Archive Page 2

10
Apr
17

MFA – It Is All In The Implementation

I have been challenged over the last few weeks over requirement 8.3.1 along with the implications of the Council’s latest Information Supplement on multi-factor authentication (MFA).  Requirement 8.3.1 does not go into effect until February 1, 2018, but there are a lot of organizations trying to get a jump on it.  As a result I am hearing from QSAS that they are getting more and more questions and scenarios to see if they are PCI compliant.

As a reminder, requirement 8.3.1 states:

“Incorporate multi-factor authentication for all non-console access into the CDE for personnel with administrative access.”

The most common and biggest challenge has come from organizations that have implemented MFA across their entire network and therefore believe that they are automatically in compliance with 8.3.1.

Not so fast.  The guidance for 8.3.1 states:

“If the CDE is segmented from the rest of the entity’s network, an administrator would need to use multi-factor authentication when connecting to a CDE system from a non-CDE network. Multi-factor authentication can be implemented at network level or at system/application level; it does not have to be both. If the administrator uses MFA when logging into the CDE network, they do not also need to use MFA to log into a particular system or application within the CDE.”

According to this guidance, it is the cardholder data environment (CDE) that is the border for the MFA, not the network as a whole.  So while an organization might have implemented MFA as part of their general security, having MFA for the entire network does not meet the requirement of 8.3.1.

We need to remember what drove the development of requirement 8.3.1 was a lesson learned from the Target and similar breaches.  In all of these breaches, system administrators were spear phished allowing the attackers to access the CDE in one way or another.  Requirement 8.3.1 minimizes this threat by requiring MFA to gain access to the CDE.  So even if an attacker obtains an administrator’s credentials or compromises an administrator’s system, that fact in and of itself would not compromise the CDE.

This is why the guidance for 8.3.1 puts the MFA border at the CDE.  If you have MFA implemented in order to gain access to your network, how does that stop the threat of phishing?  It does not.  A spear phishing attack against such an MFA implementation defeats the MFA because it has already been applied.  The MFA in this scenario does not stop access to the CDE.

But keep in mind, MFA only minimizes the risk to administrators.  You still need to be vigilant in ensuring that administrator systems remain secure and free of viruses and malware.  As such, it is not unusual to find that organizations are taking more active approaches to securing administrator systems including adding other technologies such as file integrity monitoring, white listing and/or black listing in addition to anti-virus.

But it is not just administrators you need to worry about.  Anyone that has access to bulk cardholder data (CHD) that is stored is also at risk.  As a result, we are starting to see organizations also requiring these users to use MFA to access the CDE as well as having their systems implement enhanced security to ensure they remain uncompromised.

Just some things to think about as you got through your MFA discussions.

02
Apr
17

Business Continuity And PCI

This topic came up this past week in a conversation.  I had to go to the PCI DSS v3.2 and check to make sure what was being discussed was accurate.  The discussion was around requirement 12.10.1 which says:

“Create the incident response plan to be implemented in the event of system breach. Ensure the plan addresses the following, at a minimum:

  • Roles, responsibilities, and communication and contact strategies in the event of a compromise including notification of the payment brands, at a minimum

  • Specific incident response procedures

  • Business recovery and continuity procedures

  • Data backup processes

  • Analysis of legal requirements for reporting compromises

  • Coverage and responses of all critical system components

  • Reference or inclusion of incident response procedures from the payment brands.”

The points of the discussion focused on the third and fourth bullets.  Yes, that is right, they are calling out business recovery and continuity procedures and data backup processes.  This caught me a bit flat footed at first.

For those of you that have been involved in or around PCI for a while are probably scratching your heads because the PCI DSS has never truly cared about business continuity unless it was a hot failover solution.  The Council has even said so much at various Community Meetings over the years when business continuity and disaster recovery have come up as question topics.

So, what is the deal?

Well, the guidance provided for 12.10.1 sure does not give you a clue as it only says:

“The incident response plan should be thorough and contain all the key elements to allow your company to respond effectively in the event of a breach that could impact cardholder data.”

And the Report On Compliance (ROC) is still only asking for the name of the QSA that will attest to the incident response plan including these items.

Is the PCI DSS now interested in business continuity?

As I said earlier, the PCI DSS was to a degree interested in business continuity if it was always active as with a hot failover scenario and they have always been concerned about data backup processes as witnessed by requirements 9.5, 9.6, 9.7 and 9.8.  The more we discussed these topics the more we believe that the PCI DSS is looking for organizations to ensure continuity of their PCI compliance when they invoke their business continuity plan.

