Entries Tagged "credit cards"

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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

New Credit Card Scam

A criminal ring was arrested in Malaysia for credit card fraud:

They would visit the online shopping websites and purchase all their items using phony credit card details while the debugging app was activated.

The app would fetch the transaction data from the bank to the online shopping website, and trick the website into believing that the transaction was approved, when in reality, it had been declined by the bank.

The syndicates would later sell the items they had purchased illegally for a much lower price.

The problem here seems to be bad systems design. Why should the user be able to spoof the merchant’s verification protocol with the bank?

Posted on May 11, 2016 at 6:34 AMView Comments

Forced Authorization Attacks Against Chip-and-Pin Credit Card Terminals

Clever:

The way forced authorisation fraud works is that the retailer sets up the terminal for a transaction by inserting the customer’s card and entering the amount, then hands the terminal over to the customer so they can type in the PIN. But the criminal has used a stolen or counterfeit card, and due to the high value of the transaction the terminal performs a “referral” — asking the retailer to call the bank to perform additional checks such as the customer answering a security question. If the security checks pass, the bank will give the retailer an authorisation code to enter into the terminal.

The problem is that when the terminal asks for these security checks, it’s still in the hands of the criminal, and it’s the criminal that follows the steps that the retailer should have. Since there’s no phone conversation with the bank, the criminal doesn’t know the correct authorisation code. But what surprises retailers is that the criminal can type in anything at this stage and the transaction will go through. The criminal might also be able to bypass other security features, for example they could override the checking of the PIN by following the steps the retailer would if the customer has forgotten the PIN.

By the time the terminal is passed back to the retailer, it looks like the transaction was completed successfully. The receipt will differ only very subtly from that of a normal transaction, if at all. The criminal walks off with the goods and it’s only at the end of the day that the authorisation code is checked by the bank. By that time, the criminal is long gone. Because some of the security checks the bank asked for weren’t completed, the retailer doesn’t get the money.

Posted on December 7, 2015 at 5:35 AMView Comments

Analyzing Reshipping Mule Scams

Interesting paper: “Drops for Stuff: An Analysis of Reshipping Mule Scams. From a blog post:

A cybercriminal (called operator) recruits unsuspecting citizens with the promise of a rewarding work-from-home job. This job involves receiving packages at home and having to re-ship them to a different address, provided by the operator. By accepting the job, people unknowingly become part of a criminal operation: the packages that they receive at their home contain stolen goods, and the shipping destinations are often overseas, typically in Russia. These shipping agents are commonly known as reshipping mules (or drops for stuff in the underground community).

[…]

Studying the management of the mules lead us to some surprising findings. When applying for the job, people are usually required to send the operator copies of their ID cards and passport. After they are hired, mules are promised to be paid at the end of their first month of employment. However, from our data it is clear that mules are usually never paid. After their first month expires, they are never contacted back by the operator, who just moves on and hires new mules. In other words, the mules become victims of this scam themselves, by never seeing a penny. Moreover, because they sent copies of their documents to the criminals, mules can potentially become victims of identity theft.

Posted on November 4, 2015 at 1:54 PMView Comments

iPhone Payment Security

Apple is including some sort of automatic credit card payment system with the iPhone 6. It’s using some security feature of the phone and system to negotiate a cheaper transaction fee.

Basically, there are two kinds of credit card transactions: card-present, and card-not-present. The former is cheaper because there’s less risk of fraud. The article says that Apple has negotiated the card-present rate for its iPhone payment system, even though the card is not present. Presumably, this is because of some other security features that reduce the risk of fraud.

Not a lot of detail here, but interesting nonetheless.

Posted on September 8, 2014 at 7:21 AMView Comments

Over a Billion Passwords Stolen?

I’ve been doing way too many media interviews over this weird New York Times story that a Russian criminal gang has stolen over 1.2 billion passwords.

As expected, the hype is pretty high over this. But from the beginning, the story didn’t make sense to me. There are obvious details missing: are the passwords in plaintext or encrypted, what sites are they for, how did they end up with a single criminal gang? The Milwaukee company that pushed this story, Hold Security, isn’t a company that I had ever heard of before. (I was with Howard Schmidt when I first heard this story. He lives in Wisconsin, and he had never heard of the company before, either.) The New York Times writes that “a security expert not affiliated with Hold Security analyzed the database of stolen credentials and confirmed it was authentic,” but we’re not given any details. This felt more like a PR story from the company than anything real.

Yesterday, Forbes wrote that Hold Security is charging people $120 to tell them if they’re in the stolen-password database:

“In addition to continuous monitoring, we will also check to see if your company has been a victim of the latest CyberVor breach,” says the site’s description of the service using its pet name for the most recent breach. “The service starts from as low as 120$/month and comes with a 2-week money back guarantee, unless we provide any data right away.”

Shortly after Wall Street Journal reporter Danny Yadron linked to the page on Twitter and asked questions about it, the firm replaced the description of the service with a “coming soon” message.

Holden says by email that the service will actually be $10/month and $120/year. “We are charging this symbolical fee to recover our expense to verify the domain or website ownership,” he says by email. “While we do not anticipate any fraud, we need to be cognizant of its potential. The other thing to consider, the cost that our company must undertake to proactively reach out to a company to identify the right individual(s) to inform of a breach, prove to them that we are the ‘good guys’. Believe it or not, it is a hard and often thankless task.”

This story is getting squirrelier and squirrelier. Yes, security companies love to hype the threat to sell their products and services. But this goes further: single-handedly trying to create a panic, and then profiting off that panic.

I don’t know how much of this story is true, but what I was saying to reporters over the past two days is that it’s evidence of how secure the Internet actually is. We’re not seeing massive fraud or theft. We’re not seeing massive account hijacking. A gang of Russian hackers has 1.2 billion passwords — they’ve probably had most of them for a year or more — and everything is still working normally. This sort of thing is pretty much universally true. You probably have a credit card in your wallet right now whose number has been stolen. There are zero-day vulnerabilities being discovered right now that can be used to hack your computer. Security is terrible everywhere, and it it’s all okay. This is a weird paradox that we’re used to by now.

Oh, and if you want to change your passwords, here’s my advice.

EDITED TO ADD (8/7): Brian Krebs vouches for Hold Security. On the other hand, it had no web presence until this story hit. Despite Krebs, I’m skeptical.

EDITED TO ADD (8/7): Here’s an article about Hold Security from February with suspiciously similar numbers.

EDITED TO ADD (8/9): Another skeptical take.

Posted on August 7, 2014 at 7:45 AMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.