Weblogic Authors: Yeshim Deniz, Elizabeth White, Michael Meiner, Michael Bushong, Avi Rosenthal

Blog Feed Post

Controls are still an issue for the PCI Tokenization Guidelines

The PCI Council today released the long-awaited tokenization guidelines (Information Supplement: PCI Tokenization Guidelines) which give merchants specific guidance on using tokenization to reduce PCI scope and assessment costs, which have been costing large merchants upwards of $500,000 / year.

While the guidance is strong, it seems to provide one area of ambiguity around controls for so called high-value tokens which we will examine in some depth later in this blog. First, let’s dig into the guidance itself:

Out of Scope Considerations

The main thrust of the guidance defines a scoping principle and then out-of-scope considerations. The scoping principles state that all components of the tokenization system are considered part of the cardholder data envrionment (CDE). The scoping principles refine this further to include the token generation and detokenization components as well as any system with access to the tokenization system or part of the CDE.

For specific out-of-scope considerations, the document states the following requirements. I thought it would be helpful to analyze the guidelines in terms of a real-world use case: credit card information stored in a data-warehouse application used for post-payment customer loyalty tracking. Let’s assume that our fictional merchant has decided to receive new entries as format-preserving tokens using Intel(R) Expressway Tokenization Broker (ETB). In this example, the gateway is the tokenization engine and is the only entity with access to a secure token vault. We can assume that the data-warehouse application has no need for the live PANs and if PAN data is required for charge-back or refunds, it is retrieved by a different application (which would be in full PCI scope).

  1. Recovery of the PAN value associated with a token must not be computationally feasible through knowledge of only the token, multiple tokens, or other token-to-PAN combinations.
  2. ETB generates format-preserving tokens based on true random numbers or pseudo-random numbers with a protected seed. This means that there is no mathematical relation between the token and the PAN. This requirement appears to be met. It is interesting to note here that the guidance would technically allow a token generated from the PAN through an encryption or hash function to count, but the burden would be to show that this transformation is computationally infeasible to reverse

  3. PAN cannot be retrieved even if the token and the systems it resides on are compromised
  4. Expressway Tokenization Broker (ETB) stores PAN values encrypted in the secure token vault using AES-256. Even if the vault were compromised, the attacker would have to execute a brute-force attack against AES-256. The same goes with the data-warehouse application as only tokens would be available. Gaining access to only the token list would provide no value as well as there is no mathematical relation between the two. Note that again, this may not be the case when the token is generated using an encryption or hash function.

  5. System components are segmented (isolated) from any application, system, process, or user with: (i) The ability to submit a de-tokenization request for that token and retrieve the PAN, (ii) Access to the tokenization system, data vault, or cryptographic keys for that token, (iii) Access to token input data or other information that can be used to de-tokenize or derive the PAN value from the token
  6. ETB supports both the proper segmentation and access control. In our example, the broker would be sending tokens to the data-warehouse application rather than live PANs and would be segmented by at least one network hop. Further, the broker would not provide de-tokenization access to the data-warehouse application using a specific security policy. The broker itself is also segmented from the secure vault and only the broker can access the vault using 2-way protected TLS communication. Further, an external identity store such as LDAP, Active Directory, Siteminder, Oracle Access Manager, IBM Tivoli Access Manager and others can be used to authenticate de-tokenization requests. A requesting application can approach the broker through an authenticated REST or SOAP API call to retrieve a token or provide an entire document or message to be tokenized.

  7. System components are not connected to the tokenization system or processes, including the data vault, or cryptographic key storage
  8. Here, the system component (data-warehouse application) would only have the ability to receive tokens from ETB and would not be connected to the tokenization or de-tokenization process and would not have access to the vault or cryptogrpahic key storage. It is an open question if this ability to receive only tokens will be classified as connectedness.

  9. System components do not store, process, or transmit cardholder data or sensitive authentication data through any other channel
  10. This item would be met by our example as the data-warehouse application would only be receiving format-preserving tokens.

  11. System components that previously stored, processed, or transmitted cardholder data prior to implementation of the tokenization solution have been examined to ensure that all traces of cardholder data have been securely deleted.

  12. This is more of a process issue. It makes sense that before our data-warehouse application can be taken out of scope, the existing PAN data must be thoroughly scrubbed out

It seems that the key issue turns on network connectedness. In other words, if by virtue of network connection only, if the data warehouse application is still in scope even though it is (a) receiving only tokens, and (b) has no access to exchange tokens for PANs, then a QSA should be able to make this distinction without a full review of the data-warehouse application and all of its connected components.

High-Value Tokens

Section four of the PCI Tokenization guidelines poses an interesting question regarding high value tokens. Just what is a high-value token? Here, they are referring to tokens that can be used to generate transactions. While they are not themselves PAN values, they can be used as a true surrogate for the PAN. The intuitive example given is the use of a room number in paying for a meal at a hotel restaurant. In this example, the token (the room number) along with a last name (ostensibly a secret) generates a transaction for a credit card. Under this view, the PCI council seems to be suggesting that a list of compromised last names and room numbers falls under PCI DSS! In other words, if tokens begin to look like and act like PANs, they bear the same compliance burden PANs. This seems like overstretching and more clarity is needed.

Fortunately, the guidelines give an additional caveat, which is the the key phrase, “additional controls” , and this is where more guidance is needed. In other words, the loss or compromise of a token doesn’t expose anything, as long as you have the proper controls. What could these controls look like? It seems reasonable that tokens that work just like PANs – let’s called them uncontrolled high value tokens – definitely contribute to the risk of a breach. Here is a stab at some types of controls for high value tokens that generate transactions.

High Value Token Controls

  • Single-Use: Should be single-use where one token maps to a different PAN each time. This may reduce the risk of an attacker collecting tokens for a concentrated attack in the future

  • Short Lifetime: Should be given a constrained lifetime for additional protection
  • Authentication: Should only generate a transaction in connection with additional protected authentication data that defines the entity attempting to make the transaction (person or system)
  • Authorization: Is only authorized for a specific transaction and not others.
  • Unpredictability : Valid tokens should not be predictable. In other words, an attacker should not be able to anticipate valid token values

The previous list is just a stab. It will be interesting to see what sort of specific guidance emerges in the future.


Read the original blog entry...

More Stories By Application Security

This blog references our expert posts on application and web services security.

@ThingsExpo Stories
DX World EXPO, LLC, a Lighthouse Point, Florida-based startup trade show producer and the creator of "DXWorldEXPO® - Digital Transformation Conference & Expo" has announced its executive management team. The team is headed by Levent Selamoglu, who has been named CEO. "Now is the time for a truly global DX event, to bring together the leading minds from the technology world in a conversation about Digital Transformation," he said in making the announcement.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that Conference Guru has been named “Media Sponsor” of the 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. A valuable conference experience generates new contacts, sales leads, potential strategic partners and potential investors; helps gather competitive intelligence and even provides inspiration for new products and services. Conference Guru works with conference organizers to pass great deals to gre...
The Internet of Things will challenge the status quo of how IT and development organizations operate. Or will it? Certainly the fog layer of IoT requires special insights about data ontology, security and transactional integrity. But the developmental challenges are the same: People, Process and Platform. In his session at @ThingsExpo, Craig Sproule, CEO of Metavine, demonstrated how to move beyond today's coding paradigm and shared the must-have mindsets for removing complexity from the develop...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
"Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.