Update 15. 3. 2010: this technique will fail at the genuity verification step of setup with recent Security Essentials installers. So it doesn’t work anymore. (And I will not be writing an update of this post, because I have moral problems with bypassing genuity verifications, sorry.)

I was getting a lot of e-mail about my recent article on installing Microsoft Security Essentials on Windows Server. Because the article shows up pretty high on google when searching for “security essentials windows server”, people kept asking me for a step-by-step tutorial. Originally, I didn’t want to do it because if someone isn’t able to follow the brief instructions I wrote in the original article, he won’t be able to fix problems that might show up after installing updates to Security Essentials. But whatever. Fasten your seat belts because here it comes:

REMEMBER: THIS IS NOT SUPPORTED BY MICROSOFT. IF YOU FOLLOW THESE INSTRUCTIONS, YOUR COMPUTER MIGHT BECOME UNBOOTABLE, SECURITY ESSENTIALS MIGHT APPEAR THEY WORK BUT THEY SILENTLY WON’T. ALSO, NIGHT ELVES WILL EAT ALL GROCERIES FROM YOUR FRIDGE WHILE YOU SLEEP.

This will only work for 64bit versions of Windows Server.

1. Follow my original article up to (and including) the point where you copy the unpacked setup files.
2. Download and install Microsoft Debugging Tools for Windows. Choose the version of debugging tools matching your operating system version.
3. Find WinDbg in the start menu and launch it elevated.
4. In the WinDbg menu choose File -> Open Executable and open the unpacked Setup.exe. Say no to the question about saving workspace.
5. A new window will show up. There will be a box for entering commands at the bottom of the new window. This is the command line.
6. Write this into the command line and hit enter: bp ntdll!RtlGetNtProductType "as /x ReturnValue rcx; gu; ed ReturnValue 1; g". This will set up a breakpoint that will modify the return value of RtlGetNtProductType (anyone has a clean way of doing this for 32bit Windows?)
7. Write g on the command line and hit enter to resume the installer.
8. The installer will start – focus it’s window and click Next.
9. Go back to WinDbg. Hit Ctrl-Break. Type the command bc * to remove the breakpoint and after that g to resume the setup. Finish installing. Done.

If at some point in the future something breaks, don’t go back crying to me. I warned you.