Tails from a Diskless Hyper-V

The Amnesic Incognito Live System (Tails) is open source privacy software. Tails “helps you to use the Internet anonymously almost anywhere you go and on any computer but leave no trace…”. This post explores how a Windows private cloud or data center might leverage Tails to harden defense in depth.

Tails is a Debian Linux .iso rootkit – er I mean boot image – configured to enable peer-to-peer encryption of e-mail messages and IM messages plus The Onion Router’s (Tor) anonymous SSL web browsing. Tor’s add-ins set [java]scripting and cookies off for all web sites by default, although the user can elect to allow scripts or cookies on a per site basis. The recommended way to use Tails is to burn a verified download of the .iso on to a write-once DVD and then use that DVD as the boot device to start the computer. Tails is mostly designed and configured to leave no trace in that scenario and to assure that once the verified image is laid down on a DVD it cannot be changed. 

One limitation of this preferred scenario is that you need to reboot the machine a couple of times each time you use Tails. Once to boot and once to remove the footprint left behind in memory.

Another limitation is that a DVD drive may not be readily available or accessible when needed. Tails developers suggest an almost as secure USB alternative to the DVD, but caution that an ability to surreptitiously modify the kernel is introduced. Tails also allows the user to manually configure local storage, opening a potential security hole. Local storage is needed, for example to load cryptographic keys for the secure OTR IM and PGP email messaging apps included for peer to peer privacy. Tails does automajically configure a piece of it’s memory as a RAMdisk allowing keys to be introduced without persistence in theory.

Virtualization too, I propose, can remove the reboot overhead, however the Tails documentation cautions against running Tails as a virtual machine (VM). “The main issue,” they say, “is if the host operating system is compromised with a software keylogger or other malware.” There simply is no facility for the VM to be sure no such spyware exists on the host. The usage I am suggesting below is the inverse of that trust model. Here we will use Tails to isolate the trusted host’s Windows domain from the Internet leveraging virtualization to help preserve the integrity of the trusted node. From a practical stand point, a better rule of thumb – though still in line with the cautious Tails statement on virtualization – may be to trust a virtual environment only to the extent you trust the underlying host environment(s) that support the virtual machine.

Nov 8, 2015 note – Unfortunately, the growing concerns that Tor is compromised are legitimate:

          https://invisibler.com/tor-compromised/

http://www.idigitaltimes.com/best-alternatives-tor-12-programs-use-nsa-hackers-compromised-tor-project-376976

Also, for virtualization other than Hyper-V see this information about Tails and virtual machine security at boum.org:

   https://tails.boum.org/doc/advanced_topics/virtualization/index.en.html 

A Windows Domain in a physically secured data center implies that the Domain and the data center Ops and admin staff are trusted. But when you open ports, especially 80/443, into that Domain that trust is at increased risk. Given Hyper-V administrator rights on a Windows 2012 Server – but not while logged in with administrative system rights on the server, using Tails from a virtual machine might just be a safer, more secure and self maintaining usability enhancement for a Windows-centric data center or private cloud. 

  • Tails can eliminate many requirements that expose the Windows Domain to the Internet. Internet risks are sandbox-ed on the Linux VM. The Linux instance has no rights or access in the Domain. The Domain has no rights or access to the Linux instance other than via Hyper-V Manager. Most interestingly, Tails boots to a Virtual Machine that has no disk space allocated (other than the RAM disk already mentioned).    
  • Tails will thwart most external traffic analysis efforts by competitors and adversaries. DPI sniffers and pen register access in the outside world will only expose the fact that you have traversed the Internet via SSL traffic to the Tor Network. SSL will prevent most snooping between the VM and the onion servers. No more than a handful of governments – and a few other cartels with adequate processing power – will even have the ability to backdoor through the Certificate Authority or brute force the SSL to actually see where you are going on the Internet.     
  • The Tails developer’s take care of the security updates and other maintenance. To upgrade or patch when used in the read-only diskless Hyper-V configuration, all you need do is download the latest image file. 

Some organizations may be resistant to this idea because Tails will also allow employees to privately and anonymously communicate with the outside world while at work. True enough, the broadcast pen register from a TOR packet will simply not provide adequate packet inspect-able forensic surveillance detail to know what data center employees are up to. That alone could put the kibosh on Tails from a Diskless Hyper-V.

Organizational fear of employees not withstanding, Tails in a Windows data-center presents a robust security profile with excellent usability for those times when the knowledge available on the Internet is urgently needed to help solve a problem or help understand a configuration. I would discourage efforts to configure a backdoor to monitor actual TAILS usage from the host simply because once that back door is opened anybody can walk through. Digital back doors swing both ways: better to put your monitoring energy into making sure there is no back door.

Tails is easy to deploy as a Hyper-V VM on Windows Server 2012 (or Windows 8 Pro with the Hyper-V client):

  • download and verify the file from https://tails.boum.org. No need to burn a DVD. Hyper-V will use the .iso file, although a DVD would work too if that is preferred and will undeniably help to assure the integrity of the image. A shared copy of the iso can be used across an environment. It is necessary to ensure that the VM host computer’s management account and the user account attempting to start the VM have full access to the file share and/or file system folder of the image . 
  • add a new Virtual Machine in Hyper-V Manager.TailsVM
  1. Give the VM 512MB of memory (dynamic works as well as static)
  2. Set the BIOS boot order to start with “CD”
  3. Set the .iso file – or physical DVD drive if that option is used – as the VM DVD Drive.
  4. Configure the VM with a virtual network adapter that can get to the Internet.

May 5, 2014 note – I had to enable MAC spoofing in HyperV for the Internet Network Adapter when I use the newly released tails version 1. The checkbox is located on the Advanced Features of the Network Adapter of the VM. You will not find the Advanced Features option when accessing the Virtual Switch.  It is a setting of the Network Adapter assigned to the tails VM. I suppose another option would be to remove the MAC address hardwired into tails’ “Auto eth0” but also would reduce your anonymity. It works this way but that is all the testing I did on it! Use the hardwired MAC if possible. 

  • Start the VM and specify a password for root when prompted. You will need to recreate the root password each time you start the VM in the diskless VM configuration. It can be a different password for each re-start. Your call though you should still use a strong password (e.g. suitable hardened to meet local password policies) and change it according to policy. The degree of protection of the local Domain from the Internet is dependent upon the security of this password. You never need to know that password again after you type it twice in succession and you don’t want anyone else to know it either… ever.
  • Use the Internet privately and anonymously from your shiny new diskless Virtual Machine.TailsVMDesktop

Iceweasel can browse the Internet just fine in the diskless configuration. Using PGP or OTR, however, both require persisted certificates. That requires disk storage. Instant Messenger and pop email using the tools in Tails won’t happen unless persistent certificates are available. There are probably a number of ways certificate availability can be realized, e.g., RamDisk, network, fob, etc.

A Hyper-V Administrator cannot be prevented from configuring storage inside the Virtual Machine if storage is available to the Hyper-V. Hint: A Hyper-V Administrator can be prevented from configuring storage inside the Virtual Machine if no storage is available to the Hyper-V Administrator.

Not a total solution, but gives a very clean ability to jump on the Internet without exposing the domain to the Internet when needed.

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2 Responses to Tails from a Diskless Hyper-V

  1. Sil says:

    Not working on Win 10 / Hyper-V, even with the secure boot option unchecked in the VM configuration.
    Hyper-V complains that
    No UEFI-compatible filesystem is found.
    Do you know of a workaround?

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