Entries Tagged "credit cards"

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Interesting Attack on the EMV Smartcard Payment Standard

It’s complicated, but it’s basically a man-in-the-middle attack that involves two smartphones. The first phone reads the actual smartcard, and then forwards the required information to a second phone. That second phone actually conducts the transaction on the POS terminal. That second phone is able to convince the POS terminal to conduct the transaction without requiring the normally required PIN.

From a news article:

The researchers were able to demonstrate that it is possible to exploit the vulnerability in practice, although it is a fairly complex process. They first developed an Android app and installed it on two NFC-enabled mobile phones. This allowed the two devices to read data from the credit card chip and exchange information with payment terminals. Incidentally, the researchers did not have to bypass any special security features in the Android operating system to install the app.

To obtain unauthorized funds from a third-party credit card, the first mobile phone is used to scan the necessary data from the credit card and transfer it to the second phone. The second phone is then used to simultaneously debit the amount at the checkout, as many cardholders do nowadays. As the app declares that the customer is the authorized user of the credit card, the vendor does not realize that the transaction is fraudulent. The crucial factor is that the app outsmarts the card’s security system. Although the amount is over the limit and requires PIN verification, no code is requested.

The paper: “The EMV Standard: Break, Fix, Verify.”

Abstract: EMV is the international protocol standard for smartcard payment and is used in over 9 billion cards worldwide. Despite the standard’s advertised security, various issues have been previously uncovered, deriving from logical flaws that are hard to spot in EMV’s lengthy and complex specification, running over 2,000 pages.

We formalize a comprehensive symbolic model of EMV in Tamarin, a state-of-the-art protocol verifier. Our model is the first that supports a fine-grained analysis of all relevant security guarantees that EMV is intended to offer. We use our model to automatically identify flaws that lead to two critical attacks: one that defrauds the cardholder and another that defrauds the merchant. First, criminals can use a victim’s Visa contact-less card for high-value purchases, without knowledge of the card’s PIN. We built a proof-of-concept Android application and successfully demonstrated this attack on real-world payment terminals. Second, criminals can trick the terminal into accepting an unauthentic offline transaction, which the issuing bank should later decline, after the criminal has walked away with the goods. This attack is possible for implementations following the standard, although we did not test it on actual terminals for ethical reasons. Finally, we propose and verify improvements to the standard that prevent these attacks, as well as any other attacks that violate the considered security properties.The proposed improvements can be easily implemented in the terminals and do not affect the cards in circulation.

Posted on September 14, 2020 at 6:21 AMView Comments

Detecting Credit Card Skimmers

Modern credit card skimmers hidden in self-service gas pumps communicate via Bluetooth. There’s now an app that can detect them:

The team from the University of California San Diego, who worked with other computer scientists from the University of Illinois, developed an app called Bluetana which not only scans and detects Bluetooth signals, but can actually differentiate those coming from legitimate devices — like sensors, smartphones, or vehicle tracking hardware — from card skimmers that are using the wireless protocol as a way to harvest stolen data. The full details of what criteria Bluetana uses to differentiate the two isn’t being made public, but its algorithm takes into account metrics like signal strength and other telltale markers that were pulled from data based on scans made at 1,185 gas stations across six different states.

Posted on August 26, 2019 at 6:41 AMView Comments

Using Gmail "Dot Addresses" to Commit Fraud

In Gmail addresses, the dots don’t matter. The account “bruceschneier@gmail.com” maps to the exact same address as “bruce.schneier@gmail.com” and “b.r.u.c.e.schneier@gmail.com” — and so on. (Note: I own none of those addresses, if they are actually valid.)

This fact can be used to commit fraud:

Recently, we observed a group of BEC actors make extensive use of Gmail dot accounts to commit a large and diverse amount of fraud. Since early 2018, this group has used this fairly simple tactic to facilitate the following fraudulent activities:

  • Submit 48 credit card applications at four US-based financial institutions, resulting in the approval of at least $65,000 in fraudulent credit
  • Register for 14 trial accounts with a commercial sales leads service to collect targeting data for BEC attacks
  • File 13 fraudulent tax returns with an online tax filing service
  • Submit 12 change of address requests with the US Postal Service
  • Submit 11 fraudulent Social Security benefit applications
  • Apply for unemployment benefits under nine identities in a large US state
  • Submit applications for FEMA disaster assistance under three identities

In each case, the scammers created multiple accounts on each website within a short period of time, modifying the placement of periods in the email address for each account. Each of these accounts is associated with a different stolen identity, but all email from these services are received by the same Gmail account. Thus, the group is able to centralize and organize their fraudulent activity around a small set of email accounts, thereby increasing productivity and making it easier to continue their fraudulent behavior.

This isn’t a new trick. It has been previously documented as a way to trick Netflix users.

