SANS Digital Forensics and Incident Response Blog

SANS Digital Forensics and Incident Response Blog

Encrypted Disk Detector Version 2

Last year I covered the free Encrypted Disk Detector (EDD) tool and challenged the community to help crowdsource its development [link]. Thank you to all that took part in the experiment. Magnet Forensics announced today that Encrypted Disk Detector version 2 is available [get it here].

Survey Results


In addition to encouraging additional development of EDD, a side benefit of the project was to get an idea of the most popular disk encryption products being deployed. Figure 1 provides the survey results, with Checkpoint Full Disk Encryption, Symantec Endpoint Encryption, and Sophos (formerly Utimaco) Safeguard rounding out the top three. I think many of us could have guessed that big players like Symantec and Sophos would be near the top, but I was surprised to see products like BestCrypt and SecureDoc pull ahead of Credant Technologies (now owned by Dell).

Figure 1: EDD Survey Results



EDD Version 2


The EDD team took the feedback and implemented support for the top four survey results:
  • Checkpoint
  • GuardianEdge
  • SafeGuard
  • BestCrypt
Recall that the previous version of EDD identified full-disk and volume based encryption from Truecrypt, Bitlocker, and PGP. Interestingly, the newest additions do not have accessible disk signatures like the previous set. Thus EDD v2 now augments disk signature identification with process detection, which searches for running processes indicative of disk encryption products.

In addition to taking the survey, many respondents volunteered to be beta testers. Their help testing the update in real world environments was invaluable. Thank you! The following are a few screenshots from the final testing run:

Checkpoint Full Disk Encryption Detection


Checkpoint Status

Checkpoint Detection

Symantec Endpoint Encryption


Symantec Endpoint Encryption


Sophos Safeguard



Jetico Bestcrypt



The Future


In a zetabyte world, digital forensic triage becomes more important as our traditional "image everything" processes don't scale. Identifying encryption should be a critical step in live triage. With the current penetration of disk encryption products, we no longer have the luxury of assuming they don't exist, and our best opportunities for circumventing them exist while the system is running. Jad Saliba and his team were early proponents of triage and one of the first to release an encryption detection tool. Even with the latest updates, EDD does not purport to identify the universe of encryption products. However, it is an excellent start, and, with the v2 update, it now identifies the most popular products on the market. I am a big believer in the phrase "perfect is the enemy of good" and I would rather have a tool that can get me most of the information I need today rather than wait indefinitely for a "perfect" detection product. Hopefully this update to EDD will inspire additional innovation in this area. As mentioned by one survey respondent, the encryption detector of the future may need to go even further and detect device drivers and hooks to reduce false negatives. In the meantime, please thank the Magnet Forensics team next time you see them for this great update to EDD!

Chad Tilbury, GCFA, has spent over twelve years conducting computer crime investigations ranging from hacking to espionage to multi-million dollar fraud cases. He teachesFOR408 Windows Forensics and FOR508 Advanced Computer Forensic Analysis and Incident Responsefor the SANS Institute. Find him on Twitter @chadtilburyor at http://forensicmethods.com.

4 Comments

Posted April 25, 2013 at 12:12 PM | Permalink | Reply

Michael Dundas

I know that EDD detects Truecrypt volumes, but am I assuming it can only identify it as a Truecrypt Volume if it is already mounted? If the volume is unmounted, then I could see a program potentially detecting it as 'possibly encrypted' by calculating the entropy of the data being high, but how would it know it was in fact a Truecrypt volume? The articles indicate there is a 'signature', but if the Truecrypt volume is not mounted, then I fail to see how you would see a signature. I am not a cryptographer, but I have read through the details of how a Truecrypt volume is mounted and unencrypted and I don't see where you would find a signature?http://www.truecrypt.org/docs/encryption-scheme-mike

Posted April 26, 2013 at 11:21 PM | Permalink | Reply

Chad Tilbury

Hi Michael. EDD was built as a live response aid and hence focuses on mounted volumes (and disks) that exhibit signs of encryption. The idea being that if the system is currently running and the encrypted volume mounted, you have your best possible opportunity to collect data in that volume. EDD will not detect unmounted Truecrypt volumes. However, you may be interested in another free tool named TCHunt (written by 16 Systems) that was specifically created to identify un-mounted Truecrypt volumes.

Posted April 26, 2013 at 11:53 AM | Permalink | Reply

pixi

what is the influence of this tool for potential evidence changes?

Posted April 26, 2013 at 11:29 PM | Permalink | Reply

Chad Tilbury

Great question. Obviously any tool we run on a live system has some affect on that system. The expectation is that our live response tools will have as small of a footprint as possible. EDD is a small, targeted, non-GUI tool, so I would expect minimal impact. That being said, a good best practice is to benchmark your tools beforehand and document all actions taken during live response so you can later differentiate your actions from other system activity.

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