nothing.

We can also use cewl again to build a new custom wordlist:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:36:49(HKT)]
└> cewl https://blog.futurevera.thm/ -w wordlist_1.txt
┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:41:21(HKT)]
└> cewl https://support.futurevera.thm/ >> wordlist_1.txt

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:40:42(HKT)]
└> ffuf -w wordlist_1.txt -u https://$RHOSTS/ -H "Host: FUZZ.futurevera.thm" -fs 4605 -t 100 
[...]
Blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 243ms]
blog                    [Status: 200, Size: 3838, Words: 1326, Lines: 81, Duration: 247ms]
Support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 238ms]
support                 [Status: 200, Size: 1522, Words: 367, Lines: 34, Duration: 242ms]

Nothing new.

Now, just like how we inspect the SSL cert in https://futurevera.thm, we can see is there any “Subject Alt Names” field:

Nothing in blog.

How about support?

Found “Subject Alt Names” field!

Finally, add that subdomain to /etc/hosts:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:54:08(HKT)]
└> cat /etc/hosts
10.10.182.53 futurevera.thm portal.futurevera.thm payroll.futurevera.thm blog.futurevera.thm support.futurevera.thm secrethelpdesk934752.support.futurevera.thm

After fumbling around, the secrethelpdesk934752 subdomain in support in top level domain futurevera.thm is in HTTP port:

┌[root♥siunam]-(~/ctf/thm/ctf/TakeOver)-[2023.01.22|13:58:47(HKT)]
└> curl -v http://secrethelpdesk934752.support.futurevera.thm 
*   Trying 10.10.182.53:80...
* Connected to secrethelpdesk934752.support.futurevera.thm (10.10.182.53) port 80 (#0)
> GET / HTTP/1.1
> Host: secrethelpdesk934752.support.futurevera.thm
> User-Agent: curl/7.87.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 302 Found
< Date: Sun, 22 Jan 2023 05:58:52 GMT
< Server: Apache/2.4.41 (Ubuntu)
< Location: http://flag{Redacted}.s3-website-us-west-3.amazonaws.com/
< Content-Length: 0
< Content-Type: text/html; charset=UTF-8
<

We found the flag!

Conclusion

What we’ve learned:

  1. Enumerating Subdomains/Virtual Hosts Via ffuf
  2. Creating Custom Wordlist Via cewl
  3. Inspecting SSL Certificate In The Browser