The PCI DSS has only included business continuity (aka disaster recovery) in scope if cardholder data (CHD) is actively involved.  This happens when organizations have hot recovery capabilities in their disaster recovery data center or are replicating data (that includes CHD) in real time to a disaster recovery site.  Otherwise, the disaster recovery site is not in scope for the PCI assessment.  As a result, most organizations push back on including their disaster recovery sites in their PCI assessments if they are cold or warm sites with no CHD involved.

However, here is the rub with that approach.  Under the PCI DSS and the card brand agreements, the moment that any disaster recovery site becomes active because of a disaster, it is required to be PCI compliant.  There is no grace period.  None.

So, if a disaster recovery site has never been assessed for PCI compliance, how does an organization know it will be compliant?  They do not.  There could be significant PCI compliance issues not just with the site, but with the emergency business processes as well.  That is why smart organizations periodically assess their disaster recovery sites and processes for PCI compliance so that there are few, if any, PCI compliance surprises when they activate them.

While the PCI DSS is not asking for an assessment of business continuity and data backup processes, the PCI DSS is providing a friendly reminder to organizations that business continuity can become a compliance problem and should be looked at before it creates an issue.

24
Mar
17

Service Provider AOCs and Section 2g

It is becoming obvious that there are a lot of QSAs out there did not get the message when v3 of the PCI DSS came out and the new AOC for service providers was introduced.  This has been a big topic at the last few community meetings as well and recently became a big topic with a number of my clients as I continue to see service provider AOCs that are not correct.  I have even mentioned this problem already in a post about service providers, but the problem continues.

As a result, I have decided this is a great time to discuss the problem and get everyone to ensure it is fixed so that we stop the arguments over something that is clearly documented in the service provider AOC form and needs to be done correctly.  Because there is no excuse for messing this up.

Section 2a

Before we get to the actual problem, we need to talk about section 2a in the service provider AOC as it drives the problem.

PCI AOC SP Section 2a

In section 2a of the service provider AOC, a QSA is call out in the ‘Name of service(s) assessed’ and to check every box in the ‘Type of Service(s) assessed’ for every service named as part of the service provider’s PCI assessment.

QSAs seem to be doing very well in checking the appropriate boxes for ‘Type of Service(s) assessed’ on the AOCs that I encounter.  However for the ‘Name of service(s) not assessed’, QSAs seem to not necessarily doing quite as well.  The reason will become obvious when I discuss section 2g.

One important note though.  When checking the ‘Others’ box (or any of the ‘Other’ boxes), please make sure to list ALL the other services that were assessed and NEVER, EVER use “etc” in that explanation.  All the services in the ‘Others’ category MUST BE listed individually and specifically.  Again, this will become obvious as to why when we get to section 2g.

And before we move on, I get questions about cloud services, i.e., SaaS, PaaS and IaaS.  Those are services and should be listed as such in the ‘Name of service(s) assessed’.

Section 2g

PCI AOC SP Section 2g

Notice that shaded ‘Note’ that is in bold and italics that states:

“One table to be completed for each service covered by this AOC. Additional copies of this section are available on the PCI SSC website.”

What this note means is you need to have the same number of section 2g’s as you have named services in section 2a.  And this is where a lot of QSAs and their QA reviewers are going wrong with their service provider AOCs

For example, if you have named five services in 2a, there had better be five pages of 2g filled out.  One for each of those five named services.  By the same token, if you are relying on check boxes under the ‘Type of Service(s) assessed’ section to define the services covered, then you should call those out separately in 2g.

The bottom line though is that, however a QSA breaks things out, there must be multiple 2g sections for each individual service provided.

In some very rare instances there can be some services that might have the same coverages/responsibilities for the requirements in the matrix and those may be combined into one table.  The Council has even said as much in clarifying this form.  However the Council has also been very clear that when combining those services into one 2g section, those services MUST have EXACTLY the same responsibilities and that is where a lot of QSAs get into trouble.  So the recommendation I would make is just do one 2g for every service and stop trying to combine things.

Now the QSAs that I have had discussions (arguments) with over their flawed service provider AOCs always bring up the fact that the AOC Word document is locked and they cannot make changes.  I always point them back to that ‘Note’ in 2g which states:

“Additional copies of this section are available on the PCI SSC website.”

According to the guidance provided by the Council at the Community Meetings, QSAs are to append those additional 2g sections to the end of the AOC.

That said, some of us in the QSA community have unlocked the Word document (NOT approved by the Council) and just copy section 2g and insert it inline in the AOC for the number of services we need sections for and fill them out.

