Entries Tagged "cryptocurrency"

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Smart Contract Bug Results in $31 Million Loss

A hacker stole $31 million from the blockchain company MonoX Finance , by exploiting a bug in software the service uses to draft smart contracts.

Specifically, the hack used the same token as both the tokenIn and tokenOut, which are methods for exchanging the value of one token for another. MonoX updates prices after each swap by calculating new prices for both tokens. When the swap is completed, the price of tokenIn­that is, the token sent by the user­decreases and the price of tokenOut­or the token received by the user­increases.

By using the same token for both tokenIn and tokenOut, the hacker greatly inflated the price of the MONO token because the updating of the tokenOut overwrote the price update of the tokenIn. The hacker then exchanged the token for $31 million worth of tokens on the Ethereum and Polygon blockchains.

The article goes on to talk about how common these sorts of attacks are. The basic problem is that the code is the ultimate authority—there is no adjudication protocol—so if there’s a vulnerability in the code, there is no recourse. And, of course, there are lots of vulnerabilities in code.

To me, this is reason enough never to use smart contracts for anything important. Human-based adjudication systems are not useless pre-Internet human baggage, they’re vital.

Posted on December 2, 2021 at 8:32 AMView Comments

Wire Fraud Scam Upgraded with Bitcoin

The FBI has issued a bulletin describing a bitcoin variant of a wire fraud scam:

As the agency describes it, the scammer will contact their victim and somehow convince them that they need to send money, either with promises of love, further riches, or by impersonating an actual institution like a bank or utility company. After the mark is convinced, the scammer will have them get cash (sometimes out of investment or retirement accounts), and head to an ATM that sells cryptocurrencies and supports reading QR codes. Once the victim’s there, they’ll scan a QR code that the scammer sent them, which will tell the machine to send any crypto purchased to the scammer’s address. Just like that, the victim loses their money, and the scammer has successfully exploited them.

[…]

The “upgrade” (as it were) for scammers with the crypto ATM method is two-fold: it can be less friction than sending a wire transfer, and at the end the scammer has cryptocurrency instead of fiat. With wire transfers, you have to fill out a form, and you may give that form to an actual person (who could potentially vibe check you). Using the ATM method, there’s less time to reflect on the fact that you’re about to send money to a stranger. And, if you’re a criminal trying to get your hands on Bitcoin, you won’t have to teach your targets how to buy coins on the internet and transfer them to another wallet—they probably already know how to use an ATM and scan a QR code.

Posted on November 16, 2021 at 6:18 AMView Comments

Friday Squid Blogging: Squid Game Cryptocurrency Was a Scam

The Squid Game cryptocurrency was a complete scam:

The SQUID cryptocurrency peaked at a price of $2,861 before plummeting to $0 around 5:40 a.m. ET., according to the website CoinMarketCap. This kind of theft, commonly called a “rug pull” by crypto investors, happens when the creators of the crypto quickly cash out their coins for real money, draining the liquidity pool from the exchange.

I don’t know why anyone would trust an investment—any investment—that you could buy but not sell.

Wired story.

As usual, you can also use this squid post to talk about the security stories in the news that I haven’t covered.

Read my blog posting guidelines here.

Posted on November 5, 2021 at 4:11 PMView Comments

Disrupting Ransomware by Disrupting Bitcoin

Ransomware isn’t new; the idea dates back to 1986 with the “Brain” computer virus. Now, it’s become the criminal business model of the internet for two reasons. The first is the realization that no one values data more than its original owner, and it makes more sense to ransom it back to them—sometimes with the added extortion of threatening to make it public—than it does to sell it to anyone else. The second is a safe way of collecting ransoms: bitcoin.

This is where the suggestion to ban cryptocurrencies as a way to “solve” ransomware comes from. Lee Reiners, executive director of the Global Financial Markets Center at Duke Law, proposed this in a recent Wall Street Journal op-ed. Journalist Jacob Silverman made the same proposal in a New Republic essay. Without this payment channel, they write, the major ransomware epidemic is likely to vanish, since the only payment alternatives are suitcases full of cash or the banking system, both of which have severe limitations for criminal enterprises.

