Posts Tagged: Stas Alforov


30
Jul 20

Is Your Chip Card Secure? Much Depends on Where You Bank

Chip-based credit and debit cards are designed to make it infeasible for skimming devices or malware to clone your card when you pay for something by dipping the chip instead of swiping the stripe. But a recent series of malware attacks on U.S.-based merchants suggest thieves are exploiting weaknesses in how certain financial institutions have implemented the technology to sidestep key chip card security features and effectively create usable, counterfeit cards.

A chip-based credit card. Image: Wikipedia.

Traditional payment cards encode cardholder account data in plain text on a magnetic stripe, which can be read and recorded by skimming devices or malicious software surreptitiously installed in payment terminals. That data can then be encoded onto anything else with a magnetic stripe and used to place fraudulent transactions.

Newer, chip-based cards employ a technology known as EMV that encrypts the account data stored in the chip. The technology causes a unique encryption key — referred to as a token or “cryptogram” — to be generated each time the chip card interacts with a chip-capable payment terminal.

Virtually all chip-based cards still have much of the same data that’s stored in the chip encoded on a magnetic stripe on the back of the card. This is largely for reasons of backward compatibility since many merchants — particularly those in the United States — still have not fully implemented chip card readers. This dual functionality also allows cardholders to swipe the stripe if for some reason the card’s chip or a merchant’s EMV-enabled terminal has malfunctioned.

But there are important differences between the cardholder data stored on EMV chips versus magnetic stripes. One of those is a component in the chip known as an integrated circuit card verification value or “iCVV” for short — also known as a “dynamic CVV.”

The iCVV differs from the card verification value (CVV) stored on the physical magnetic stripe, and protects against the copying of magnetic-stripe data from the chip and the use of that data to create counterfeit magnetic stripe cards. Both the iCVV and CVV values are unrelated to the three-digit security code that is visibly printed on the back of a card, which is used mainly for e-commerce transactions or for card verification over the phone.

The appeal of the EMV approach is that even if a skimmer or malware manages to intercept the transaction information when a chip card is dipped, the data is only valid for that one transaction and should not allow thieves to conduct fraudulent payments with it going forward.

However, for EMV’s security protections to work, the back-end systems deployed by card-issuing financial institutions are supposed to check that when a chip card is dipped into a chip reader, only the iCVV is presented; and conversely, that only the CVV is presented when the card is swiped. If somehow these do not align for a given transaction type, the financial institution is supposed to decline the transaction.

The trouble is that not all financial institutions have properly set up their systems this way. Unsurprisingly, thieves have known about this weakness for years. In 2017, I wrote about the increasing prevalence of “shimmers,” high-tech card skimming devices made to intercept data from chip card transactions.

A close-up of a shimmer found on a Canadian ATM. Source: RCMP.

More recently, researchers at Cyber R&D Labs published a paper detailing how they tested 11 chip card implementations from 10 different banks in Europe and the U.S. The researchers found they could harvest data from four of them and create cloned magnetic stripe cards that were successfully used to place transactions.

There are now strong indications the same method detailed by Cyber R&D Labs is being used by point-of-sale (POS) malware to capture EMV transaction data that can then be resold and used to fabricate magnetic stripe copies of chip-based cards.

Earlier this month, the world’s largest payment card network Visa released a security alert regarding a recent merchant compromise in which known POS malware families were apparently modified to target EMV chip-enabled POS terminals.

“The implementation of secure acceptance technology, such as EMV® Chip, significantly reduced the usability of the payment account data by threat actors as the available data only included personal account number (PAN), integrated circuit card verification value (iCVV) and expiration date,” Visa wrote. “Thus, provided iCVV is validated properly, the risk of counterfeit fraud was minimal. Additionally, many of the merchant locations employed point-to-point encryption (P2PE) which encrypted the PAN data and further reduced the risk to the payment accounts processed as EMV® Chip.”

Visa did not name the merchant in question, but something similar seems to have happened at Key Food Stores Co-Operative Inc., a supermarket chain in the northeastern United States. Key Food initially disclosed a card breach in March 2020, but two weeks ago updated its advisory to clarify that EMV transaction data also was intercepted.

