A considerable portion of the PCI DSS concerns access control mechanisms, which must be sufficiently robust and comprehensive to deliver the protection required for cardholder data.
Requirement 7 of PSS DSS clearly states that you must restrict data access. You have to ensure that critical data can be accessed only by authorized personnel and that you have the appropriate systems and processes in place to limit access based on business needs and job responsibilities. The requirement also calls for you to immediately remove access when access is no longer needed.
Try to keep the number of people who need access to data to the absolute minimum, with access needs identified and documented according to defined roles and responsibilities.
The standard requires you to think very carefully about who in your organization has access to system components and the effect of that access on the security of your cardholder data environment. This task becomes much more complex if you have multiple office locations or data centers, or if you use cloud-based service providers to host some of your data.
You’re required to manage your access control policy at quite a granular level, carefully defining the various user roles in your organization (user, administrator, and so on) and specifying which parts of your system and data they can access.
In practice, you need to implement sufficient controls to create a practical, effective access control policy, so spend sufficient planning time to devise the best mechanism to satisfy your needs.
The standard is prescriptive in that it forces you to grant “least privilege” access rights to all user accounts with requests for access documented and approved. The logic is that you grant each person only enough access to the various bits of the system or data he or she needs to perform his or her job functions. An administrator, for example, could define an access policy for another user to view the cardholder data, but she herself wouldn’t be able to read the data directly.
Depending on your environment, you may need to address multiple system types and varying levels of access for network, host, and application-level use and administration. This task can prove to be complex when, for example, you need to give multiple types of users different access rights to your databases.
It’s best to disable access to data by default and then enable any access that’s required. This method makes it easier to prevent access-granting mistakes that could lead (in the worst-case scenario) to a data breach.
When a user has a change of role internally, document the change, and modify that user’s privileges as appropriate. Similarly, when a user leaves your company, you need to document the change and then disable or delete his or her user account in alignment with your organization’s policy and procedure.
An established, consistent process can help ensure strong privilege management. In addition, Thales recommends that you periodically run queries on user accounts to verify account activity. You might run a scheduled script on a quarterly basis, for example.
Note: This material is drawn from PCI Compliance & Data Protection for Dummies, Thales Limited Edition, by Ian Hermon and Peter Spier.