Dr. Phil Polstra discussing Equimelt

Lee Neubecker: I’m here with Dr. Phil Polstra and we’re talking a little bit today about some research I had done that I reached out to him about involving root certificates that I found on a Windows 10 computer that did not appear to be on Microsoft’s list of trusted certificates. Specifically, what I had done, is I took Microsoft’s January 2018 list of trusted root certificates and manually compared that list against the certificates that existed in my fully updated Windows 10 Pro machine.

I identified four certificates that were not in Microsoft’s trusted root list.

Now, what’s concerning to me is, first of all, some of the entities involved are specific entities that Google Chrome is now revoking and blocking the trust on because they’ve seen impersonations by some of these entities for certifications. Additionally, I was very concerned about the Equifax root certificate.

I don’t know about you but given what Equifax has done and the breaches that they’ve suffered, I just can’t imagine that their private key has been protected. I wanted to talk to you a little bit more about that. A number of people in the IT community have examined their certificates and these certificates are widely distributed – not just limited to your computer or the computers I’ve had.

Fortunately, we’ve learned how to disable those certs, but they’re still out there, pretty far and wide. What are your thoughts about the potential risks associated with these certificates, and how can they be used by a nefarious actor to compromise a target.

Dr. Phil Polstra: Well, there’s no reason for them to be there, so there’s no harm in getting rid of them, number one. Number two, they are some pretty old certificates, and they’re using older, deprecated SHA1 algorithm and things like that for signing. So there certainly is enough potential for someone to use those old certificates as a way of infiltrating a system that I would certainly recommend getting rid of those.

Neubecker: I have a question for you – there’s been widespread discussion online, some of which says well, even though it’s a SHA1 certificate, it doesn’t matter because it’s a root and a self-root of trust. But cryptographically speaking, if you had a known private-public key pair of an intermediate certificate signed by that Equifax root, with that information plus the public certificate of Equifax root, you would have three of the four variables.

Is it mathematically possible if you had an intermediate key pair, private-public, plus a public key, to crack the Equifax root private key?

Dr. Polstra: It certainly becomes more doable because you have a lot more information now and again you’re using the older algorithms that have been deprecated, so I would say it would be much more likely that you can pull it off.

Neubecker: How likely is it that nation-states like China have that private key?

Dr. Polstra: If you have those kinds of resources, then I would say very likely. It’s kind of like a hard drive, if I take a hard drive and overwrite 40 times, the average person is not going to recover that information, but a government could. It’s all a matter of how badly someone wants it, and if they have enough resources they’re going to get it.

Neubecker: Given the likelihood that the private key sometime in the last 20 years was compromised either by China through brute-force attacks or by Equifax just not holding on to that private key as they sold it to one company and then another, what would you recommend companies do if they discover these keys on their computers?

Dr. Polstra: I’d say disable them, remove them.

Neubecker: Some have said that you need that for legacy hardware, that it needs to be there for legacy hardware.

Dr. Polstra: I don’t believe that’s true, and I’ll say this – if something suddenly stopped working, I’d be very surprised.

Neubecker: It would make sense that if you don’t trust it, if you find a classic device you need to play one of your favorite video game and it was signed by an Equifax driver, you can one-off choose to trust it for that instance, but I just assume not use anything.

Dr. Polstra: I wouldn’t trust it by default.

Neubecker: Why would a laptop that you bought in the last year running on Windows 10 Pro, the business edition of Windows, why would it need the Equifax root certificate?

Dr. Polstra: I guess maybe you shouldn’t be playing those games on your business computer anyways.

Neubecker: I’m still struggling because after I published this research online, the people who’ve attacked me and tried to discredit the research, they’ve been more focused on not the root of the issue which is do you trust the private key is protected, they’ve been focusing on can you demonstrate the ability to perform a certain type of cryptographic attack.

But you don’t even need the math to be crack-able if the private key is compromised, right?

Dr. Polstra: Exactly.

Neubecker: What happens – your root certificates in your trusted root, what can they do on a computer?

Dr. Polstra: Well really, if you got the trusted root certificate, you could install most anything.

Neubecker: So, you could essentially own the computer?

Dr. Polstra: Exactly, and it’s not going to set off any alarms because it’s trusted.

Neubecker: But could a trusted root certificate, if it’s there, could it make an alternate version of antivirus that doesn’t really detect?

Dr. Polstra: I would say that’s certainly possible.

Neubecker: These are things that, unfortunately, people aren’t responding to and there’s still an effort by many to suppress the information because, if you were to remove these rogue certificates, as I call them, then it would compromise some of the cyber tools out there that might rely on weak crypto.

Dr. Polstra: But why are they relying on weak crypto?

Neubecker: Exactly, in my opinion, there should be a government-public initiative to replace all private key and public key infrastructure so that everything in your trusted root should be, ideally, 2018 or later. Might take a couple of years to get there but we should be rekeying. I’m still troubled by why some of our government agencies are still using keys that were signed by government agencies prior to compromises of the CIA, NSA.

You’d think that if you had a house break in, you’d change the locks. But we still haven’t changed the locks.

Dr. Polstra: And at a minimum you’d get better locks, more modern locks.

Neubecker: I read one advisory from the NSA on the Information Assurance Division website, IAD.gov, and it advised that other agencies look out for weak certificates that were on routers and networking devices, that it could be indicative of an advanced persistent threat or compromise. More recently, in February, they disclosed that there were Cisco vulnerabilities on various Cisco ASA routers that are widely used by the government but there are no patches for as of the publication date.

You have to fully update it, but there still isn’t a complete fix. The state of cyber security is a little bit concerning, but there are things that should be done. It comes down to stop using weak crypto, and make sure you trust what’s in your root, and make sure all the hardware on board, those equipment makers need to use stronger cryptography to validate the drivers and software, otherwise the hardware is going to get compromised and these threats will keep re-emerging.

Dr. Polstra: Exactly.

Neubecker: What would you say that hardware makers should be doing today to make the world more cyber secure.

Dr. Polstra: That’s a great question – certainly some of the things you’ve mentioned. Let’s use some better crypto, let’s use modern algorithms out there, and let’s have people signing their hardware, let’s have people controlling that so we have a little bit better of a grasp on whether or not things have been modified – I think that would go a long way, and would be a good place to start.

Neubecker: Thank you for being on the show and I’m looking forward to the conference this weekend.

Dr. Polstra: Sounds great, I’m looking forward to it as well.

Dr. Phil Polstra is an Associate Professor in the department of Math Computer Science and Statistics specializing in digital forensics and computer security at Bloomsburg University in Bloomsburg, Pennsylvania.  He is the noted author of Windows Forensics, Linux Forensics, Hacking and Penetration Testing with Low Power Devices, and hundreds of instructional videos. Hardware hacker and security professional. International speaker.

Dr. Phil’s blog can be found at http://ppolstra.blogspot.com/