Take the 2-minute tour ×
Information Security Stack Exchange is a question and answer site for Information security professionals. It's 100% free, no registration required.

I work in commercial telecoms and one part of our business is the leasing of computer equipment to call centers. If the customer for whatever reason gives us the equipment back (non-payment, out of business, downsizing) we lease out these same computers to the next customer.

Making sure the computers are ready to be shipped out again now falls under my responsibility, and I have been made aware that the previous method for resetting them was simply to log on, delete the contents of My Documents, and empty the recycle bin. I know this is in no way secure and what I now want to do is to combine the tasks of removing data properly, resetting the computer to a factory state, and installing a few specific programs into one operation.

Is it possible to create a custom Windows recovery/reset disk that will also install a select few programs AND change a number of settings? Where would I start?

share|improve this question

3 Answers 3

up vote 7 down vote accepted

What you describe is the worst possible practice possible apart from just handing it over. From a security standpoint it poses significant risks to both the previous and current parties.

The easiest way to reformat PCs is to use what is called a "golden image" this image is a windows image you:

  • keep up to date
  • only install the bare minimum of programs necessary

Next what you can do is setup a PXE server. Instead of using DVDs you just upload this disk to a central DHCP server and you hook the machine onto it. You then boot it into PXE mode and it will load the image from the network (if you use gigabit ethernet it can be a lot faster than a common DVD). The benefit of this is that you are basically can install a lot of machines concurrently without having to use DVDs. The nice part is that Windows also offers tools to completely automate this type of deployment including running post install scripts.

There is however a small catch, the disks also would need to be wiped clean before re-installing the windows image. Windows does offer this possibility using their Windows PE environment.

share|improve this answer
    
Thanks :) I'll do some research into setting up a PXE server. It's a small operation at the moment (hence why the previous person in charge of this didn't realise the risk) so I don't think replacing a hard drive every time is an option, at least for now. –  Adam Nov 5 '13 at 13:35
1  
If you need a fast turn around you could keep 1 or 2 'pre-loaded' hard drives and cycle them out with the machines coming in. That way you can get the machine out the door quickly and have time to securely wipe the incoming disk. –  Scott Helme Nov 5 '13 at 13:55

I'd implement either disk replacement, disk circulation, or secure disk wiping, depending on your resources/time constraints.

If possible, I'd take the large datacenter approach, and just remove and replace the disks, ideally destroying those that come out. Given that these will be fairly entry level machines, I'd say it would be easy to incorporate the cost of replacing a hard disk in the cost of lease, but whether your managers will agree with this is their call.

If that proves too much, I'd try to accumulate a surplus of disks, and remove disks, replacing them with securely erased disks in the meantime. You can be clearing off disks not in machines in readiness for the next batch of machines coming in. It's not the ideal, mainly because handling, removing, reinstalling etc on a regular basis will probably reduce the disk life span considerably.

Third option in my mind is to securely erase the disks in place when the machines come back in, which could be achieved with a USB setup to do this to whichever disk wiping standard you choose.

After you've wiped/replaced the drives, you can reinstall your base version of windows, setup however you wanted, probably using the method Lucas mentioned of a PXE server. I've used PXE servers to administrate networks, and it's a very satisfying way of performing reinstalls.

share|improve this answer

In addition to Lucas's answer above, you might want to start with prying the various EEPROMs off the motherboard, and reflash them with the latest firmware downloaded and verified from the manufacturers' website before soldering them back.

These steps would make sure there is no persistent malicious firmware present in the box before it is shipped to the next customer.

also, don't forget to dispose any existing SSD using fire or chemical methods since a data wipe might still fail depending on how the manufacturer implemented wear leveling on a particular SSD.

Heasman, J. 2007. Implementing and Detecting a PCI Rootkit

Sacco, AL, Ortega, A. 2009. Persistent BIOS Infection

share|improve this answer
    
You do not trust the secure erase command for SSDs? –  Hennes Nov 6 '13 at 13:49
    
@Hennes Altough I'd use secure erase on a SSD that I use on my gaming/casual browsing PC before selling/giving away it, I wouldn't trust it on customer PC's where a single leak could damage the company's reputation. I don't trust the closed firmwares in general., –  pwnd Nov 7 '13 at 12:00
    
I can not say that I disagree since I usually wipe disks (simple 3x overwrite) and then smash them with a hammer. However for consumer stuff I am happy with a secure erase. Then again, I know who ends up using my old hardware (family) and they are not capable of doing deep recovery tricks. –  Hennes Nov 7 '13 at 17:56

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.