# UsoDllLoader | Windows Weaponizing Privileged File Writes With The Update Session Orchestrator Service

**URL:** <https://onehack.st/t/usodllloader-windows-weaponizing-privileged-file-writes-with-the-update-session-orchestrator-service/94953>\
**Category:** Tools & Scripts\
**Tags:** privacy, cracking, windows\
**Created:** [July 2, 2020, 11:21am UTC](https://onehack.st/t/usodllloader-windows-weaponizing-privileged-file-writes-with-the-update-session-orchestrator-service/94953 "2020-07-02T11:21:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![BlueHacker](https://onehack.st/user_avatar/onehack.st/bluehacker/32/174721_2.png) [@BlueHacker](https://onehack.st/u/BlueHacker)\
**Post date:** [July 2, 2020, 11:21am UTC](https://onehack.st/t/usodllloader-windows-weaponizing-privileged-file-writes-with-the-update-session-orchestrator-service/94953/1 "2020-07-02T11:21:21Z")

</div>

![](https://raw.githubusercontent.com/itm4n/UsoDllLoader/master/screenshots/UsoDllLoader.gif)

**2020-06-06 Update:** this trick no longer works on the latest builds of **Windows 10 Insider Preview**. This means that, although **it still works on the mainstream version of Windows 10** , you should expect it to be _patched_ in the coming months.

**Description**  
This PoC shows **a technique** that can be used to **weaponize privileged file write vulnerabilities** on Windows. It provides an alternative to the DiagHub DLL loading “exploit” found by James Forshaw (a.k.a. [@tiraniddo](https://twitter.com/tiraniddo)), which was fixed by Microsoft starting from build version 1903.

**TL;DR**  
Starting from Windows 10, Microsoft introduced the `Update Session Orchestrator` service. **As a regular user** , you can interact with this service using COM, and start an “update scan” (i.e. check whether updates are available) or start the download of pending updates for example. There is even an undocumented built-in tool called `usoclient.exe` , which serves that purpose.  
From an attacker’s standpoint, this service is interesting because it runs as `NT AUTHORITYSystem` and it tries to load a **non-existent DLL** ( `windowscoredeviceinfo.dll` ) **whenever an Update Session is created**.  
This means that, if we found a privileged file write vulnerability in Windows or in some third-party software, we could copy our own version of `windowscoredeviceinfo.dll` into `C:WindowsSytem32` and then have it loaded by the USO service to get arbitrary code execution as `NT AUTHORITYSystem` .  
For more information:  
Part 1 – [https://itm4n.github.io/usodllloader-part1/](https://itm4n.github.io/usodllloader-part1/)  
Part 2 – [https://itm4n.github.io/usodllloader-part2/](https://itm4n.github.io/usodllloader-part2/)

**Build the PoC**

**Content**  
This solution is composed of two projects: **WindowsCoreDeviceInfo** and **UsoDllLoader**.

- **WindowsCoreDeviceInfo**

It provides a PoC DLL that will start a bind shell on port 1337 (localhost only), whenever the `QueryDeviceInformation()` function is called. That’s the name of the function used by the USO workers.

- **UsoDllLoader** (optional)

It’s a stripped-down version of `usoclient.exe` . It can be run as a regular user to interact with the USO service and have it load `windowscoredeviceinfo.dll` . Then, it will try to connect to the bind shell. In case of errors, please read the “Known issues” section.

**Build the solution**  
The solution is already preconfigured so compiling should be easy. I’m using **Visual Studio 2019**. It might not work with older versions.

1. Select `Release` config and `x64` architecure.
2. Build solution.
3. Output: the DLL `.x64ReleaseWindowsCoreDeviceInfo.dll` and the loader `.x64ReleaseUsoDllLoader.exe` .

**Test**

**Usage 1 – UsoDllLoader**  
For testing purposes, you can:

1. **As an administrator** , copy `WindowsCoreDeviceInfo.dll` to `C:WindowsSystem32` .
2. Use the loader as a regular user.
3. Hopefully enjoy a shell as `NT AUTHORITYSYSTEM` .

**Usage 2 – UsoClient**  
If `UsoDllLoader.exe` fails, you can do the above _manually_ .

1. **As an administrator** , copy `WindowsCoreDeviceInfo.dll` to `C:WindowsSystem32` .
2. Use the command `usoclient StartInteractiveScan` as a regular user. Note that you won’t get any feedback from the command.
3. Download netcat for Windows and use the command `nc.exe 127.0.0.1 1337` to connect to the bindshell.

**Known issues**

- **Pending updates**

This method will probably fail if one or several updates are waiting to be installed, or if updates are being installed.

- **RPC errors**

Depending on the version of Windows, `UsoDllLoader.exe` might **fail with various error codes**. I didn’t investigate these issues too much. The reason for this is that it’s only a PoC, which I developped for convenience. **What matters the most is the DLL** , not the loader. See “Usage 2” for more details.

## GitHub:

[https://github.com/itm4n/UsoDllLoader](https://github.com/itm4n/UsoDllLoader)