Hacking Point of Sale: Payment Application Secrets, Threats, and Solutions

The only negative thing to say about Hacking Point of Sale: Payment Application Secrets, Threats, and Solutions is its title.  A cursory look at it may lead the reader that this is a book for a script kiddie, when it is in fact a necessary read for anyone involved with payment systems.  The book provides a wealth of information that is completely pragmatic and actionable.  The problem is, as the book notes in many places, that one is constantly patching a system that is inherently flawed and broken.

Often after a major information security breach incidents, a public official (always in front of cameras and with many serious looking people standing in the wings) will go on TV and say something akin to “we have to make sure this never happens again”. 

Last year, Target and Neiman Marcus were the major victims.  This month, it’s eBay.  What next month will bring isn’t known, but it will be major.  But after hundreds of millions of records breached, it’s not that anyone is saying it won’t happen again.  Rather, it’s inevitable it will happen many more times.

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There are a number of good books on PCI, but this is the first one that looks at the entire spectrum of credit card processing.  Author Slava Gomzin is a security and payments technologist at HP and as clearly evident in the book, he lives and breathes payment technology and his expert knowledge is manifest in every chapter.  His technical expertise is certain to make the reader much better informed and understand the myriad issues involved.

The book provides an excellent overview to the workings of payment systems and Gomzin is not shy about showing how insecure many payment systems are. Its 9 chapters provide a good combination of deep technical and general detail.

The reader comes out with a very good overview of how payment systems work and what the various parts of it are.  For many people, this may be the first time they are made aware of entities such as processors, acquirers and gateways.

An interesting point the book raises is that it has been observed there are less breaches in Europe since they use EMV (also known as chip and pin) instead of insecure magnetic-stripe cards which are used in the US.  This leads to a perception that EMV is by default much stronger.  But the book notes that EMV was never designed to secure the cardholder data after the point of sale.  The recent breaches at Target and Neiman Marcus were such that cardholder data was pilfered after it was in the system.

Another major weakness with EMV is it doesn't provide added security to web and online transactions. When a customer goes to a site and makes a transaction with an EMV card, it is fundamentally the same as if they would have used a magnetic stripe card.  What many people don’t realize also is that EMV is not some new technology. It’s been around for a while.  What it did was reduce the amount of fraud for physical use amongst European merchants.  But the unintended consequence was that it simply moved the fraud online, where EMV is powerless.

As noted, the book provides the details and vulnerabilities of every aspect of the life of a payment card, including physical security.  In chapter 4, he notes that there are numerous features that are supposed to distinguish between a genuine payment card from a counterfeited one.  These include logo, embossed primary account number (PAN), card verification values and ultraviolet (UV) marks.  Each one of them has their own set of limits.  For the supposed security of UV marks, these are relatively easily replicated by a regular inkjet printer with UV ink.

In fact, Gomzin writes that all payment cards as they are in use today are insecure by design due to the fact that there are multiple physical security features that don’t provide adequate protection from theft, and that the sensitive cardholder data information is encoded on a magnetic strip in clear text.

Gomzin has numerous PCI certifications and with all that, doesn’t see PCI as the boon to payment card security as many do.  He astutely observes that PCI places a somewhat myopic approach that data at rest is all that matters.  Given that PCI doesn’t require payment software vendors or users to encrypt application configuration data, which is usually stored in plaintext and opened to uncontrolled modification; this can allow payment application to be compromised through misconfiguration.

Even with PCI, Gomzin shows that credit card numbers are rather predictable in that their number space is in truth rather small, even though they may be 15-19 digits in length.  This is due to the fact that PCI allows the first 6 and last 4 digits to be exposed in plaintext, so it’s only 6 digits that need to be guessed.  This enables a relatively easy brute force attack, and even easier if rainbow tables are used.

The Target breach was attributed to memory scraping and the book notes that as devastating an attack memory scraping is, there are no existing reliable security mechanisms that would prevent memory scraping.

The appendix includes a POS vulnerability rank calculator which can provide a quick and dirty risk assessment of the POS and associated payments application and hardware.  The 20 questions in the calculator can’t replace a formal assessment.  But the initial results would likely mimic what that formal assessment would enumerate.

So what will it take to fix the mess that POS and payment systems are in now?  The book notes that the system has to be completely overhauled for POS security to truly work.  He notes that point-to-point encryption is one of the best ways to do that.  What is stopping that is the huge costs involved in redoing the payment infrastructure.  But until then, breaches will be daily news.

Hacking Point of Sale: Payment Application Secrets, Threats, and Solutions is an invaluable resource that it highly relevant to a wide audience.  Be it those in compliance, information security, development, research or in your payment security group.  If you are involved with payment systems, this is a necessary book.

When an expert like Slava Gomzin writes, his words should be listened to.  He knows that payment breaches are inevitable.  But he also shows you how to potentially avoid that tidal wave of inevitability.

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