Entries Tagged "computer security"

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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.

Posted on February 10, 2014 at 6:57 AM • View Comments

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.

Posted on November 7, 2013 at 7:06 AM • View Comments

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.

Other discussions.

EDITED TO ADD: More discussions.

EDITED TO ADD (11/14): A claimed debunking

Posted on November 4, 2013 at 6:15 AM • View Comments

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:

  1. 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.)

  2. 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.)

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

Posted on October 11, 2013 at 6:45 AM • View Comments

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:

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.

Posted on September 15, 2013 at 8:11 AM • View Comments

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.

Posted on August 12, 2013 at 2:33 PM • View Comments

More on Feudal Security

Facebook regularly abuses the privacy of its users. Google has stopped supporting its popular RSS feeder. Apple prohibits all iPhone apps that are political or sexual. Microsoft might be cooperating with some governments to spy on Skype calls, but we don’t know which ones. Both Twitter and LinkedIn have recently suffered security breaches that affected the data of hundreds of thousands of their users.

If you’ve started to think of yourself as a hapless peasant in a Game of Thrones power struggle, you’re more right than you may realize. These are not traditional companies, and we are not traditional customers. These are feudal lords, and we are their vassals, peasants, and serfs.

Power has shifted in IT, in favor of both cloud-service providers and closed-platform vendors. This power shift affects many things, and it profoundly affects security.

Traditionally, computer security was the user’s responsibility. Users purchased their own antivirus software and firewalls, and any breaches were blamed on their inattentiveness. It’s kind of a crazy business model. Normally we expect the products and services we buy to be safe and secure, but in IT we tolerated lousy products and supported an enormous aftermarket for security.

Now that the IT industry has matured, we expect more security “out of the box.” This has become possible largely because of two technology trends: cloud computing and vendor-controlled platforms. The first means that most of our data resides on other networks: Google Docs, Salesforce.com, Facebook, Gmail. The second means that our new Internet devices are both closed and controlled by the vendors, giving us limited configuration control: iPhones, ChromeBooks, Kindles, BlackBerry PDAs. Meanwhile, our relationship with IT has changed. We used to use our computers to do things. We now use our vendor-controlled computing devices to go places. All of these places are owned by someone.

The new security model is that someone else takes care of it—without telling us any of the details. I have no control over the security of my Gmail or my photos on Flickr. I can’t demand greater security for my presentations on Prezi or my task list on Trello, no matter how confidential they are. I can’t audit any of these cloud services. I can’t delete cookies on my iPad or ensure that files are securely erased. Updates on my Kindle happen automatically, without my knowledge or consent. I have so little visibility into the security of Facebook that I have no idea what operating system they’re using.

There are a lot of good reasons why we’re all flocking to these cloud services and vendor-controlled platforms. The benefits are enormous, from cost to convenience to reliability to security itself. But it is inherently a feudal relationship. We cede control of our data and computing platforms to these companies and trust that they will treat us well and protect us from harm. And if we pledge complete allegiance to them—if we let them control our email and calendar and address book and photos and everything—we get even more benefits. We become their vassals; or, on a bad day, their serfs.

There are a lot of feudal lords out there. Google and Apple are the obvious ones, but Microsoft is trying to control both user data and the end-user platform as well. Facebook is another lord, controlling much of the socializing we do on the Internet. Other feudal lords are smaller and more specialized—Amazon, Yahoo, Verizon, and so on—but the model is the same.

To be sure, feudal security has its advantages. These companies are much better at security than the average user. Automatic backup has saved a lot of data after hardware failures, user mistakes, and malware infections. Automatic updates have increased security dramatically. This is also true for small organizations; they are more secure than they would be if they tried to do it themselves. For large corporations with dedicated IT security departments, the benefits are less clear. Sure, even large companies outsource critical functions like tax preparation and cleaning services, but large companies have specific requirements for security, data retention, audit, and so on—and that’s just not possible with most of these feudal lords.

Feudal security also has its risks. Vendors can, and do, make security mistakes affecting hundreds of thousands of people. Vendors can lock people into relationships, making it hard for them to take their data and leave. Vendors can act arbitrarily, against our interests; Facebook regularly does this when it changes peoples’ defaults, implements new features, or modifies its privacy policy. Many vendors give our data to the government without notice, consent, or a warrant; almost all sell it for profit. This isn’t surprising, really; companies should be expected to act in their own self-interest and not in their users’ best interest.

The feudal relationship is inherently based on power. In Medieval Europe, people would pledge their allegiance to a feudal lord in exchange for that lord’s protection. This arrangement changed as the lords realized that they had all the power and could do whatever they wanted. Vassals were used and abused; peasants were tied to their land and became serfs.

It’s the Internet lords’ popularity and ubiquity that enable them to profit; laws and government relationships make it easier for them to hold onto power. These lords are vying with each other for profits and power. By spending time on their sites and giving them our personal information—whether through search queries, e-mails, status updates, likes, or simply our behavioral characteristics—we are providing the raw material for that struggle. In this way we are like serfs, toiling the land for our feudal lords. If you don’t believe me, try to take your data with you when you leave Facebook. And when war breaks out among the giants, we become collateral damage.

So how do we survive? Increasingly, we have little alternative but to trust someone, so we need to decide who we trust—and who we don’t—and then act accordingly. This isn’t easy; our feudal lords go out of their way not to be transparent about their actions, their security, or much of anything. Use whatever power you have—as individuals, none; as large corporations, more—to negotiate with your lords. And, finally, don’t be extreme in any way: politically, socially, culturally. Yes, you can be shut down without recourse, but it’s usually those on the edges that are affected. Not much solace, I agree, but it’s something.

On the policy side, we have an action plan. In the short term, we need to keep circumvention—the ability to modify our hardware, software, and data files—legal and preserve net neutrality. Both of these things limit how much the lords can take advantage of us, and they increase the possibility that the market will force them to be more benevolent. The last thing we want is the government—that’s us—spending resources to enforce one particular business model over another and stifling competition.

In the longer term, we all need to work to reduce the power imbalance. Medieval feudalism evolved into a more balanced relationship in which lords had responsibilities as well as rights. Today’s Internet feudalism is both ad hoc and one-sided. We have no choice but to trust the lords, but we receive very few assurances in return. The lords have a lot of rights, but few responsibilities or limits. We need to balance this relationship, and government intervention is the only way we’re going to get it. In medieval Europe, the rise of the centralized state and the rule of law provided the stability that feudalism lacked. The Magna Carta first forced responsibilities on governments and put humans on the long road toward government by the people and for the people.

We need a similar process to rein in our Internet lords, and it’s not something that market forces are likely to provide. The very definition of power is changing, and the issues are far bigger than the Internet and our relationships with our IT providers.

This essay originally appeared on the Harvard Business Review website. It is an update of this earlier essay on the same topic. “Feudal security” is a metaphor I have been using a lot recently; I wrote this essay without rereading my previous essay.

EDITED TO ADD (6/13): There is another way the feudal metaphor applies to the Internet. There is no commons; every part of the Internet is owned by someone. This article explores that aspect of the metaphor.

Posted on June 13, 2013 at 11:34 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.