“The POS devices at the store locations involved were EMV enabled,” Key Food explained. “For EMV transactions at these locations, we believe only the card number and expiration date would have been found by the malware (but not the cardholder name or internal verification code).”

While Key Food’s statement may be technically accurate, it glosses over the reality that the stolen EMV data could still be used by fraudsters to create magnetic stripe versions of EMV cards presented at the compromised store registers in cases where the card-issuing bank hadn’t implemented EMV correctly. Continue reading →


30
Jun 20

COVID-19 ‘Breach Bubble’ Waiting to Pop?

The COVID-19 pandemic has made it harder for banks to trace the source of payment card data stolen from smaller, hacked online merchants. On the plus side, months of quarantine have massively decreased demand for account information that thieves buy and use to create physical counterfeit credit cards. But fraud experts say recent developments suggest both trends are about to change — and likely for the worse.

The economic laws of supply and demand hold just as true in the business world as they do in the cybercrime space. Global lockdowns from COVID-19 have resulted in far fewer fraudsters willing or able to visit retail stores to use their counterfeit cards, and the decreased demand has severely depressed prices in the underground for purloined card data.

An ad for a site selling stolen payment card data, circa March 2020.

That’s according to Gemini Advisory, a New York-based cyber intelligence firm that closely tracks the inventories of dark web stores trafficking in stolen payment card data.

Stas Alforov, Gemini’s director of research and development, said that since the beginning of 2020 the company has seen a steep drop in demand for compromised “card present” data — digits stolen from hacked brick-and-mortar merchants with the help of malicious software surreptitiously installed on point-of-sale (POS) devices.

Alforov said the median price for card-present data has dropped precipitously over the past few months.

“Gemini Advisory has seen over 50 percent decrease in demand for compromised card present data since the mandated COVID-19 quarantines in the United States as well as the majority of the world,” he told KrebsOnSecurity.

Meanwhile, the supply of card-present data has remained relatively steady. Gemini’s latest find — a 10-month-long card breach at dozens of Chicken Express locations throughout Texas and other southern states that the fast-food chain first publicly acknowledged today after being contacted by this author — saw an estimated 165,000 cards stolen from eatery locations recently go on sale at one of the dark web’s largest cybercrime bazaars.

“Card present data supply hasn’t wavered much during the COVID-19 period,” Alforov said. “This is likely due to the fact that most of the sold data is still coming from breaches that occurred in 2019 and early 2020.”

A lack of demand for and steady supply of stolen card-present data in the underground has severely depressed prices since the beginning of the COVID-19 pandemic. Image: Gemini Advisory

Naturally, crooks who ply their trade in credit card thievery also have been working from home more throughout the COVID-19 pandemic. That means demand for stolen “card-not-present” data — customer payment information extracted from hacked online merchants and typically used to defraud other e-commerce vendors — remains high. And so have prices for card-not-present data: Gemini found prices for this commodity actually increased slightly over the past few months.

Andrew Barratt is an investigator with Coalfire, the cyber forensics firm hired by Chicken Express to remediate the breach and help the company improve security going forward. Barratt said there’s another curious COVID-19 dynamic going on with e-commerce fraud recently that is making it more difficult for banks and card issuers to trace patterns in stolen card-not-present data back to hacked web merchants — particularly smaller e-commerce shops.

“One of the concerns that has been expressed to me is that we’re getting [fewer] overlapping hotspots,” Barratt said. “For a lot of the smaller, more frequently compromised merchants there has been a large drop off in transactions. Whilst big e-commerce has generally done okay during the COVID-19 pandemic, a number of more modest sized or specialty online retailers have not had the same access to their supply chain and so have had to close or drastically reduce the lines they’re selling.”

Banks routinely take groups of customer cards that have experienced fraudulent activity and try to see if some or all of them were used at the same merchant during a similar timeframe, a basic anti-fraud process known as “common point of purchase” or CPP analysis. But ironically, this analysis can become more challenging when there are fewer overall transactions going through a compromised merchant’s site, Barratt said.

“With a smaller transactional footprint means less Common Point of Purchase alerts and less data to work on to trigger a forensic investigation or fraud alert,” Barratt said. “It does also mean less fraud right now – which is a positive. But one of the big concerns that has been raised to us as investigators — literally asking if we have capacity for what’s coming — has been that merchants are getting compromised by ‘lie in wait’ type intruders.”

