Learn how I hijacked the explorer context menu to execute my beacon at each right click on a file/folder.


I get the idea to implement it and share it when I watched the video of @ParanoidNinja about Windows Context Menu (Right Click) COM Hijacking for Persistence. This is also an opportunity to talk about the COM hijacking technique if it’s still not clear to you. So let’s see how it works.

If you want to use it, feel free to do it and put a star :) -> ContextMenuHijack

What is COM ?

Component Object Model (COM) is object-oriented and an Application Binary Interface (ABI) and used in frameworks such as IExplorer, OLE, ActiveX, COM+, DCOM, MTS, MSMQ, IIS, IPP, RPC, DTC, MMC, DirectX. The COM architecture allows developers to create their own applications and share them with others.

When an application needs to use a COM object, it typically calls the CoCreateInstance function, which requests the Services Control Manager (SCM) to query registry keys like HKEY_LOCAL_MACHINE (HKLM), HKEY_CURRENT_USER (HKCU), and HKEY_CLASSES_ROOT (HKCR) for information about the registered classes of objects, including their ProgIDs, CLSIDs, and other attributes.

Functions like DllGetClassObject, DllUnregisterServer, DllRegisterServer, DllCanUnloadNow will be exported and used by the application. it’s a mandatory to have at least one exported function for COM Objects.

  • DllGetClassObject: creates instances of the objects in the DLL.
  • DllRegisterServer & DllUnregisterServer: registering and unregistering the COM components implemented by the DLL
  • DllCanUnloadNow: is optional but it’s used to determines whether it’s safe to unload the DLL from memory.

Explorer Context Menu Hijacking

IContextMenu & IShellExtInit interfaces

IShellExtInit and IContextMenu are interfaces in the Windows API that allow developers to extend the Windows shell and add custom functionality to the context menu that appears when users right-click on a file or folder in Windows Explorer or Desktop.

To use the IContextMenu interface to perform actions when the user right-clicks on a file or folder in File Explorer, we need to implement the IContextMenu::QueryContextMenu and IContextMenu::InvokeCommand methods in the shell extension but we don’t want to add any extensions so these 2 methods will just return true.

the IShellExtInit::Initialize method to receive information about the items that the user has selected. This method is called once for each right clicks and subsequently, the CreateThread function is called to create a new thread and execute our beacon.


Now, let’s talk a bit of IUnknown interface which is one of the most important interface for COM. It’s composed of QueryInterface method which is used to query an object for the set of interfaces it supports.


In this code, we are populating a QITAB table with the interfaces supported by the object. The QISearch function is then used to determine if the object supports the requested interface, and will return the interface pointer if it does.

If you wanna learn more about this here a good blog of @timmisiak

Shell Extension ContextMenuHandlers

The last important part of this is to register the context menu handler, all the magic is in DllRegisterServer. The RegisterInprocServer function is called to register the in-process COM server. This function takes 4 args including the CLSID of the object being registered and the threading model.

    hr = RegisterInprocServer( szModule, CLSID_FileContextMenuExt, L"ContextMenuHijack.FileContextMenuExt Class", L"Apartment" );
    if ( SUCCEEDED( hr ) ) {
        hr = RegisterShellExtContextMenuHandler( L"AllFilesystemObjects", CLSID_FileContextMenuExt, L"ContextMenuHijack.FileContextMenuExt" );

After registering the in-process COM server, RegisterShellExtContextMenuHandler is called to register the context menu handler in HKCR registry hive for all file system objects. The full path looks like that : HKEY_CLASSES_ROOT\AllFilesystemObjects\shellex\ContextMenuHandlers\{B7CDF620-DB73-44C0-8611-832B261A0107}

Put it all together

once you have administrator privileges, you just have to register the DLL file in the registry with regsvr32 :

regsvr32 "C:\path\to\ContextMenuHijack.dll"

And now you just have to wait that your target wants to interact with a file or folder by right-clicking on it and then you will have your beacon. This technique is still a bit risky because we don’t really know when it happens, it is purely based on human behavior. But whatever it was cool to reproduce.



  • this technique can be easily detected from the thread stack of explorer.exe or just simply from the registry with Cm kernel callbacks for example, it is up to you to use your own evasion tradecraft :) image