Blog: June 2022 Archives

On the Dangers of Cryptocurrencies and the Uselessness of Blockchain

Earlier this month, I and others wrote a letter to Congress, basically saying that cryptocurrencies are an complete and total disaster, and urging them to regulate the space. Nothing in that letter is out of the ordinary, and is in line with what I wrote about blockchain in 2019. In response, Matthew Green has written—not really a rebuttal—but a “a general response to some of the more common spurious objections…people make to public blockchain systems.” In it, he makes several broad points:

  1. Yes, current proof-of-work blockchains like bitcoin are terrible for the environment. But there are other modes like proof-of-stake that are not.
  2. Yes, a blockchain is an immutable ledger making it impossible to undo specific transactions. But that doesn’t mean there can’t be some governance system on top of the blockchain that enables reversals.
  3. Yes, bitcoin doesn’t scale and the fees are too high. But that’s nothing inherent in blockchain technology—that’s just a bunch of bad design choices bitcoin made.
  4. Blockchain systems can have a little or a lot of privacy, depending on how they are designed and implemented.

There’s nothing on that list that I disagree with. (We can argue about whether proof-of-stake is actually an improvement. I am skeptical of systems that enshrine a “they who have the gold make the rules” system of governance. And to the extent any of those scaling solutions work, they undo the decentralization blockchain claims to have.) But I also think that these defenses largely miss the point. To me, the problem isn’t that blockchain systems can be made slightly less awful than they are today. The problem is that they don’t do anything their proponents claim they do. In some very important ways, they’re not secure. They doesn’t replace trust with code; in fact, in many ways they are far less trustworthy than non-blockchain systems. They’re not decentralized, and their inevitable centralization is harmful because it’s largely emergent and ill-defined. They still have trusted intermediaries, often with more power and less oversight than non-blockchain systems. They still require governance. They still require regulation. (These things are what I wrote about here.) The problem with blockchain is that it’s not an improvement to any system—and often makes things worse.

In our letter, we write: “By its very design, blockchain technology is poorly suited for just about every purpose currently touted as a present or potential source of public benefit. From its inception, this technology has been a solution in search of a problem and has now latched onto concepts such as financial inclusion and data transparency to justify its existence, despite far better solutions to these issues already in use. Despite more than thirteen years of development, it has severe limitations and design flaws that preclude almost all applications that deal with public customer data and regulated financial transactions and are not an improvement on existing non-blockchain solutions.”

Green responds: “‘Public blockchain’ technology enables many stupid things: today’s cryptocurrency schemes can be venal, corrupt, overpromised. But the core technology is absolutely not useless. In fact, I think there are some pretty exciting things happening in the field, even if most of them are further away from reality than their boosters would admit.” I have yet to see one. More specifically, I can’t find a blockchain application whose value has anything to do with the blockchain part, that wouldn’t be made safer, more secure, more reliable, and just plain better by removing the blockchain part. I postulate that no one has ever said “Here is a problem that I have. Oh look, blockchain is a good solution.” In every case, the order has been: “I have a blockchain. Oh look, there is a problem I can apply it to.” And in no cases does it actually help.

Someone, please show me an application where blockchain is essential. That is, a problem that could not have been solved without blockchain that can now be solved with it. (And “ransomware couldn’t exist because criminals are blocked from using the conventional financial networks, and cash payments aren’t feasible” does not count.)

For example, Green complains that “credit card merchant fees are similar, or have actually risen in the United States since the 1990s.” This is true, but has little to do with technological inefficiencies or existing trust relationships in the industry. It’s because pretty much everyone who can and is paying attention gets 1% back on their purchases: in cash, frequent flier miles, or other affinity points. Green is right about how unfair this is. It’s a regressive subsidy, “since these fees are baked into the cost of most retail goods and thus fall heavily on the working poor (who pay them even if they use cash).” But that has nothing to do with the lack of blockchain, and solving it isn’t helped by adding a blockchain. It’s a regulatory problem; with a few exceptions, credit card companies have successfully pressured merchants into charging the same prices, whether someone pays in cash or with a credit card. Peer-to-peer payment systems like PayPal, Venmo, MPesa, and AliPay all get around those high transaction fees, and none of them use blockchain.