Barratt says there’s a suspicion that hackers may have established beachheads [breachheads?] in a number of these smaller online merchants and are simply biding their time. If and when transaction volumes for these merchants do pick up, the concern is then hackers may be in a better position to mix the sale of cards stolen from many hacked merchants and further confound CPP analysis efforts. Continue reading →


30
Apr 20

How Cybercriminals are Weathering COVID-19

In many ways, the COVID-19 pandemic has been a boon to cybercriminals: With unprecedented numbers of people working from home and anxious for news about the virus outbreak, it’s hard to imagine a more target-rich environment for phishers, scammers and malware purveyors. In addition, many crooks are finding the outbreak has helped them better market their cybercriminal wares and services. But it’s not all good news: The Coronavirus also has driven up costs and disrupted key supply lines for many cybercriminals. Here’s a look at how they’re adjusting to these new realities.

FUELED BY MULES

One of the more common and perennial cybercriminal schemes is “reshipping fraud,” wherein crooks buy pricey consumer goods online using stolen credit card data and then enlist others to help them collect or resell the merchandise.

Most online retailers years ago stopped shipping to regions of the world most frequently associated with credit card fraud, including Eastern Europe, North Africa, and Russia. These restrictions have created a burgeoning underground market for reshipping scams, which rely on willing or unwitting residents in the United States and Europe — derisively referred to as “reshipping mules” — to receive and relay high-dollar stolen goods to crooks living in the embargoed areas.

A screen shot from a user account at “Snowden,” a long-running reshipping mule service.

But apparently a number of criminal reshipping services are reporting difficulties due to the increased wait time when calling FedEx or UPS (to divert carded goods that merchants end up shipping to the cardholder’s address instead of to the mule’s). In response, these operations are raising their prices and warning of longer shipping times, which in turn could hamper the activities of other actors who depend on those services.

That’s according to Intel 471, a cyber intelligence company that closely monitors hundreds of online crime forums. In a report published today, the company said since late March 2020 it has observed several crooks complaining about COVID-19 interfering with the daily activities of their various money mules (people hired to help launder the proceeds of cybercrime).

“One Russian-speaking actor running a fraud network complained about their subordinates (“money mules”) in Italy, Spain and other countries being unable to withdraw funds, since they currently were afraid to leave their homes,” Intel 471 observed. “Also some actors have reported that banks’ customer-support lines are being overloaded, making it difficult for fraudsters to call them for social-engineering activities (such as changing account ownership, raising withdrawal limits, etc).”

Still, every dark cloud has a silver lining: Intel 471 noted many cybercriminals appear optimistic that the impending global economic recession (and resultant unemployment) “will make it easier to recruit low-level accomplices such as money mules.”

Alex Holden, founder and CTO of Hold Security, agreed. He said while the Coronavirus has forced reshipping operators to make painful shifts in several parts of their business, the overall market for available mules has never looked brighter.

“Reshipping is way up right now, but there are some complications,” he said.

For example, reshipping scams have over the years become easier for both reshipping mule operators and the mules themselves. Many reshipping mules are understandably concerned about receiving stolen goods at their home and risking a visit from the local police. But increasingly, mules have been instructed to retrieve carded items from third-party locations.

“The mules don’t have to receive stolen goods directly at home anymore,” Holden said. “They can pick them up at Walgreens, Hotel lobbies, etc. There are a ton of reshipment tricks out there.”

But many of those tricks got broken with the emergence of COVID-19 and social distancing norms. In response, more mule recruiters are asking their hires to do things like reselling goods shipped to their homes on platforms like eBay and Amazon.

“Reshipping definitely has become more complicated,” Holden said. “Not every mule will run 10 times a day to the post office, and some will let the goods sit by the mailbox for days. But on the whole, mules are more compliant these days.”

GIVE AND TAKE

KrebsOnSecurity recently came to a similar conclusion: Last month’s story, “Coronavirus Widens the Money Mule Pool,” looked at one money mule operation that had ensnared dozens of mules with phony job offers in a very short period of time. Incidentally, the fake charity behind that scheme — which promised to raise money for Coronavirus victims — has since closed up shop and apparently re-branded itself as the Tessaris Foundation.

