ISO 27001 vs PCI-DSS: Security Management vs Security Controls Standards

I've seen many discussions from people looking to align to ISO 27001 that lead me to believe that there is still quite a misconception about what the standard is and how it works.

For many organisations, the past few years have featured the letters PCI-DSS quite prominently. Brought in to regulate the manner in which credit and debit card data are managed following a number of significant and high-profile losses, the Payment Card Industry Data Security Standard defines in exacting detail the controls that need to be applied to protect the data and how they should be tested and audited. The standard defines specifically the data it needs to protect and applies it to anyone storing, processing or transmitting this data. Consequently, almost all retail companies and any other businesses that accept card payments need to implement it and ensure that any service providers they use also meet the requirements of the standard.

The reason that PCI-DSS is able to be so prescriptive in its security controls and auditing requirements is that there are a significant number of constants in play, regardless of the size of business. The data requiring protection is always the same type (card numbers, cardholder name, expiry date, etc) and the controls for each data type are therefore constant. The threats to the data are the same and the level of impact is only dependent on how many payment cards are being handled. The risk assessment side has already been done in advance and the controls defined to appropriately reduce them. This is all defined regardless of the type of business, size of business or other threats that may be present in wider enterprise of the businesses in question.

Why is ISO 27001 different?

Unlike the security controls-based PCI-DSS, ISO 27001 does not apply to any particular industry sector, type of data being protected or specific risks or threats. It is a security management-based standard that expects the organisations implementing it to work out these factors for themselves and continually assure their effectiveness. You can therefore apply ISO 27001 to a multinational IT services provider, seeking to protect assets including corporate data; client data; research and development data; IT systems; the buildings and datacenters where the data is housed; the staff, contractors & client personnel; and their business reputation. These are all things which have value to the company and which have vulnerabilities of their own, which are subject to threats and which are therefore facing a level of risk from certain internal and external factors.

Conversely, you can also apply ISO 27001 to "Bob's Corner Shop". Bob may run a single shop in which he has assets including himself and a couple of staff, the shop itself, stock/inventory and perhaps a PC on a desk which he uses to keep records of stock levels and maybe customer accounts. These things are still assets to Bob and still have vulnerabilities and threats posed to them. The impact of Bob's PC crashing and having to be rebooted though is somewhat less than the impact to the IT services provider example above losing power to its core IT infrastructure. The risk therefore is different. Bob also needs to consider things like physical and environmental security, but his controls are more likely to be a good lock on the door, a burglar alarm and a modest air conditioning unit - somewhat different to the multi-factor defense in depth biometric controls, 24/7 guard-force monitoring CCTV and complex HVAC systems deployed by the IT company.

The important thing is that the controls you choose to avoid, mitigate or transfer the risk need to be appropriate. A security control is only appropriate if the cost of implementing and running it is less than the cost of the risk it mitigates, should a security event/incident occur. If Bob decides to implement a two-factor biometric access control system for the store and an enterprise-level anti-virus system for his PC, then he'll be spending far more on those controls than the cost of replacing the assets he's trying to protect. If Bob wants to be able to accept credit card payments, then he will most likely chose to pay a fee to a payment processing service, rather than implementing his own PCI-DSS accredited IT network.

It is because of these differences between the various adopters of ISO 27001, their risk levels and appetites, that the controls cannot be prescribed and specific within the standard itself. If ISO 27001 were to mandate controls at the enterprise level, then Bob would never be able to align his business to that standard. Conversely, if the standard were to only implement a door lock and a burglar alarm as the sole physical security controls, this would not appropriately address the risks facing a data centre.

Managing to both ISO 27001 and PCI-DSS is about constantly assessing risk and reviewing measurements of effectiveness which could be taken from audits, events or ad-hoc observations. The main difference between the two is that for PCI-DSS, this is being done by the PCI Security Standards Council who will release updates to the PCI standards in the event that the current controls need updating to address a new set of risks or threats - businesses managing to PCI-DSS will still audit, but just to ensure that they are meeting the defined controls. The risks that might affect the PCI standard will however only be based on new threats or risks only to payment card data rather than an entire enterprise, with any factors that may affect the standard perhaps not occurring very often. The mandate for compliance globally for all organisations handling this data also makes it more difficult to change the PCI-DSS standard too often.

Where PCI-DSS will remain static until the next version is released, the controls implemented for ISO 27001 could change in response to a specific incident, a change of risk profile based on new threats or the change of management risk appetite. Therefire, with support thorough management and down into the organisation, the policies in place for ISO 27001 can bend and flex gradually to deal with changing risks.

