A Few Good Information Security Metrics

Andrew Jaquith says information security metrics don't have to rely on heavy-duty math to be effective, but they also don't have to be dumbed down to red, yellow, green. Here are five smart measurements--and effective ways to present them.

By no means does Jaquith (or CSO for that matter) think these five metrics are the final word on infosecurity. Quite the contrary, they're a starting point, relatively easy to ascertain and hopefully smart enough to get CISOs thinking about finding other metrics like these, out in the vast fields of data, waiting to be reaped.

Metric 1: Baseline Defenses Coverage (Antivirus, Antispyware, Firewall, and so on)

This is a measurement of how well you are protecting your enterprise against the most basic information security threats. Your coverage of devices by these security tools should be in the range of 94 percent to 98 percent. Less than 90 percent coverage may be cause for concern. You can repeat the network scan at regular intervals to see if coverage is slipping or holding steady. If in one quarter you've got 96 percent antivirus coverage, and it's 91 percent two quarters later, you may need more formalized protocols for introducing devices to the network or a better way to introduce defenses to devices. In some cases, a drop may stir you to think about working with IT to centralize and unify the process by which devices and security software are introduced to the network. An added benefit: By looking at security coverage, you're also auditing your network and most likely discovering devices the network doesn't know about. "At any given time, your network management software doesn't know about 30 percent of the IP addresses on your network," says Jaquith, because either they were brought online ad hoc or they're transient.

How to get it: Run network scans and canvass departments to find as many devices and their network IP addresses as you can. Then check those devices' IP addresses against the IP addresses in the log files of your antivirus, antispyware, IDS, firewall and other security products to find out how many IP addresses aren't covered by your basic defenses.

Expressed as: Usually a percentage. (For example, 88 percent coverage of devices by antivirus software, 71 percent coverage of devices by antispyware and so forth.)

Not good for: Shouldn't be used for answering the question "How secure am I?" Maximum coverage, while an important baseline, is too narrow in scope to give any sort of overall idea of your security profile. Also, probably not yet ready to include cell phones, BlackBerrys and other personal devices, because those devices are often transient and not always the property of the company, even if they connect to the company.