This is my basic argument: blockchain does nothing to solve any existing problem with financial (or other) systems. Those problems are inherently economic and political, and have nothing to do with technology. And, more importantly, technology can’t solve economic and political problems. Which is good, because adding blockchain causes a whole slew of new problems and makes all of these systems much, much worse.

Green writes: “I have no problem with the idea of legislators (intelligently) passing laws to regulate cryptocurrency. Indeed, given the level of insanity and the number of outright scams that are happening in this area, it’s pretty obvious that our current regulatory framework is not up to the task.” But when you remove the insanity and the scams, what’s left?

EDITED TO ADD: Nicholas Weaver is also adamant about this. David Rosenthal is good, too.

Posted on June 24, 2022 at 6:13 AM74 Comments

On the Subversion of NIST by the NSA

Nadiya Kostyuk and Susan Landau wrote an interesting paper: “Dueling Over DUAL_EC_DRBG: The Consequences of Corrupting a Cryptographic Standardization Process“:

Abstract: In recent decades, the U.S. National Institute of Standards and Technology (NIST), which develops cryptographic standards for non-national security agencies of the U.S. government, has emerged as the de facto international source for cryptographic standards. But in 2013, Edward Snowden disclosed that the National Security Agency had subverted the integrity of a NIST cryptographic standard­the Dual_EC_DRBG­enabling easy decryption of supposedly secured communications. This discovery reinforced the desire of some public and private entities to develop their own cryptographic standards instead of relying on a U.S. government process. Yet, a decade later, no credible alternative to NIST has emerged. NIST remains the only viable candidate for effectively developing internationally trusted cryptography standards.

Cryptographic algorithms are essential to security yet are hard to understand and evaluate. These technologies provide crucial security for communications protocols. Yet the protocols transit international borders; they are used by countries that do not necessarily trust each other. In particular, these nations do not necessarily trust the developer of the cryptographic standard.

Seeking to understand how NIST, a U.S. government agency, was able to remain a purveyor of cryptographic algorithms despite the Dual_EC_DRBG problem, we examine the Dual_EC_DRBG situation, NIST’s response, and why a non-regulatory, non-national security U.S. agency remains a successful international supplier of strong cryptographic solutions.

Posted on June 23, 2022 at 6:05 AM21 Comments

Symbiote Backdoor in Linux

Interesting:

What makes Symbiote different from other Linux malware that we usually come across, is that it needs to infect other running processes to inflict damage on infected machines. Instead of being a standalone executable file that is run to infect a machine, it is a shared object (SO) library that is loaded into all running processes using LD_PRELOAD (T1574.006), and parasitically infects the machine. Once it has infected all the running processes, it provides the threat actor with rootkit functionality, the ability to harvest credentials, and remote access capability.

News article:

Researchers have unearthed a discovery that doesn’t occur all that often in the realm of malware: a mature, never-before-seen Linux backdoor that uses novel evasion techniques to conceal its presence on infected servers, in some cases even with a forensic investigation.

No public attribution yet.

So far, there’s no evidence of infections in the wild, only malware samples found online. It’s unlikely this malware is widely active at the moment, but with stealth this robust, how can we be sure?

Posted on June 22, 2022 at 6:07 AM16 Comments

Hidden Anti-Cryptography Provisions in Internet Anti-Trust Bills

Two bills attempting to reduce the power of Internet monopolies are currently being debated in Congress: S. 2992, the American Innovation and Choice Online Act; and S. 2710, the Open App Markets Act. Reducing the power to tech monopolies would do more to “fix” the Internet than any other single action, and I am generally in favor of them both. (The Center for American Progress wrote a good summary and evaluation of them. I have written in support of the bill that would force Google and Apple to give up their monopolies on their phone app stores.)

There is a significant problem, though. Both bills have provisions that could be used to break end-to-end encryption.

Let’s start with S. 2992. Sec. 3(c)(7)(A)(iii) would allow a company to deny access to apps installed by users, where those app makers “have been identified [by the Federal Government] as national security, intelligence, or law enforcement risks.” That language is far too broad. It would allow Apple to deny access to an encryption service provider that provides encrypted cloud backups to the cloud (which Apple does not currently offer). All Apple would need to do is point to any number of FBI materials decrying the security risks with “warrant proof encryption.”