One final note about section 2g.  Please follow the instructions to the letter when filling out the table/matrix for the service.  I cannot tell you the number of those that I encounter where ‘Partial’ or ‘None’ are checked and then there is nothing documented in the ‘Justification’ column.  The instructions are very clear in how you are supposed to fill the ‘Justification’ column out so there is no excuse for leaving it blank.

And for the merchants that have to deal with these service provider AOCs.  It is up to you to police these documents.  If you receive an AOC and it is not properly filled out, it is up to you to point out your concerns to the service provider.  If the service provider does not address your concerns, you have a couple of options at your disposal.

  • Contact the PCI SSC with your concerns at qsa@pcisecuritystandards.org. Document your concern(s) in your email as well as including the AOC in question.
  • If the service provider is listed on either the Visa or MasterCard service provider lists on their respective Web site, you should notify them as well. This is because both of those card brands should have caught this error before listing the service provider on their Web site.  For Visa, go to http://www.visa.com/splisting/learnmore.html and use the appropriate email address for your region under the PCI DSS Validated Service Providers row.  For MasterCard, use the pcireports@mastercard.com email address and as with the Council document your concern(s) in an email as well as including the AOC in question.

By contacting the Council, you will provide the Council feedback that a QSAC is not conducting their assessments for service providers appropriately and that the Council may need to conduct an assessor quality management (AQM) process for that QSAC.

Notifying the card brands will do two things.  It will point out a potential flaw in their service provider listing process that needs to be addressed.  But it could also potentially put the service provider in a different status on the card brands’ lists.

21
Mar
17

Stripe Questions Come Back

I have had a couple of readers ask this question, so I thought it was time to go back and take a look at it again.  It has been since 2013 that I first brought up Stripe as a potential compliance scoping issue.

The question being posed is:

“How can Stripe claim on its Web site that its JavaScript checkout solution allows for a merchant to use SAQ A?”

The first thing to notice is the sidebar regarding the various Stripe solutions.  There are three distinct solutions offered by Stripe:

  • Checkout
  • Elements
  • Stripe.js (the original solution)

In the PCI DSS Guidelines section is the following:

“Elements and Checkout host all form inputs containing card data within an IFRAME served from Stripe’s domain.

As long as you serve your payment pages over TLS, and use either Checkout or Elements as the only way of handling card information, Stripe automatically creates a combined SAQ A and Attestation of Compliance (AOC) for you.”

The first important point is that, if a merchant is using the Stripe.js solution, it does NOT qualify for the SAQ A.  This is the original solution that I wrote about back in 2013.  But the fact that Stripe.js is not SAQ A eligible is an important point for all developers to note as it could easily be missed.

What has changed is Stripe has created two new methods for processing payments: Checkout and Elements.  Those methods create an iFrame that, in theory, would comply with scope minimization and allowing SAQ A to be used by the merchant.

But, this statement “As long as you serve your payment pages over TLS, and use either Checkout or Elements as the only way of handling card information …” is all in the execution by the merchant’s Web site as not all iFrames are created equal.  What a merchant and their developer must do is ensure that the iFrame is created ONLY on the customer’s PC and NOT on the merchant’s Web server.  If done that way, then the statement regarding SAQ A is accurate.

The reason I bring this fact up is that I have encountered solutions using an iFrame but where the iFrame is built on the merchant’s server and not in the customer’s browser.  The merchant points to the fact that the solution is an iFrame and therefore their Web server out of scope.  However, since the iFrame is constructed on the merchant’s Web server and then sent to the customer, it is no longer eligible for SAQ A and the merchant must follow SAQ A-EP.

As a result, it is important that a QSA look very closely at how a merchant’s Web site executes to ensure that the iFrame is never created on the merchant’s Web server.

Based on the examples of what I saw regarding the Checkout and Element solutions, as long as the code samples for Checkout or Element only execute in the customer’s browser, SAQ A would be a valid assessment option.

15
Mar
17

Why We Should Be Concerned About The Verifone Breach

On March 7 Brian Krebs broke the news that Verifone, one of the largest card terminal manufacturers, has suffered a breach. The next day Verifone told the world that the breach was no big deal. No big deal right? Probably not and here is my rationale.

For those of you unfamiliar with Verifone, Verifone is not only a manufacturer of points of interaction (POI, aka card/transaction terminals), it also provides transaction processing services to merchants. As a result, any breach of such an organization puts a lot of the security of the card processing ecosystem at tremendous risk.

Extent Of The Breach

Here is what Verifone has told us about the extent of the breach.