News article.

Slashdot thread.

Posted on February 6, 2019 at 10:24 AMView Comments

Chip Cards Fail to Reduce Credit Card Fraud in the US

A new study finds that credit card fraud has not declined since the introduction of chip cards in the US. The majority of stolen card information comes from hacked point-of-sale terminals.

The reasons seem to be twofold. One, the US uses chip-and-signature instead of chip-and-PIN, obviating the most critical security benefit of the chip. And two, US merchants still accept magnetic stripe cards, meaning that thieves can steal credentials from a chip card and create a working cloned mag stripe card.

Boing Boing post.

Posted on November 15, 2018 at 6:24 AMView Comments

Detecting Credit Card Skimmers

Interesting research paper: “Fear the Reaper: Characterization and Fast Detection of Card Skimmers“:

Abstract: Payment card fraud results in billions of dollars in losses annually. Adversaries increasingly acquire card data using skimmers, which are attached to legitimate payment devices including point of sale terminals, gas pumps, and ATMs. Detecting such devices can be difficult, and while many experts offer advice in doing so, there exists no large-scale characterization of skimmer technology to support such defenses. In this paper, we perform the first such study based on skimmers recovered by the NYPD’s Financial Crimes Task Force over a 16 month period. After systematizing these devices, we develop the Skim Reaper, a detector which takes advantage of the physical properties and constraints necessary for many skimmers to steal card data. Our analysis shows the Skim Reaper effectively detects 100% of devices supplied by the NYPD. In so doing, we provide the first robust and portable mechanism for detecting card skimmers.

Boing Boing post.

Posted on October 5, 2018 at 6:44 AMView Comments

Airline Ticket Fraud

New research: “Leaving on a jet plane: the trade in fraudulently obtained airline tickets:”

Abstract: Every day, hundreds of people fly on airline tickets that have been obtained fraudulently. This crime script analysis provides an overview of the trade in these tickets, drawing on interviews with industry and law enforcement, and an analysis of an online blackmarket. Tickets are purchased by complicit travellers or resellers from the online blackmarket. Victim travellers obtain tickets from fake travel agencies or malicious insiders. Compromised credit cards used to be the main method to purchase tickets illegitimately. However, as fraud detection systems improved, offenders displaced to other methods, including compromised loyalty point accounts, phishing, and compromised business accounts. In addition to complicit and victim travellers, fraudulently obtained tickets are used for transporting mules, and for trafficking and smuggling. This research details current prevention approaches, and identifies additional interventions, aimed at the act, the actor, and the marketplace.

Blog post.

Posted on May 11, 2018 at 6:24 AMView Comments

Guessing Credit Card Security Details

Researchers have found that they can guess various credit-card-number security details by spreading their guesses around multiple websites so as not to trigger any alarms.

From a news article:

Mohammed Ali, a PhD student at the university’s School of Computing Science, said: “This sort of attack exploits two weaknesses that on their own are not too severe but when used together, present a serious risk to the whole payment system.

“Firstly, the current online payment system does not detect multiple invalid payment requests from different websites.

“This allows unlimited guesses on each card data field, using up to the allowed number of attempts — typically 10 or 20 guesses — on each website.

“Secondly, different websites ask for different variations in the card data fields to validate an online purchase. This means it’s quite easy to build up the information and piece it together like a jigsaw.

“The unlimited guesses, when combined with the variations in the payment data fields make it frighteningly easy for attackers to generate all the card details one field at a time.

“Each generated card field can be used in succession to generate the next field and so on. If the hits are spread across enough websites then a positive response to each question can be received within two seconds — just like any online payment.

“So even starting with no details at all other than the first six digits — which tell you the bank and card type and so are the same for every card from a single provider — a hacker can obtain the three essential pieces of information to make an online purchase within as little as six seconds.”

That’s card number, expiration date, and CVV code.

From the paper:

Abstract: This article provides an extensive study of the current practice of online payment using credit and debit cards, and the intrinsic security challenges caused by the differences in how payment sites operate. We investigated the Alexa top-400 online merchants’ payment sites, and realised that the current landscape facilitates a distributed guessing attack. This attack subverts the payment functionality from its intended purpose of validating card details, into helping the attackers to generate all security data fields required to make online transactions. We will show that this attack would not be practical if all payment sites performed the same security checks. As part of our responsible disclosure measure, we notified a selection of payment sites about our findings, and we report on their responses. We will discuss potential solutions to the problem and the practical difficulty to implement these, given the varying technical and business concerns of the involved parties.

BoingBoing post:

The researchers believe this method has already been used in the wild, as part of a spectacular hack against Tesco bank last month.

MasterCard is immune to this hack because they detect the guesses, even though they’re distributed across multiple websites. Visa is not.

Posted on December 5, 2016 at 6:25 AMView Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.