The calls start rolling in at 2am on Sunday morning. Alerts start firing off. Your livelihood is in grave danger. It doesn't come with the fanfare of a blockbuster Hollywood thriller, but if a server hosting your critical business infrastructure is attacked, becomes compromised or fails, it might feel like the end of the world. In our Risk Management series, and we've covered the basics of securing your servers, so the next consideration we need to make is for when our security is circumvented.
It seems silly to prepare for a failure in a security plan we spend time and effort creating, but if we stick our heads in the sand and tell ourselves that we're secure, we won't be prepared in the unlikely event of something happening. Every attempt to mitigate risks and stop threats in their tracks will be circumvented by the one failure, threat or disaster you didn't cover in your risk management plan. When that happens, accurate event logging will help you record what happened, respond to the event (if it's still in progress) and have the information available to properly safeguard against or prevent similar threats in the future.
Like any other facet of security, "event logging" can seem overwhelming and unforgiving if you're looking at hundreds of types of events to log, each with dozens of variations and options. Like we did when we looked at securing servers, let's focus our attention on a few key areas and build out what we need:
Which events should you log?
Look at your risk assessment and determine which systems are of the highest value or could cause the most trouble if interrupted. Those systems are likely to be what you prioritized when securing your servers, and they should also take precedence when it comes to event logging. You probably don't have unlimited compute and storage resources, so you have to determine which types of events are most valuable for you and how long you should keep records of them — it's critical to have your event logs on-hand when you need them, so logs should be retained online for a period of time and then backed up offline to be available for another period of time.
Your goal is to understand what's happening on your servers and why it's happening so you know how to respond. The most common audit-able events include successful and unsuccessful account log-on events, account management events, object access, policy change, privilege functions, process tracking and system events. The most conservative approach actually involves logging more information/events and keeping those logs for longer than you think you need. From there, you can evaluate your logs periodically to determine if the level of auditing/logging needs to be adjusted.
Where do you store the event logs?
Your event logs won't do you any good if they are stored in a space that is insufficient for the amount of data you need to collect. I recommend centralizing your logs in a secure environment that is both readily available and scalable. In addition to the logs being accessible when the server(s) they are logging are inaccessible, aggregating and organize your logs in a central location can be a powerful tool to build reports and analyze trends. With that information, you'll be able to more clearly see deviations from normal activity to catch attacks (or attempted attacks) in progress.
How do you protect your event logs?
Attacks can come from both inside and out. To avoid intentional malicious activity by insiders, separation of duties should be enforced when planning logging. Learn from The X Files and "Trust no one." Someone who has been granted the 'keys to your castle' shouldn't also be able to disable the castle's security system or mess with the castle's logs. Your network engineer shouldn't have exclusive access to your router logs, and your sysadmin shouldn't be the only one looking at your web server logs.
Keep consistent time.
Make sure all of your servers are using the same accurate time source. That way, all logs generated from those servers will share consistent time-stamps. Trying to diagnose an attack or incident is exceptionally more difficult if your web server's clock isn't synced with your database server's clock or if they're set to different time zones. You're putting a lot of time and effort into logging events, so you're shooting yourself in the foot if events across all of your servers don't line up cleanly.
Read your logs!
Logs won't do you any good if you're not looking at them. Know the red flags to look for in each of your logs, and set aside time to look for those flags regularly. Several SoftLayer customers — like Tech Partner Papertrail — have come up with innovative and effective log management platforms that streamline the process of aggregating, searching and analyzing log files.
It's important to reiterate that logging — like any other security endeavor — is not a 'one size fits all' model, but that shouldn't discourage you from getting started. If you aren't logging or you aren't actively monitoring your logs, any step you take is a step forward, and each step is worth the effort.
Thanks for reading, and stay secure, my friends!