It’s the same problem kidnappers have had for centuries. The riskiest part of the operation is collecting the ransom. That’s when the criminal exposes themselves, by telling the payer where to leave the money. Or gives out their banking details. This is how law enforcement tracks kidnappers down and arrests them. The rise of an anonymous, global, distributed money-transfer system outside of any national control is what makes computer ransomware possible.

This problem is made worse by the nature of the criminals. They operate out of countries that don’t have the resources to prosecute cybercriminals, like Nigeria; or protect cybercriminals that only attack outside their borders, like Russia; or use the proceeds as a revenue stream, like North Korea. So even when a particular group is identified, it is often impossible to prosecute. Which leaves the only tools left a combination of successfully blocking attacks (another hard problem) and eliminating the payment channels that the criminals need to turn their attacks into profit.

In this light, banning cryptocurrencies like bitcoin is an obvious solution. But while the solution is conceptually simple, it’s also impossible because—despite its overwhelming problems—there are so many legitimate interests using cryptocurrencies, albeit largely for speculation and not for legal payments.

We suggest an easier alternative: merely disrupt the cryptocurrency markets. Making them harder to use will have the effect of making them less useful as a ransomware payment vehicle, and not just because victims will have more difficulty figuring out how to pay. The reason requires understanding how criminals collect their profits.

Paying a ransom starts with a victim turning a large sum of money into bitcoin and then transferring it to a criminal controlled “account.” Bitcoin is, in itself, useless to the criminal. You can’t actually buy much with bitcoin. It’s more like casino chips, only usable in a single establishment for a single purpose. (Yes, there are companies that “accept” bitcoin, but that is mostly a PR stunt.) A criminal needs to convert the bitcoin into some national currency that he can actually save, spend, invest, or whatever.

This is where it gets interesting. Conceptually, bitcoin combines numbered Swiss bank accounts with public transactions and balances. Anyone can create as many anonymous accounts as they want, but every transaction is posted publicly for the entire world to see. This creates some important challenges for these criminals.

First, the criminal needs to take efforts to conceal the bitcoin. In the old days, criminals used “mixing services“: third parties that would accept bitcoin into one account and then return it (minus a fee) from an unconnected set of accounts. Modern bitcoin tracing tools make this money laundering trick ineffective. Instead, the modern criminal does something called “chain swaps.”

In a chain swap, the criminal transfers the bitcoin to a shady offshore cryptocurrency exchange. These exchanges are notoriously weak about enforcing money laundering laws and—for the most part—don’t have access to the banking system. Once on this alternate exchange, the criminal sells his bitcoin and buys some other cryptocurrency like Ethereum, Dogecoin, Tether, Monero, or one of dozens of others. They then transfer it to another shady offshore exchange and transfer it back into bitcoin. Voila­—they now have “clean” bitcoin.

Second, the criminal needs to convert that bitcoin into spendable money. They take their newly cleaned bitcoin and transfer it to yet another exchange, one connected to the banking system. Or perhaps they hire someone else to do this step. These exchanges conduct greater oversight of their customers, but the criminal can use a network of bogus accounts, recruit a bunch of users to act as mules, or simply bribe an employee at the exchange to evade whatever laws there. The end result of this activity is to turn the bitcoin into dollars, euros, or some other easily usable currency.

Both of these steps—the chain swapping and currency conversion—require a large amount of normal activity to keep from standing out. That is, they will be easy for law enforcement to identify unless they are hiding among lots of regular, noncriminal transactions. If speculators stopped buying and selling cryptocurrencies and the market shrunk drastically, these criminal activities would no longer be easy to conceal: there’s simply too much money involved.

This is why disruption will work. It doesn’t require an outright ban to stop these criminals from using bitcoin—just enough sand in the gears in the cryptocurrency space to reduce its size and scope.

How do we do this?

The first mechanism observes that the criminal’s flows have a unique pattern. The overall cryptocurrency space is “zero sum”: Every dollar made was provided by someone else. And the primary legal use of cryptocurrencies involves speculation: people effectively betting on a currency’s future value. So the background speculators are mostly balanced: One bitcoin in results in one bitcoin out. There are exceptions involving offshore exchanges and speculation among different cryptocurrencies, but they’re marginal, and only involve turning one bitcoin into a little more (if a speculator is lucky) or a little less (if unlucky).