“According to third-party forensic teams, this cyber attempt was limited to approximately two dozen U.S. gas station convenience stores and occurred over a short time period. No other merchants were targeted and the integrity of our payment networks and Verifone’s payment terminals remained secure and fully operational.

Verifone’s information security team identified evidence of this very limited cyber intrusion into our corporate network in January 2017, and we proactively notified Visa, MasterCard and other card schemes.

In concert with our partners, Verifone immediately implemented additional security controls across its corporate networks and began work to determine the type of information that may have been targeted.

It is also worth noting that there have been no adverse events or misuse of any data resulting from this incident. Verifone, partner agencies, and law enforcement remain vigilant and will continue to monitor for this.

We believe that our immediate response and coordination with partners and agencies has made the potential for misuse of information extremely limited.”

The first thing that any forensic examiner will tell you is that determining the extent of a breach is not a trivial process. It takes time. Most times, a lot of time. The reason is that attackers can be very stealthy in how they cover their tracks by wiping logs, leave behind malware/backdoors, and other techniques to obscure what they did and how they did it.  Even though Verifone took almost two months to acknowledge the breach and tell everyone that things are fine, all may not necessarily be well within Verifone.  But only time will tell if that is true.

The troubling thing about Verifone’s statement and likely demanded by their lawyers is the wording at the very end of their statement as they start their last sentence – “We believe”. Legalese that will give them an out should their forensic teams find more issues or issues turn up later.

“Asked about the breach reports, a Verifone spokesman said the company saw evidence in January 2017 of an intrusion in a “limited portion” of its internal network, but that the breach never impacted its payment services network.”

This was followed up by an update by Mr. Krebs after his original post. Verifone stated:

“According to the forensic information to-date, the cyber attempt was limited to controllers at approximately two dozen gas stations, and occurred over a short time frame. We believe that no other merchants were targeted and the integrity of our networks and merchants’ payment terminals remain secure and fully operational.”

Hold on a moment.  What is a “short time frame”?  Oh, and by the way, the attackers had access to controllers and around two dozen gas stations?  And then there is that “According to the forensic information to-date” comment.  That statement would seem to imply that Verifone is not necessary complete with their forensic examination.

So did Verifone or someone else find this breach?

“But a source with knowledge of the matter told KrebsOnSecurity.com that the employee alert Verifone sent out on Jan, 23, 2017 was in response to a notification that Verifone received from the credit card companies Visa and Mastercard just days earlier in January.”

So like most organizations, they were notified by a third party that they likely had been breached.  In this case, two card brands recognized fraudulent transactions that came from merchants serviced by Verifone.

But follow that statement with this one regarding what happened once they were notified.

 “Verifone’s information security team identified evidence of this very limited cyber intrusion into our corporate network in January 2017 …”

My concern with this and the prior statement is that it takes a while for the card brands to recognize fraud.  I have seen it take brands as little as a month to as much as two years for the brands to notify a merchant or service provider that they think there has been a breach.  The reason is that it depends on the extent of the breach (i.e., small versus large merchants, small versus large service provider(s), number of transactions/cards involved), how quickly the cards are used for committing fraud, how quickly those fraudulent transactions are reported back to banks by their customers, how quickly the brands determine a pattern and then that pattern traces back to a likely source or sources.  As a result, I am very suspect as to how long the intruders were in their network and the likelihood that the intrusion was truly as “limited” as Verifone is leading us to believe.

The bottom line in all of this, in my very humble opinion, is that this could just be the tip of the iceberg and this breach could be more extensive than Verifone knows and could have larger ramifications.

Why You Should Care

Given that I suspect that the attackers were in Verifone’s network for a while, I would assume that not just Verifone’s service provider operation was targeted and compromised.

The first clue to this suspicion is that Visa and MasterCard were the ones that notified Verifone that something was going on.  As I stated earlier, the brands take a while to determine a breach which likely means that the attackers were inside Verifone for more than just a short period of time.  In addition, it is rare that PANs collected in a breach are used immediately after they are obtained.  The reason is that there are bigger rewards if they are not used immediately.

The next piece clue in our puzzle is this statement from the Krebs post.

“The source said his employer shared with the card brands evidence that a Russian hacking group known for targeting payment providers and hospitality firms had compromised at least a portion of Verifone’s internal network.”

