acCOMplice

Your COM hijacking accomplice

Author: David Tulis (@kafkaesqu3)

Overview

This repository contains code samples and proofs-of-concept for exploring COM hijacking. COM hijacking is a Windows post exploitation technique, which can be used for persistence or defense evasion.

For more information on the COM interface, how to find hijacks, and techniques for abusing a hijack, please refer to the presentation given at Derbycon 9, COM Hijacking Techniques.

• Slides: https://www.slideshare.net/DavidTulis1/com-hijacking-techniques-derbycon-2019
• Presentation: https://www.youtube.com/watch?v=pH14BvUiTLY

Project

• COMHijackToolkit: Powershell script containing helper scripts for dealing with COM hijacks. Quick highlights:
  • Extract-HijackableKeysFromProcmonCSV: parses a Procmon CSV export for hijackable objects
  • Hijack-CLSID: Hijacks a CLSID with a given DLL
  • Hijack-MultipleKeys: Hijacks multiple CLSDs concurrently with a given DLL. This is useful for finding CLSIDs which are activated often
• InjectionTemplates: 3 templates demoed at Derbycon presentation
  • Create a new process with CreateProcess
  • Inject into an existing process with CreateRemoteThread
  • Measure thread lifetimes in current process using CreateThread
• COMinject: Proof of concept demonstrating how COM hijacks can be used to accomplish process injections/migrations
• masterkeys.csv: Some keys for you to play with
• procmon-filters: Filters for Procmon to aid in hijack identification and exploitation

Examples

COMHijackToolkit

Powershell script containing helper scripts for dealing with COM hijacks. Highlights:

Show all COM object CLSIDs and the location of the implementation on disk

$keys = Get-CLSIDRegistryKeys -RegHive HKCR
$results = $keys | % {$guid = Extract-GUIDFromText $_; Map-GUIDToDLL -guid $guid 2> $null }

Conduct a survey of CLSIDs on a system

$HKCR_keys = Get-CLSIDRegistryKeys -RegHive HKCR
$HKCR_keys | where-object {$_ -like "*inprocserver"} | Measure-Object
$HKCR_keys | where-object {$_ -like "*inprocserver32"} | Measure-Object
$HKCR_keys | where-object {$_ -like "*localserver"} | Measure-Object
$HKCR_keys | where-object {$_ -like "*localserver32"} | Measure-Object

$HKLM_keys = Get-CLSIDRegistryKeys -RegHive HKLM
$HKLM_keys | Measure-Object
$HKCU_keys = Get-CLSIDRegistryKeys -RegHive HKCU
$HKCU_keys | Measure-Object

explorer:{69486DD6-C19F-42e8-B508-A53F9F8E67B8}
explorer:{9E175B6D-F52A-11D8-B9A5-505054503030}
explorer:{30CC9D06-7E62-4966-9777-BC3442E788BD}
explorer:{3eef301f-b596-4c0b-bd92-013beafce793}
explorer:{682159d9-c321-47ca-b3f1-30e36b2ec8b9}
explorer:{6B3B8D23-FA8D-40B9-8DBD-B950333E2C52}
explorer:{9aa46009-3ce0-458a-a354-715610a075e6}
explorer:{9BA05972-F6A8-11CF-A442-00A0C90A8F39}
explorer:{AC36A05C-FB95-4C7A-868C-A43CC8D2D926}
explorer:{B52D54BB-4818-4EB9-AA80-F9EACD371DF8}
explorer:{c2f03a33-21f5-47fa-b4bb-156362a2f239}

Find CLSIDs referencing a DLL which does not exist on the system:

Find-MissingLibraries

InjectionTemplates

3 proof-of-concept templates for COM hijack abuse, as demonstrated in the Derbycon 9 presentation:

• HijackDLL-Process: Create a new process when DLL is loaded
• HijackDLL-CreateRemoteThread: Perform thread injection technique using CreateRemoteThread API call when DLL is loaded
• HijackDLL-Threads: Useful for measuring lifetime of a threads started in the DLL after a hijack

COMinject

Proof of concept to show how COM hijacking can be used for process injections:

• COMInjectDotNet: Proof of concept client which will inject a DLL into a supported process via COM hijack
• COMInjectTarget: The target library to inject into a process

The first step is to perform the hijack:

COMInjectDotNet.exe chrome.exe C:\COM\COMInjectTarget.dll

The hijack won't trigger immediately, and may require the application to be started (if not currently running), or some basic application actions. There are probably some better CLSIDs that trigger more often, but these are good enough.

The COMInjectTarget.dll will log its progress to a log file in C:\COM. This appears more stable than using something like AllocConsole from within another process and just printing to the console.

The following shows the injected DLL running from within the main chrome.exe process:

[*] chrome pid=9104 ppid=4900 (count 0)
[*] chrome pid=9104 ppid=4900 (count 1)
[*] chrome pid=9104 ppid=4900 (count 2)
[*] chrome pid=9104 ppid=4900 (count 3)
[*] chrome pid=9104 ppid=4900 (count 4)
[*] chrome pid=9104 ppid=4900 (count 5)

The currently supported processes are:

• explorer (default)
• chrome
• excel
• word
• outlook

References and credits

To learn more about COM and COM hijacks:

• Leo Loobeek (@leoloobeek):
  • COMProxy, which I borrowed code heavily from
  • Proxying COM For Stable Hijacks
• Matt Nelson (@enigma0x3):
  • Userland Persistence with Scheduled Tasks and COM Handler Hijacking
• The @bohops series on COM hijacks:
  • Abusing the COM Registry Structure: CLSID, LocalServer32, & InprocServer32
  • Abusing the COM Registry Structure (Part 2): Hijacking & Loading Techniques
• James Forshaw (@tiraniddo):
  • Having Fun with COM
  • COM in 60 seconds
  • OleViewDotNet
• Casey Smith (@subtee) + @enimga0x3:
  • Windows Operating System Archaeology (slides, code)