Entries Tagged "computer security"
Page 8 of 33
NSA/GCHQ Accused of Hacking Belgian Cryptographer
There has been a lot of news about Belgian cryptographer Jean-Jacques Quisquater having his computer hacked, and whether the NSA or GCHQ is to blame. There have been a lot of assumptions and hyperbole, mostly related to the GCHQ attack against the Belgian telecom operator Belgacom.
I’m skeptical. Not about the attack, but about the NSA’s or GCHQ’s involvement. I don’t think there’s a lot of operational value in most academic cryptographic research, and Quisquater wasn’t involved in practical cryptanalysis of operational ciphers. I wouldn’t put it past a less-clued nation-state to spy on academic cryptographers, but it’s likelier this is a more conventional criminal attack. But who knows? Weirder things have happened.
New Security Risks for Windows XP Systems
Microsoft is trying to stop supporting Windows XP. The problem is that a majority of ATMs still use that OS. And once Microsoft stops issuing security updates to XP, those machines will become increasingly vulnerable.
Although I have to ask the question: how many of those ATMs have been keeping up with their patches so far?
We have far to go with our security of embedded systems.
Risk-Based Authentication
I like this idea of giving each individual login attempt a risk score, based on the characteristics of the attempt:
The risk score estimates the risk associated with a log-in attempt based on a user’s typical log-in and usage profile, taking into account their device and geographic location, the system they’re trying to access, the time of day they typically log in, their device’s IP address, and even their typing speed. An employee logging into a CRM system using the same laptop, at roughly the same time of day, from the same location and IP address will have a low risk score. By contrast, an attempt to access a finance system from a tablet at night in Bali could potentially yield an elevated risk score.
Risk thresholds for individual systems are established based on the sensitivity of the information they store and the impact if the system were breached. Systems housing confidential financial data, for example, will have a low risk threshold.
If the risk score for a user’s access attempt exceeds the system’s risk threshold, authentication controls are automatically elevated, and the user may be required to provide a higher level of authentication, such as a PIN or token. If the risk score is too high, it may be rejected outright.
badBIOS
Good story of badBIOS, a really nasty piece of malware. The weirdest part is how it uses ultrasonic sound to jump air gaps.
Ruiu said he arrived at the theory about badBIOS’s high-frequency networking capability after observing encrypted data packets being sent to and from an infected machine that had no obvious network connection with—but was in close proximity to—another badBIOS-infected computer. The packets were transmitted even when one of the machines had its Wi-Fi and Bluetooth cards removed. Ruiu also disconnected the machine’s power cord to rule out the possibility it was receiving signals over the electrical connection. Even then, forensic tools showed the packets continued to flow over the airgapped machine. Then, when Ruiu removed internal speaker and microphone connected to the airgapped machine, the packets suddenly stopped.
With the speakers and mic intact, Ruiu said, the isolated computer seemed to be using the high-frequency connection to maintain the integrity of the badBIOS infection as he worked to dismantle software components the malware relied on.
“The airgapped machine is acting like it’s connected to the Internet,” he said. “Most of the problems we were having is we were slightly disabling bits of the components of the system. It would not let us disable some things. Things kept getting fixed automatically as soon as we tried to break them. It was weird.”
I’m not sure what to make of this. When I first read it, I thought it was a hoax. But enough others are taking it seriously that I think it’s a real story. I don’t know whether the facts are real, and I haven’t seen anything about what this malware actually does.
EDITED TO ADD: More discussions.
EDITED TO ADD (11/14): A claimed debunking
Air Gaps
Since I started working with Snowden’s documents, I have been using a number of tools to try to stay secure from the NSA. The advice I shared included using Tor, preferring certain cryptography over others, and using public-domain encryption wherever possible.
I also recommended using an air gap, which physically isolates a computer or local network of computers from the Internet. (The name comes from the literal gap of air between the computer and the Internet; the word predates wireless networks.)
But this is more complicated than it sounds, and requires explanation.
Since we know that computers connected to the Internet are vulnerable to outside hacking, an air gap should protect against those attacks. There are a lot of systems that use—or should use—air gaps: classified military networks, nuclear power plant controls, medical equipment, avionics, and so on.
Osama Bin Laden used one. I hope human rights organizations in repressive countries are doing the same.
Air gaps might be conceptually simple, but they’re hard to maintain in practice. The truth is that nobody wants a computer that never receives files from the Internet and never sends files out into the Internet. What they want is a computer that’s not directly connected to the Internet, albeit with some secure way of moving files on and off.