Criminals and their victims act differently. Victims are net buyers, turning millions of dollars into bitcoin and never going the other way. Criminals are net sellers, only turning bitcoin into currency. The only other net sellers are the cryptocurrency miners, and they are easy to identify.

Any banked exchange that cares about enforcing money laundering laws must consider all significant net sellers of cryptocurrencies as potential criminals and report them to both in-country and US financial authorities. Any exchange that doesn’t should have its banking forcefully cut.

The US Treasury can ensure these exchanges are cut out of the banking system. By designating a rogue but banked exchange, the Treasury says that it is illegal not only to do business with the exchange but for US banks to do business with the exchange’s bank. As a consequence, the rogue exchange would quickly find its banking options eliminated.

A second mechanism involves the IRS. In 2019, it started demanding information from cryptocurrency exchanges and added a check box to the 1040 form that requires disclosure from those who both buy and sell cryptocurrencies. And while this is intended to target tax evasion, it has the side consequence of disrupting those offshore exchanges criminals rely to launder their bitcoin. Speculation on cryptocurrency is far less attractive since the speculators have to pay taxes but most exchanges don’t help out by filing 1099-Bs that make it easy to calculate the taxes owed.

A third mechanism involves targeting the cryptocurrency Tether. While most cryptocurrencies have values that fluctuate with demand, Tether is a “stablecoin” that is supposedly backed one-to-one with dollars. Of course, it probably isn’t, as its claim to be the seventh largest holder of commercial paper (short-term loans to major businesses) is blatantly untrue. Instead, they appear part of a cycle where new Tether is issued, used to buy cryptocurrencies, and the resulting cryptocurrencies now “back” Tether and drive up the price.

This behavior is clearly that of a “wildcat bank,” an 1800s fraudulent banking style that has long been illegal. Tether also bears a striking similarity to Liberty Reserve, an online currency that the Department of Justice successfully prosecuted for money laundering in 2013. Shutting down Tether would have the side effect of eliminating the value proposition for the exchanges that support chain swapping, since these exchanges need a “stable” value for the speculators to trade against.

There are further possibilities. One involves treating the cryptocurrency miners, those who validate all transactions and add them to the public record, as money transmitters—and subject to the regulations around that business. Another option involves requiring cryptocurrency exchanges to actually deliver the cryptocurrencies into customer-controlled wallets.

Effectively, all cryptocurrency exchanges avoid transferring cryptocurrencies between customers. Instead, they simply record entries in a central database. This makes sense because actual “on chain” transactions can be particularly expensive for cryptocurrencies like bitcoin or Ethereum. If all speculators needed to actually receive their bitcoins, it would make clear that its value proposition as a currency simply doesn’t exist, as the already strained system would grind to a halt.

And, of course, law enforcement can already target criminals’ bitcoin directly. An example of this just occurred, when US law enforcement was able to seize 85% of the $4 million ransom Colonial Pipeline paid to the criminal organization DarkSide. That by the time the seizure occurred the bitcoin lost more than 30% of its value is just one more reminder of how unworkable bitcoin is as a “store of value.”

There is no single silver bullet to disrupt either cryptocurrencies or ransomware. But enough little disruptions, a “death of a thousand cuts” through new and existing regulation, should make bitcoin no longer usable for ransomware. And if there’s no safe way for a criminal to collect the ransom, their business model becomes no longer viable.

This essay was written with Nicholas Weaver, and previously appeared on Slate.com.

Posted on July 26, 2021 at 6:30 AMView Comments

Ransomware Is Getting Ugly

Modern ransomware has two dimensions: pay to get your data back, and pay not to have your data dumped on the Internet. The DC police are the victims of this ransomware, and the criminals have just posted personnel records—”including the results of psychological assessments and polygraph tests; driver’s license images; fingerprints; social security numbers; dates of birth; and residential, financial, and marriage histories”—for two dozen police officers.

The negotiations don’t seem to be doing well. The criminals want $4M. The DC police offered them $100,000.

The Colonial Pipeline is another current high-profile ransomware victim. (Brian Krebs has some good information on DarkSide, the criminal group behind that attack.) So is Vastaamo, a Finnish mental heal clinic. Criminals contacted the individual patients and demanded payment, and then dumped their personal psychological information online.