Sec. 3(c)(7)(A)(vi) states that there shall be no liability for a platform “solely” because it offers “end-to-end encryption.” This language is too narrow. The word “solely” suggests that offering end-to-end encryption could be a factor in determining liability, provided that it is not the only reason. This is very similar to one of the problems with the encryption carve-out in the EARN IT Act. The section also doesn’t mention any other important privacy-protective features and policies, which also shouldn’t be the basis for creating liability for a covered platform under Sec. 3(a).

In Sec. 2(a)(2), the definition of business user excludes any person who “is a clear national security risk.” This term is undefined, and as such far too broad. It can easily be interpreted to cover any company that offers an end-to-end encrypted alternative, or a service offered in a country whose privacy laws forbid disclosing data in response to US court-ordered surveillance. Again, the FBI’s repeated statements about end-to-end encryption could serve as support.

Finally, under Sec. 3(b)(2)(B), platforms have an affirmative defense for conduct that would otherwise violate the Act if they do so in order to “protect safety, user privacy, the security of nonpublic data, or the security of the covered platform.” This language is too vague, and could be used to deny users the ability to use competing services that offer better security/privacy than the incumbent platform—particularly where the platform offers subpar security in the name of “public safety.” For example, today Apple only offers unencrypted iCloud backups, which it can then turn over governments who claim this is necessary for “public safety.” Apple can raise this defense to justify its blocking third-party services from offering competing, end-to-end encrypted backups of iMessage and other sensitive data stored on an iPhone.

S. 2710 has similar problems. Sec 7. (6)(B) contains language specifying that the bill does not “require a covered company to interoperate or share data with persons or business users that…have been identified by the Federal Government as national security, intelligence, or law enforcement risks.” This would mean that Apple could ignore the prohibition against private APIs, and deny access to otherwise private APIs, for developers of encryption products that have been publicly identified by the FBI. That is, end-to-end encryption products.

I want those bills to pass, but I want those provisions cleared up so we don’t lose strong end-to-end encryption in our attempt to reign in the tech monopolies.

EDITED TO ADD (6/23): A few DC insiders have responded to me about this post. Their basic point is this: “Your threat model is wrong. The big tech companies can already break end-to-end encryption if they want. They don’t need any help, and this bill doesn’t give the FBI any new leverage they don’t already have. This bill doesn’t make anything any worse than it is today.” That’s a reasonable response. These bills are definitely a net positive for humanity.

Posted on June 21, 2022 at 6:34 AM34 Comments

Hertzbleed: A New Side-Channel Attack

Hertzbleed is a new side-channel attack that works against a variety of microprocressors. Deducing cryptographic keys by analyzing power consumption has long been an attack, but it’s not generally viable because measuring power consumption is often hard. This new attack measures power consumption by measuring time, making it easier to exploit.

The team discovered that dynamic voltage and frequency scaling (DVFS)—a power and thermal management feature added to every modern CPU—allows attackers to deduce the changes in power consumption by monitoring the time it takes for a server to respond to specific carefully made queries. The discovery greatly reduces what’s required. With an understanding of how the DVFS feature works, power side-channel attacks become much simpler timing attacks that can be done remotely.

The researchers have dubbed their attack Hertzbleed because it uses the insights into DVFS to expose­or bleed out­data that’s expected to remain private.

[…]

The researchers have already shown how the exploit technique they developed can be used to extract an encryption key from a server running SIKE, a cryptographic algorithm used to establish a secret key between two parties over an otherwise insecure communications channel.

The researchers said they successfully reproduced their attack on Intel CPUs from the 8th to the 11th generation of the Core microarchitecture. They also claimed that the technique would work on Intel Xeon CPUs and verified that AMD Ryzen processors are vulnerable and enabled the same SIKE attack used against Intel chips. The researchers believe chips from other manufacturers may also be affected.

Posted on June 20, 2022 at 6:23 AM34 Comments

Tracking People via Bluetooth on Their Phones

We’ve always known that phones—and the people carrying them—can be uniquely identified from their Bluetooth signatures, and that we need security techniques to prevent that. This new research shows that that’s not enough.