But every time a file moves back or forth, there’s the potential for attack.
And air gaps have been breached. Stuxnet was a US and Israeli military-grade piece of malware that attacked the Natanz nuclear plant in Iran. It successfully jumped the air gap and penetrated the Natanz network. Another piece of malware named agent.btz, probably Chinese in origin, successfully jumped the air gap protecting US military networks.
These attacks work by exploiting security vulnerabilities in the removable media used to transfer files on and off the air-gapped computers.
Since working with Snowden’s NSA files, I have tried to maintain a single air-gapped computer. It turned out to be harder than I expected, and I have ten rules for anyone trying to do the same:
- When you set up your computer, connect it to the Internet as little as possible. It’s impossible to completely avoid connecting the computer to the Internet, but try to configure it all at once and as anonymously as possible. I purchased my computer off-the-shelf in a big box store, then went to a friend’s network and downloaded everything I needed in a single session. (The ultra-paranoid way to do this is to buy two identical computers, configure one using the above method, upload the results to a cloud-based anti-virus checker, and transfer the results of that to the air gap machine using a one-way process.)
-
Install the minimum software set you need to do your job, and disable all operating system services that you won’t need. The less software you install, the less an attacker has available to exploit. I downloaded and installed OpenOffice, a PDF reader, a text editor, TrueCrypt, and BleachBit. That’s all. (No, I don’t have any inside knowledge about TrueCrypt, and there’s a lot about it that makes me suspicious. But for Windows full-disk encryption it’s that, Microsoft’s BitLocker, or Symantec’s PGPDisk—and I am more worried about large US corporations being pressured by the NSA than I am about TrueCrypt.)
-
Once you have your computer configured, never directly connect it to the Internet again. Consider physically disabling the wireless capability, so it doesn’t get turned on by accident.
-
If you need to install new software, download it anonymously from a random network, put it on some removable media, and then manually transfer it to the air-gapped computer. This is by no means perfect, but it’s an attempt to make it harder for the attacker to target your computer.
-
Turn off all autorun features. This should be standard practice for all the computers you own, but it’s especially important for an air-gapped computer. Agent.btz used autorun to infect US military computers.
-
Minimize the amount of executable code you move onto the air-gapped computer. Text files are best. Microsoft Office files and PDFs are more dangerous, since they might have embedded macros. Turn off all macro capabilities you can on the air-gapped computer. Don’t worry too much about patching your system; in general, the risk of the executable code is worse than the risk of not having your patches up to date. You’re not on the Internet, after all.
-
Only use trusted media to move files on and off air-gapped computers. A USB stick you purchase from a store is safer than one given to you by someone you don’t know—or one you find in a parking lot.
-
For file transfer, a writable optical disk (CD or DVD) is safer than a USB stick. Malware can silently write data to a USB stick, but it can’t spin the CD-R up to 1000 rpm without your noticing. This means that the malware can only write to the disk when you write to the disk. You can also verify how much data has been written to the CD by physically checking the back of it. If you’ve only written one file, but it looks like three-quarters of the CD was burned, you have a problem. Note: the first company to market a USB stick with a light that indicates a write operation—not read or write; I’ve got one of those—wins a prize.
-
When moving files on and off your air-gapped computer, use the absolute smallest storage device you can. And fill up the entire device with random files. If an air-gapped computer is compromised, the malware is going to try to sneak data off it using that media. While malware can easily hide stolen files from you, it can’t break the laws of physics. So if you use a tiny transfer device, it can only steal a very small amount of data at a time. If you use a large device, it can take that much more. Business-card-sized mini-CDs can have capacity as low as 30 MB. I still see 1-GB USB sticks for sale.
-
Consider encrypting everything you move on and off the air-gapped computer. Sometimes you’ll be moving public files and it won’t matter, but sometimes you won’t be, and it will. And if you’re using optical media, those disks will be impossible to erase. Strong encryption solves these problems. And don’t forget to encrypt the computer as well; whole-disk encryption is the best.
One thing I didn’t do, although it’s worth considering, is use a stateless operating system like Tails. You can configure Tails with a persistent volume to save your data, but no operating system changes are ever saved. Booting Tails from a read-only DVD—you can keep your data on an encrypted USB stick—is even more secure. Of course, this is not foolproof, but it greatly reduces the potential avenues for attack.
Yes, all this is advice for the paranoid. And it’s probably impossible to enforce for any network more complicated than a single computer with a single user. But if you’re thinking about setting up an air-gapped computer, you already believe that some very powerful attackers are after you personally. If you’re going to use an air gap, use it properly.