ISO 27001 and PCI-DSS sit very well together within an enterprise. The security management to ISO 27001 will assess all risks to the enterprise across all assets and will define appropriate controls to appropriately mitigate those risks to a level within the risk apetite of the company. Provided the ISO 27001 controls defined meet the requirements of PCI-DSS for those systems in scope for handing payment card data, then it fits nicely into the security management system. It may be that the risks assessed for the enterprise mandate stronger controls than PCI-DSS in some areas, in which case an enterprise-wide control will automatically meet the requirements of the PCI-DSS standard. If the risk assessment determines that a lower level of control is required, then provided the systems in scope meet the requirements of the controls in PCI-DSS, all other systems can be managed in line with the lesser enterprise controls.

Photo: Photostock

Do I trust you with my most precious asset?

Getting security into the mindset of others and helping them to appreciate the benefits that security provides from the outset can be difficult. As you may already have seen, I do like to use analogies to put security into the context of a subject that others are familiar with. For service providers and outsourcers, a useful example is to look at potential customers as parents who are choosing a school for their child. Having been through this process recently myself, I've been able to draw some useful comparisons to with similar examples in business.

For parents choosing a school for their child, particularly the first school for their first child, this can be quite a daunting experience. Your child is your most valuable asset and for the most part you have been their primary influence, been responsible for defining every facet of their existence and for making every choice in their life. You have had complete visibility of everything they do and how each experience has made them the person they are today. The time has come however to entrust part of that responsibility to someone else, someone you don't know and of whom you have little visibility of how well they will continue the work that you have started. You can read reports from Ofsted (the schools inspector) who will define how well the school is performing against others in the area, you can look back into the history of the school and its performance and the exam results it has produced. You may speak to parents of children already in the school to see what they think of it or perhaps listen to rumours and stories in the local conscious about the school.

There is certainly a lot of information about to help parents make a judgement on a school for their child but the key element for many is the point when they get to visit the school and meet the head teacher. Until this point, the information gleaned has either been based on empirical results or second hand information from others. Seeing the environment for yourself and meeting the head teacher and most likely other members of staff will be the first opportunity to form your own opinions and ask your own questions. For many, this may be the differentiator and may be the biggest factor in how you make your decision. The figures will show how good the results are, but parents still want to know how their child will be engaged with and treated during their time at the school and will also want to know that they will be protected from harm and any risks that their children may face during their time there. Parents also have varying preferences for reporting and information. Some will be happy to entrust their child to the school with complete faith and rely only on report cards and parent-teacher meetings to get feedback. Other parents will want to know the minutiae of how each lesson is taught. Much of the assurance parents are going to get from this meeting is their confidence in the school and the staff to keep their child safe and secure in an environment outside of their control. Only if information provided in these meetings is to the satisfaction of the parents will they make the decision to entrust their child to the school.

This is very similar to businesses outsourcing elements of their IT or moving to a managed service. At a time when many companies are feeling the pinch from the economic downturn they may be turning to outsourcing to save costs and for many this may either be their first time or be the most significant move to entrust their data to another organisation. Without anywhere near as much information and visibility of prospective providers as they have of their own company, they will seek to gain as much information and assurance as possible. Analysis of the providers' performance and capabilities will give potential customers a good baseline on a shortlist. The really valuable information to differentiate a service provider from its competitors will come from the detailed and specific information that is exchanged throughout the bid process. Assurances that the supplier can deliver the required solution to the required standards will be a key measure, along with the cost effectiveness of the work. Customers also want assurances which may not be as easily set in stone as the technical design and cost. Making sure that their data is available when they need it will be defined within SLAs and recovery objectives but how can they be sure that the measures that make their information so highly available to them and their customers won't make it available to any unauthorised parties?

Security assurance can often be given in terms of certifications or accreditations held and the results of audits conducted. A visit to a service provider's facility will give customers peace of mind that the physical security controls are sufficient to protect their data, as well as the required environmental and power resilience controls. Customers will bring their own security people to talk to the service provider, and whilst the IT people are discussing how many megabits-per-second they need to transmit their data, gigabytes of RAM to process it and terabytes of disk space to store it, the security people will want to make sure that the data is being transmitted, processed and stored in an appropriate manner with controls that suitably mitigate the risk. The security people need to give assurances to their business that the data they entrust to the service provider is safe and properly protected from threats. This can be a make-or-break factor in any deal and will often require more than just assurances of compliance with any mandated regulatory standards. The security person that the service provider includes in that meeting needs to be able to give the customer the assurances they need that their data will be in safe hands and will be treated with the same care and consideration as if they had maintained it in-house.

Security built into a solution from the start is therefore more than just a technical solution consideration but requires a full risk-focussed assurance role to give potential customers the confidence they need that not only their service but their data will be safe in the service provider's hands.

Photo: Arvind Balaraman