Charitable cybercriminal endeavors were the subject of a report released this week by cyber intel firm Digital Shadows, which looked at various ways computer crooks are promoting themselves and their hacking services using COVID-19 themed discounts and giveaways.

Like many commercials on television these days, such offers obliquely or directly reference the economic hardships wrought by the virus outbreak as a way of connecting on an emotional level with potential customers.

“The illusion of philanthropy recedes further when you consider the benefits to the threat actors giving away goods and services,” the report notes. “These donors receive a massive boost to their reputation on the forum. In the future, they may be perceived as individuals willing to contribute to forum life, and the giveaways help establish a track record of credibility.”

Brian’s Club — one of the underground’s largest bazaars for selling stolen credit card data and one that has misappropriated this author’s likeness and name in its advertising — recently began offering “pandemic support” in the form of discounts for its most loyal customers.

Continue reading →


30
Apr 19

Data: E-Retail Hacks More Lucrative Than Ever

For many years and until quite recently, credit card data stolen from online merchants has been worth far less in the cybercrime underground than cards pilfered from hacked brick-and-mortar stores. But new data suggests that over the past year, the economics of supply-and-demand have helped to double the average price fetched by card-not-present data, meaning cybercrooks now have far more incentive than ever to target e-commerce stores.

Traditionally, the average price for card data nabbed from online retailers — referred to in the underground as “CVVs” — has ranged somewhere between $2 and $8 per account. CVVs are are almost exclusively purchased by criminals looking to make unauthorized purchases at online stores, a form of thievery known as “card not present” fraud.

In contrast, the value of “dumps” — hacker slang for card data swiped from compromised retail stores, hotels and restaurants with the help of malware installed on point-of-sale systems — has long hovered around $15-$20 per card. Dumps allow street thieves to create physical clones of debit and credit cards, which are then used to perpetrate so-called “card present” fraud at brick and mortar stores.

But according to Gemini Advisory, a New York-based company that works with financial institutions to monitor dozens of underground markets trafficking in both types of data, over the past year the demand for CVVs has far outstripped supply, bringing prices for both CVVs and dumps roughly in line with each other.

Median price of card not present (CNP) vs. card-present (CP) over the past year. Image: Gemini

Stas Alforov, director of research and development at Gemini, says his company is currently monitoring most underground stores that peddle stolen card data — including such heavy hitters as Joker’s Stash, Trump’s Dumps, and BriansDump.

Contrary to popular belief, when these shops sell a CVV or dump, that record is then removed from the inventory of items for sale, allowing companies that track such activity to determine roughly how many new cards are put up for sale and how many have sold. Underground markets that do otherwise quickly earn a reputation among criminals for selling unreliable card data and are soon forced out of business.

“We can see in pretty much real-time what’s being sold and which marketplaces are the most active or have the highest number of records and where the bad guys shop the most,” Alforov said. “The biggest trend we’ve seen recently is there appears to be a much greater demand than there is supply of card not present data being uploaded to these markets.”

Alforov said dumps are still way ahead in terms of the overall number of compromised records for sale. For example, over the past year Gemini has seen some 66 million new dumps show up on underground markets, and roughly half as many CVVs.

“The demand for card not present data remains strong while the supply is not as great as the bad guys need it to be, which means prices have been steadily going up,” Alforov said. “A lot of the bad guys who used to do card present fraud are now shifting to card-not-present fraud.”

One likely reason for that shift is the United States is the last of the G20 nations to make the transition to more secure chip-based payment cards, which is slowly making it more difficult and expensive for thieves to turn dumps into cold hard cash. This same increase in card-not-present fraud has occurred in virtually every other country that long ago made the chip card transition, including AustraliaCanadaFrance and the United Kingdom.

The increasing value of CVV data may help explain why we’ve seen such a huge uptick over the past year in e-commerce sites getting hacked. In a typical online retailer intrusion, the attackers will use vulnerabilities in content management systems, shopping cart software, or third-party hosted scripts to upload malicious code that snarfs customer payment details directly from the site before it can be encrypted and sent to card processors. Continue reading →