So Many Logs, So Little Time

Written by Walter Conway
September 15th, 2010

A 403 Labs QSA, PCI Columnist Walt Conway has worked in payments and technology for more than 30 years, 10 of them with Visa.

PCI’s logging requirements present a particular challenge for retailers, especially those with multiple store locations. How does a retailer with a large number—even thousands—of remote devices efficiently log, harvest those logs and review them daily? Reaching for a vendor suite right away may sound easy, but that is only the beginning of an answer.

Once that suite is in place, retail CIOs should plan for a risk- and security-based assessment of their log management needs and allocate the resources to make the system work. Otherwise, retailers may centralize their logging but find themselves overwhelmed by the white noise of too much data. Or, IT could distribute log reviews down to the store level only to learn that the individual locations cannot achieve separation of duties, back-ups or daily log reviews conducted by someone who knows what he or she is doing.

No simple answers exist. Both centralized and decentralized approaches can be made to work in theory, but the more important factor is taking the time to select and tune your logging system, for whichever approach you follow.

PCI Requirement 10 addresses monitoring of all access to all in-scope system components and cardholder data. It describes what events to log (10.2: for example, all user access to cardholder data, administrator actions, invalid access attempts) and what entries need to be recorded (10.3: for example, user ID, date, time, success or failure).

All QSAs are pained when they hear a client say: “We just bought XYZ log management package, so we’re all done with logging for PCI.” The reason for this pain is that buying the application is only the first of many steps necessary to achieve an effective logging function. Retailers—especially those with multiple store locations—need to budget time and resources to tune their logging approach so it is effective.

For example, a log management application may be able to monitor failed login attempts in Windows, but this step is just the beginning. The system still needs to be customized for the specific applications, devices (e.g., firewalls, routers, even wireless), antivirus, IDS/IPS and remote access (e.g., VPN) in a retailer’s cardholder data environment. That means retailers need to customize their logging so it can monitor the chain’s different databases and POS and Web applications.

The next step is to tune the logging system so it provides the alerts you need to see without overwhelming you with an avalanche of false positives or unnecessary alerts. Tuning can be a major effort, and the system must be updated regularly. One key theme is relevance. The other is having the log reviews done by people who know what they are doing.

PCI Requirement 10.6 deals with daily log review. The rationale is that the sooner suspicious activity—such as failed administrator log-in attempts or a successful login to a sensitive system by an authorized administrator but without a reason—is uncovered, the sooner you can act and limit any damage. The result is that tuning is particularly important for retailers with hundreds or thousands of store locations, if they are to comply with this requirement.


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