If this is accurate then it is highly likely that not just card information was gathered.  What also was likely gathered was source code to things like card terminal firmware and software such as Verishield, Verifone’s end-to-end encryption (E2EE) solution.  Any attackers that are focused on targeting payment providers would know that if they were inside of an organization that provides such solutions as Verifone that they should get their software as well as cardholder data (CHD).  If you have the ability to exfiltrate CHD, why not exfiltrate other useful information such as source code, certificates, encryption keys and other sensitive information.

The only good news in this regard is that while a lot of transaction gateways and processors use Verishield, they all have their own certificates and encryption keys.  So the attackers would have only gotten certificates and keys for the merchants processing through Verifone.  Since Verifone is an encryption endpoint, it is possible that the attackers did not get the certificates or encryption keys because they would not necessarily need them to get at the clear text CHD.  However one should ever assume that is the case.

Now What?

The net of all of this is that if you have Verifone terminals and/or Verishield or other Verifone applications, you should probably be doing a lot more monitoring of that hardware and software since there is no reason to believe that it has not been compromised.

It will be interesting as time goes on to see if this is the end of the discussion or if more will come out on the Verifone breach.

07
Mar
17

Verifone Investigating Breach

Just a quick note to everyone since this could affect a lot of merchants and service providers.  Brian Krebs is reporting that Verifone is investigating a possible breach of their systems.  More on it here.

11
Feb
17

The Council Gets A Clue

Late this week the PCI Security Standards Council issued a new information supplement titled ‘Multi-Factor Authentication’ after the brew-ha-ha that occurred last fall at the Community Meeting in Las Vegas.  For once, the Council has issued an excellent reference regarding the issues of multi-factor authentication (MFA).  Although I still have a couple of minor bones to pick about this document, but more on that later.

If you understand the concepts of MFA, you can skip through the document to the end where the Council presents four scenarios on good and bad MFA.  These are well documented and explain the thought process behind why the scenario works or does not work for MFA.  The key takeaway of all of this is the independence of the MFA solution from the logon process.  The Council is getting in front of the curve here and stopping people from creating insecure situations where they believe they are using MFA that minimizes or stops breaches through administrators or users with access to bulk card data.

Now for a few things that I do not necessarily agree with in this document.

The first involves the Council’s continued belief that hardware security modules (HSM) are actually only hardware.  On page four, the following statement is made.

“Hardware cryptographic modules are preferred over software due to their immutability, smaller attack surfaces, and more reliable behavior; as such, they can provide a higher degree of assurance that they can be relied upon to perform their trusted function or functions.”

The Council has made similar statements over the years in the mistaken assumption that HSMs are only hardware.  HSMs are hardware that use software to manage keys.  There are standards that are followed (e.g., FIPS 140) to ensure that the HSM remains secure, but these devices are predominately software driven.  That is not to say that just any device can serve as an HSM, but a lot of us in the security community are concerned that the Council continues to perpetuate a myth that HSMs are only hardware which is patently false.

My other issue comes on page six as part of the discussion regarding the use of SMS for MFA.

“PCI DSS relies on industry standards—such as NIST, ISO, and ANSI—that cover all industries, not just the payments industry. While NIST currently permits the use of SMS, they have advised that out-of-band authentication using SMS or voice has been deprecated and may be removed from future releases of their publication.”

While everything in this statement is accurate, it gives the uninitiated the impression that SMS or voice is no longer a valid MFA solution.  I know this to be true because I have fielded some questions from clients and prospects on this subject, particularly about SMS.  The key is that this is not SSL and early TLS where NIST called them out as insecure and to no longer be used.  This is a “heads up” from NIST to everyone that there is an issue that makes SMS and voice not secure enough for MFA.

But while there is a risk, a lot of us in the security community question the viability of that risk when matched against merchant risk versus a bank or a government agency.  While I would not want any bank or government agency to use SMS or voice for MFA, a small business may not have a choice given their solution.  The reason is that the risk of an attack on SMS or voice is such that only a high-value target such as a bank or government agency would be worth such an effort.  In my very humble opinion, while a total ban is the easy solution, this is an instance where the Council should take a more nuanced approach toward the use of SMS and voice for MFA.  The bottom line to me is that small merchants using any MFA solution, even if flawed, is better than using no MFA solution.

I would recommend the following approach to manage this risk.

  • Level 4 merchants can be allowed to use SMS or voice for MFA.
  • Level 1, 2 and 3 merchants would be allowed to transition away from SMS and voice to a more secure MFA solution within one year of NIST stating that they are no longer acceptable.
  • All service providers would not be allowed to use SMS or voice for MFA once NIST states that both are no longer acceptable. This means service providers should start transitioning now if they use either.

Those are my thoughts on the subject.  I look forward to the comments I am sure to receive.




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