Computer scientists at the University of California San Diego proved in a study published May 24 that minute imperfections in phones caused during manufacturing create a unique Bluetooth beacon, one that establishes a digital signature or fingerprint distinct from any other device. Though phones’ Bluetooth uses cryptographic technology that limits trackability, using a radio receiver, these distortions in the Bluetooth signal can be discerned to track individual devices.

[…]

The study’s scientists conducted tests to show whether multiple phones being in one place could disrupt their ability to track individual signals. Results in an initial experiment showed they managed to discern individual signals for 40% of 162 devices in public. Another, scaled-up experiment showed they could discern 47% of 647 devices in a public hallway across two days.

The tracking range depends on device and the environment, and it could be several hundred feet, but in a crowded location it might only be 10 or so feet. Scientists were able to follow a volunteer’s signal as they went to and from their house. Certain environmental factors can disrupt a Bluetooth signal, including changes in environment temperature, and some devices send signals with more power and range than others.

One might say “well, I’ll just keep Bluetooth turned off when not in use,” but the researchers said they found that some devices, especially iPhones, don’t actually turn off Bluetooth unless a user goes directly into settings to turn off the signal. Most people might not even realize their Bluetooth is being constantly emitted by many smart devices.

Posted on June 17, 2022 at 6:06 AM22 Comments

Attacking the Performance of Machine Learning Systems

Interesting research: “Sponge Examples: Energy-Latency Attacks on Neural Networks“:

Abstract: The high energy costs of neural network training and inference led to the use of acceleration hardware such as GPUs and TPUs. While such devices enable us to train large-scale neural networks in datacenters and deploy them on edge devices, their designers’ focus so far is on average-case performance. In this work, we introduce a novel threat vector against neural networks whose energy consumption or decision latency are critical. We show how adversaries can exploit carefully-crafted sponge examples, which are inputs designed to maximise energy consumption and latency, to drive machine learning (ML) systems towards their worst-case performance. Sponge examples are, to our knowledge, the first denial-of-service attack against the ML components of such systems. We mount two variants of our sponge attack on a wide range of state-of-the-art neural network models, and find that language models are surprisingly vulnerable. Sponge examples frequently increase both latency and energy consumption of these models by a factor of 30×. Extensive experiments show that our new attack is effective across different hardware platforms (CPU, GPU and an ASIC simulator) on a wide range of different language tasks. On vision tasks, we show that sponge examples can be produced and a latency degradation observed, but the effect is less pronounced. To demonstrate the effectiveness of sponge examples in the real world, we mount an attack against Microsoft Azure’s translator and show an increase of response time from 1ms to 6s (6000×). We conclude by proposing a defense strategy: shifting the analysis of energy consumption in hardware from an average-case to a worst-case perspective.

Attackers were able to degrade the performance so much, and force the system to waste so many cycles, that some hardware would shut down due to overheating. Definitely a “novel threat vector.”

Posted on June 16, 2022 at 6:02 AM7 Comments

M1 Chip Vulnerability

This is a new vulnerability against Apple’s M1 chip. Researchers say that it is unpatchable.

Researchers from MIT’s Computer Science and Artificial Intelligence Laboratory, however, have created a novel hardware attack, which combines memory corruption and speculative execution attacks to sidestep the security feature. The attack shows that pointer authentication can be defeated without leaving a trace, and as it utilizes a hardware mechanism, no software patch can fix it.

The attack, appropriately called “Pacman,” works by “guessing” a pointer authentication code (PAC), a cryptographic signature that confirms that an app hasn’t been maliciously altered. This is done using speculative execution—a technique used by modern computer processors to speed up performance by speculatively guessing various lines of computation—to leak PAC verification results, while a hardware side-channel reveals whether or not the guess was correct.

What’s more, since there are only so many possible values for the PAC, the researchers found that it’s possible to try them all to find the right one.

It’s not obvious how to exploit this vulnerability in the wild, so I’m unsure how important this is. Also, I don’t know if it also applies to Apple’s new M2 chip.

Research paper. Another news article.

Posted on June 15, 2022 at 6:05 AM20 Comments

Hacking Tesla’s Remote Key Cards

Interesting vulnerability in Tesla’s NFC key cards:

Martin Herfurt, a security researcher in Austria, quickly noticed something odd about the new feature: Not only did it allow the car to automatically start within 130 seconds of being unlocked with the NFC card, but it also put the car in a state to accept entirely new keys—with no authentication required and zero indication given by the in-car display.