An industry group called the Institute for Security and Technology (no, I haven’t heard of it before, either) just released a comprehensive report on combating ransomware. It has a “comprehensive plan of action,” which isn’t much different from anything most of us can propose. Solving this is not easy. Ransomware is big business, made possible by insecure networks that allow criminals to gain access to networks in the first place, and cryptocurrencies that allow for payments that governments cannot interdict. Ransomware has become the most profitable cybercrime business model, and until we solve those two problems, that’s not going to change.

Posted on May 14, 2021 at 6:30 AMView Comments

Identifying the Person Behind Bitcoin Fog

The person behind the Bitcoin Fog was identified and arrested. Bitcoin Fog was an anonymization service: for a fee, it mixed a bunch of people’s bitcoins up so that it was hard to figure out where any individual coins came from. It ran for ten years.

Identifying the person behind Bitcoin Fog serves as an illustrative example of how hard it is to be anonymous online in the face of a competent police investigation:

Most remarkable, however, is the IRS’s account of tracking down Sterlingov using the very same sort of blockchain analysis that his own service was meant to defeat. The complaint outlines how Sterlingov allegedly paid for the server hosting of Bitcoin Fog at one point in 2011 using the now-defunct digital currency Liberty Reserve. It goes on to show the blockchain evidence that identifies Sterlingov’s purchase of that Liberty Reserve currency with bitcoins: He first exchanged euros for the bitcoins on the early cryptocurrency exchange Mt. Gox, then moved those bitcoins through several subsequent addresses, and finally traded them on another currency exchange for the Liberty Reserve funds he’d use to set up Bitcoin Fog’s domain.

Based on tracing those financial transactions, the IRS says, it then identified Mt. Gox accounts that used Sterlingov’s home address and phone number, and even a Google account that included a Russian-language document on its Google Drive offering instructions for how to obscure Bitcoin payments. That document described exactly the steps Sterlingov allegedly took to buy the Liberty Reserve funds he’d used.

Posted on May 3, 2021 at 9:36 AMView Comments

Signal Adds Cryptocurrency Support

According to Wired, Signal is adding support for the cryptocurrency MobileCoin, “a form of digital cash designed to work efficiently on mobile devices while protecting users’ privacy and even their anonymity.”

Moxie Marlinspike, the creator of Signal and CEO of the nonprofit that runs it, describes the new payments feature as an attempt to extend Signal’s privacy protections to payments with the same seamless experience that Signal has offered for encrypted conversations. “There’s a palpable difference in the feeling of what it’s like to communicate over Signal, knowing you’re not being watched or listened to, versus other communication platforms,” Marlinspike told WIRED in an interview. “I would like to get to a world where not only can you feel that when you talk to your therapist over Signal, but also when you pay your therapist for the session over Signal.”

I think this is an incredibly bad idea. It’s not just the bloating of what was a clean secure communications app. It’s not just that blockchain is just plain stupid. It’s not even that Signal is choosing to tie itself to a specific blockchain currency. It’s that adding a cryptocurrency to an end-to-end encrypted app muddies the morality of the product, and invites all sorts of government investigative and regulatory meddling: by the IRS, the SEC, FinCEN, and probably the FBI.

And I see no good reason to do this. Secure communications and secure transactions can be separate apps, even separate apps from the same organization. End-to-end encryption is already at risk. Signal is the best app we have out there. Combining it with a cryptocurrency means that the whole system dies if any part dies.

EDITED TO ADD: Commentary from Stephen Deihl:

I think I speak for many technologists when I say that any bolted-on cryptocurrency monetization scheme smells like a giant pile of rubbish and feels enormously user-exploitative. We’ve seen this before, after all Telegram tried the same thing in an ICO that imploded when SEC shut them down, and Facebook famously tried and failed to monetize WhatsApp through their decentralized-but-not-really digital money market fund project.

[…]

Signal is a still a great piece of software. Just do one thing and do it well, be the trusted de facto platform for private messaging that empowers dissidents, journalists and grandma all to communicate freely with the same guarantees of privacy. Don’t become a dodgy money transmitter business. This is not the way.

EDITED TO ADD (4/14): Moxie Marlinspike is on the advisory board for MobileCoin, which was designed for the purpose of providing a payment function in Signal.

Posted on April 7, 2021 at 6:24 AMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.