In this article we will be looking at how easy it is to bypass authentication và reset the administrator password on a Windows server 2008 R2 installation. This technique requires us to have physical access khổng lồ the machine that is running the Windows server or have access to lớn the management interface of the hypervisor when Windows hệ thống 2008 R2 is running virtualized. This is not a great ‘hacking’ technique that can be used lớn pwn all Windows installations but it is more a sysadmins last resort trick when nothing else works on a forgotten password. & in some other situations it is definitely useful and comes in handy when you need it. Especially at the point when you’ve compromised the administration panel of the hypervisor software. This kind of access allows you to control the virtual machines as if you had physical access khổng lồ it, including the ability khổng lồ use boot disk and modify system files. Alternatively you can apply this technique when have some kind of physical access khổng lồ a host.Bạn đã xem: Reset or remove any windows password with hiren's bootcd

A couple months ago I was conducting a penetration kiểm tra on a staged Windows environment that was running on a VMware hypervisor. The environment contained a domain controller and 3 application servers that were running Windows server 2008 R2. Other then the Windows machines I also encountered a few Linux based network & back-up devices. As it was not very hard khổng lồ compromise the machines on this network I was able khổng lồ access the VMware vSphere administration panel as administrator in a very early stage of the penetration test. This access level allowed me to lớn reset the administrator password using a boot CD & finally login lớn the Windows Server with administrator privileges. In the follow sections I will explain how I did this & how you can secure your Windows installations from applying this technique.

Resetting the administrator password on Windows vps 2008 R2

The starting point of this tutorial is a machine with Windows server 2008 R2 Enterprise that has been booted with a boot CD. In this example we’ve used the Hiren boot CD (HBCD) but you can use any alternative boot CD as well, including a Windows installation disk. After booting the system from the boot CD navigate lớn the following directory of the drive that contains the Windows server 2008 R2 installation:

/Windows/System32

In this directory you will find an executable tệp tin named ‘Utilman.exe’. Utilman is a small utility that is used lớn configure accessibility options such as the magnifier & the on-screen keyboard. What’s so special about Utilman.exe is that we are able to lớn execute this program before logging in the system. We can do this by clicking the small ‘accessibility’ button in the bottom left corner of the Windows logon menu:


*

The ‘accessibility’ button to lớn launch Utilman.exe displayed at the left.

Now that we have access to the /Windows/System32 directory we can swap out the Utilman.exe program with the cmd.exe program. When we swap out these applications we can start cmd.exe with system privileges instead of Utilman.exe when pressing the accessibility button in the logon screen. From this point we are able to reset the administrator password and use it to login.

First we will rename the Utilman.exe program khổng lồ Utilman.exe.old as following:


*

*

Now that we’ve swapped Utilman.exe with cmd.exe we only have khổng lồ reboot the machine into Windows và click the accessibility button on the login screen. As expected this will launch a command line instead of the accessibility options:


*

*

Windows server 2008 R2 Enterprise signing in with the new administrator credentials.

Lessons learned

In this article we’ve seen how easy it is lớn get administrator access to a Windows vps 2008 R2 Enterprise host after we’ve compromised the hypervisor. Just the fact that we were able khổng lồ boot the machine with a boot CD allowing us lớn tamper with data on the hard drive is a serious security issue with serious consequences. There are several ways khổng lồ prevent and mitigate these kind of attacks. One of them is khổng lồ secure the BIOS with a password so that an attacker cannot change the boot options for the machine, thus unable lớn boot from the boot CD. A more effective way would be khổng lồ apply full disk encryption which encrypts all the data on the disk preventing the attacker from tampering with it.

I hope you’ve found this small tutorial useful in some way. If you’re looking lớn try this technique or to practice penetration testing techniques on Windows vps 2008 machines, I can recommend you khổng lồ install Metasploitable 3 which is based on Windows server 2008.