“The authorization given in the 130-second interval is too general… [it’s] not only for drive,” Herfurt said in an online interview. “This timer has been introduced by Tesla…in order to make the use of the NFC card as a primary means of using the car more convenient. What should happen is that the car can be started and driven without the user having to use the key card a second time. The problem: within the 130-second period, not only the driving of the car is authorized, but also the [enrolling] of a new key.”

Posted on June 14, 2022 at 7:19 AM7 Comments

Cryptanalysis of ENCSecurity’s Encryption Implementation

ENCSecurity markets a file encryption system, and it’s used by SanDisk, Sony, Lexar, and probably others. Despite it using AES as its algorithm, its implementation is flawed in multiple ways—and breakable.

The moral is, as it always is, that implementing cryptography securely is hard. Don’t roll your own anything if you can help it.

Posted on June 13, 2022 at 6:48 AM30 Comments

Smartphones and Civilians in Wartime

Interesting article about civilians using smartphones to assist their militaries in wartime, and how that blurs the important legal distinction between combatants and non-combatants:

The principle of distinction between the two roles is a critical cornerstone of international humanitarian law­—the law of armed conflict, codified by decades of customs and laws such as the Geneva Conventions. Those considered civilians and civilian targets are not to be attacked by military forces; as they are not combatants, they should be spared. At the same time, they also should not act as combatants—­if they do, they may lose this status.

The conundrum, then, is how to classify a civilian who, with the use of their smartphone, potentially becomes an active participant in a military sensor system. (To be clear, solely having the app installed is not sufficient to lose the protected status. What matters is actual usage.) The Additional Protocol I to Geneva Conventions states that civilians enjoy protection from the “dangers arising from military operations unless and for such time as they take a direct part in hostilities.” Legally, if civilians engage in military activity, such as taking part in hostilities by using weapons, they forfeit their protected status, “for such time as they take a direct part in hostilities” that “affect[s] the military operations,” according to the International Committee of the Red Cross, the traditional impartial custodian of International Humanitarian Law. This is the case even if the people in question are not formally members of the armed forces. By losing the status of a civilian, one may become a legitimate military objective, carrying the risk of being directly attacked by military forces.

Posted on June 9, 2022 at 6:22 AM27 Comments

Remotely Controlling Touchscreens

Researchers have demonstrated controlling touchscreens at a distance, at least in a laboratory setting:

The core idea is to take advantage of the electromagnetic signals to execute basic touch events such as taps and swipes into targeted locations of the touchscreen with the goal of taking over remote control and manipulating the underlying device.

The attack, which works from a distance of up to 40mm, hinges on the fact that capacitive touchscreens are sensitive to EMI, leveraging it to inject electromagnetic signals into transparent electrodes that are built into the touchscreen so as to register them as touch events.

The experimental setup involves an electrostatic gun to generate a strong pulse signal that’s then sent to an antenna to transmit an electromagnetic field to the phone’s touchscreen, thereby causing the electrodes ­ which act as antennas themselves ­ to pick up the EMI.

Paper: “GhostTouch: Targeted Attacks on Touchscreens without Physical Touch“:

Abstract: Capacitive touchscreens have become the primary human-machine interface for personal devices such as smartphones and tablets. In this paper, we present GhostTouch, the first active contactless attack against capacitive touchscreens. GhostTouch uses electromagnetic interference (EMI) to inject fake touch points into a touchscreen without the need to physically touch it. By tuning the parameters of the electromagnetic signal and adjusting the antenna, we can inject two types of basic touch events, taps and swipes, into targeted locations of the touchscreen and control them to manipulate the underlying device. We successfully launch the GhostTouch attacks on nine smartphone models. We can inject targeted taps continuously with a standard deviation of as low as 14.6 x 19.2 pixels from the target area, a delay of less than 0.5s and a distance of up to 40mm. We show the real-world impact of the GhostTouch attacks in a few proof-of-concept scenarios, including answering an eavesdropping phone call, pressing the button, swiping up to unlock, and entering a password. Finally, we discuss potential hardware and software countermeasures to mitigate the attack.

Posted on June 2, 2022 at 3:59 PM15 Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.