Of course you can take things further. I have met people who have physically removed the camera, microphone, and wireless capability altogether. But that’s too much paranoia for me right now.
This essay previously appeared on Wired.com.
EDITED TO ADD: Yes, I am ignoring TEMPEST attacks. I am also ignoring black bag attacks against my home.
How to Remain Secure Against the NSA
Now that we have enough details about how the NSA eavesdrops on the Internet, including today’s disclosures of the NSA’s deliberate weakening of cryptographic systems, we can finally start to figure out how to protect ourselves.
For the past two weeks, I have been working with the Guardian on NSA stories, and have read hundreds of top-secret NSA documents provided by whistleblower Edward Snowden. I wasn’t part of today’s story—it was in process well before I showed up—but everything I read confirms what the Guardian is reporting.
At this point, I feel I can provide some advice for keeping secure against such an adversary.
The primary way the NSA eavesdrops on Internet communications is in the network. That’s where their capabilities best scale. They have invested in enormous programs to automatically collect and analyze network traffic. Anything that requires them to attack individual endpoint computers is significantly more costly and risky for them, and they will do those things carefully and sparingly.
Leveraging its secret agreements with telecommunications companies—all the US and UK ones, and many other “partners” around the world—the NSA gets access to the communications trunks that move Internet traffic. In cases where it doesn’t have that sort of friendly access, it does its best to surreptitiously monitor communications channels: tapping undersea cables, intercepting satellite communications, and so on.
That’s an enormous amount of data, and the NSA has equivalently enormous capabilities to quickly sift through it all, looking for interesting traffic. “Interesting” can be defined in many ways: by the source, the destination, the content, the individuals involved, and so on. This data is funneled into the vast NSA system for future analysis.
The NSA collects much more metadata about Internet traffic: who is talking to whom, when, how much, and by what mode of communication. Metadata is a lot easier to store and analyze than content. It can be extremely personal to the individual, and is enormously valuable intelligence.
The Systems Intelligence Directorate is in charge of data collection, and the resources it devotes to this is staggering. I read status report after status report about these programs, discussing capabilities, operational details, planned upgrades, and so on. Each individual problem—recovering electronic signals from fiber, keeping up with the terabyte streams as they go by, filtering out the interesting stuff—has its own group dedicated to solving it. Its reach is global.
The NSA also attacks network devices directly: routers, switches, firewalls, etc. Most of these devices have surveillance capabilities already built in; the trick is to surreptitiously turn them on. This is an especially fruitful avenue of attack; routers are updated less frequently, tend not to have security software installed on them, and are generally ignored as a vulnerability.
The NSA also devotes considerable resources to attacking endpoint computers. This kind of thing is done by its TAO—Tailored Access Operations—group. TAO has a menu of exploits it can serve up against your computer—whether you’re running Windows, Mac OS, Linux, iOS, or something else—and a variety of tricks to get them on to your computer. Your anti-virus software won’t detect them, and you’d have trouble finding them even if you knew where to look. These are hacker tools designed by hackers with an essentially unlimited budget. What I took away from reading the Snowden documents was that if the NSA wants in to your computer, it’s in. Period.
The NSA deals with any encrypted data it encounters more by subverting the underlying cryptography than by leveraging any secret mathematical breakthroughs. First, there’s a lot of bad cryptography out there. If it finds an Internet connection protected by MS-CHAP, for example, that’s easy to break and recover the key. It exploits poorly chosen user passwords, using the same dictionary attacks hackers use in the unclassified world.
As was revealed today, the NSA also works with security product vendors to ensure that commercial encryption products are broken in secret ways that only it knows about. We know this has happened historically: CryptoAG and Lotus Notes are the most public examples, and there is evidence of a back door in Windows. A few people have told me some recent stories about their experiences, and I plan to write about them soon. Basically, the NSA asks companies to subtly change their products in undetectable ways: making the random number generator less random, leaking the key somehow, adding a common exponent to a public-key exchange protocol, and so on. If the back door is discovered, it’s explained away as a mistake. And as we now know, the NSA has enjoyed enormous success from this program.
TAO also hacks into computers to recover long-term keys. So if you’re running a VPN that uses a complex shared secret to protect your data and the NSA decides it cares, it might try to steal that secret. This kind of thing is only done against high-value targets.
How do you communicate securely against such an adversary? Snowden said it in an online Q&A soon after he made his first document public: “Encryption works. Properly implemented strong crypto systems are one of the few things that you can rely on.”
I believe this is true, despite today’s revelations and tantalizing hints of “groundbreaking cryptanalytic capabilities” made by James Clapper, the director of national intelligence in another top-secret document. Those capabilities involve deliberately weakening the cryptography.
Snowden’s follow-on sentence is equally important: “Unfortunately, endpoint security is so terrifically weak that NSA can frequently find ways around it.”
Endpoint means the software you’re using, the computer you’re using it on, and the local network you’re using it in. If the NSA can modify the encryption algorithm or drop a Trojan on your computer, all the cryptography in the world doesn’t matter at all. If you want to remain secure against the NSA, you need to do your best to ensure that the encryption can operate unimpeded.
With all this in mind, I have five pieces of advice:
- Hide in the network. Implement hidden services. Use Tor to anonymize yourself. Yes, the NSA targets Tor users, but it’s work for them. The less obvious you are, the safer you are.
- Encrypt your communications. Use TLS. Use IPsec. Again, while it’s true that the NSA targets encrypted connections—and it may have explicit exploits against these protocols—you’re much better protected than if you communicate in the clear.
- Assume that while your computer can be compromised, it would take work and risk on the part of the NSA—so it probably isn’t. If you have something really important, use an air gap. Since I started working with the Snowden documents, I bought a new computer that has never been connected to the Internet. If I want to transfer a file, I encrypt the file on the secure computer and walk it over to my Internet computer, using a USB stick. To decrypt something, I reverse the process. This might not be bulletproof, but it’s pretty good.
- Be suspicious of commercial encryption software, especially from large vendors. My guess is that most encryption products from large US companies have NSA-friendly back doors, and many foreign ones probably do as well. It’s prudent to assume that foreign products also have foreign-installed backdoors. Closed-source software is easier for the NSA to backdoor than open-source software. Systems relying on master secrets are vulnerable to the NSA, through either legal or more clandestine means.
- Try to use public-domain encryption that has to be compatible with other implementations. For example, it’s harder for the NSA to backdoor TLS than BitLocker, because any vendor’s TLS has to be compatible with every other vendor’s TLS, while BitLocker only has to be compatible with itself, giving the NSA a lot more freedom to make changes. And because BitLocker is proprietary, it’s far less likely those changes will be discovered. Prefer symmetric cryptography over public-key cryptography. Prefer conventional discrete-log-based systems over elliptic-curve systems; the latter have constants that the NSA influences when they can.
Since I started working with Snowden’s documents, I have been using GPG, Silent Circle, Tails, OTR, TrueCrypt, BleachBit, and a few other things I’m not going to write about. There’s an undocumented encryption feature in my Password Safe program from the command line; I’ve been using that as well.
I understand that most of this is impossible for the typical Internet user. Even I don’t use all these tools for most everything I am working on. And I’m still primarily on Windows, unfortunately. Linux would be safer.
The NSA has turned the fabric of the Internet into a vast surveillance platform, but they are not magical. They’re limited by the same economic realities as the rest of us, and our best defense is to make surveillance of us as expensive as possible.
Trust the math. Encryption is your friend. Use it well, and do your best to ensure that nothing can compromise it. That’s how you can remain secure even in the face of the NSA.
This essay previously appeared in the Guardian.
EDITED TO ADD: Reddit thread.
Someone somewhere commented that the NSA’s “groundbreaking cryptanalytic capabilities” could include a practical attack on RC4. I don’t know one way or the other, but that’s a good speculation.
NSA Increasing Security by Firing 90% of Its Sysadmins
General Keith Alexander thinks he can improve security by automating sysadmin duties such that 90% of them can be fired:
Using technology to automate much of the work now done by employees and contractors would make the NSA’s networks “more defensible and more secure,” as well as faster, he said at the conference, in which he did not mention Snowden by name.
Does anyone know a sysadmin anywhere who believes it’s possible to automate 90% of his job? Or who thinks any such automation will actually improve security?
He’s stuck. Computerized systems require trusted people to administer them. And any agency with all that computing power is going to need thousands of sysadmins. Some of them are going to be whistleblowers.
Leaking secret information is the civil disobedience of our age. Alexander has to get used to it.
MAD in Cyberspace
Rod Beckstrom gives a talk (video and transcript) about “Mutually Assured Destruction,” “Mutually Assured Disruption,” and “Mutually Assured Dependence.”
Spear Phishing Attack Against the Financial Times
Interesting story with a lot of details.
Sidebar photo of Bruce Schneier by Joe MacInnis.