The last time we got together we talked about data integrity. Make sure you brush up on that one really fast. (if you haven't look at it)
It's a short read but it's critical because it lays the foundation for everything else you're going to learn in this training.
Today I want to talk to you about Data Availability. This is the third reason business leaders and organizations have cyber security and information security programs and it'll round out our mini-series on cyber security goals.
Imagine you're hanging out with a few of your buddies in the local bar and a stunning girl glides in and sits right next to you. She orders a glass of wine and then turns her head in your direction and mesmerizes you with her looks.
Her elegance and beauty almost makes you barf up your beer.
So understandably, you're nervous. In fact your legs are visibly shaking and your throat is getting a little dry but you somehow cough up the courage to ask her if she's "taken".
"Excuse me, uh... are you.."
She gazes back at you with an intoxicating smile as she waits for you to complete your thought.
You gasp for breath and stumble over the words like a clumsy ogre...
"Excuse me, um are you available?"
Hearing the cowardly horseness in your voice make you feel sick.
Just then, a hulking man about three times your size, struts up behind her, runs his arms around her neck and gives you a stare down that makes your heart skip a beat.
Whoa! what happened?
She's not available. And you are understandable frustrated but let's face it: you should have guessed that a girl that hot couldn't be alone right?
So what's my point? Well if a web server or network system is available that means people can access it with needed. And when people can access network resources they are happy.
In our hypothetical bar scene, your potential date wasn't available because she was taken and you were frustrated. This is exactly how users can feel when the internet resources they rely upon go down or is taking too long to respond. If the server is "taken" by processing too many network requests it can become unresponsive.
There are two ways information security professionals can tackle this problem:
Let's dig into these really quick:
Fault Tolerance means your system can tolerate a fault without service interruption.
So a power supply in a server can die without taking down the entire server or an entire datacenter can get blown up by a bomb and not take the organization down.
How is this possible?
Glad you asked! It's all about data redundancy.
I know I typed it twice, I was trying to be redundant. I know I typed it twice, I was trying to be redundant.
Okay, that's not funny anymore. hahah.
The goal of data redundancy is to remove a single point of failure (SPOF).
In the case of the data center explosion, you might have a separate data center in a separate city that's ready and available 24 hours, 7 days a week. This is known as a hot site and is obviously pretty expensive. The hot site mirrors your main site so if the main site fails, the hot site immediately becomes available.
Now most companies can't afford a hot site so they might have another location where hardware can be moved to and setup when needed. This is a cold site and is usually the most cost effective solution.
Or how about this:
Let's say you have three servers that are delivering the same web content to a domain name you own; let's just call it example.com.
If one of those servers gets infected with malware and drops offline that's okay because your website example.com continues to work as it runs off the other two servers.
Or if a script kiddie fires up a hacking tool such as Low Orbit Ion Canon and targets your web server in an attempt to deny service to legitimate users, your web server can distribute the load across all three physical servers to prevent the site from crashing. This is known as load balancing and it is an effective technique for removing a single point of failure on network resources.
Having multiple servers supporting the same purpose is also known as having a failover cluster because any server in the cluster can fail while allowing the others to continue operating .
Failover clusters are pretty awesome because they reduce unplanned downtime and improve the overall user experience.
The other way you can maximize availability is through disk redundancy. Instead of installing the operating system on a single disk you could duplicate it across two physical disks. This is great because it allows your system to continue humming along even if one disk fails. InfoSec Pros call this RAID-1 and there are actually several RAID levels but we'll get into those details later.
There are several other techniques we can use to maximize data availability that we haven't talked about. The easiest and perhaps most overlooked technique is to simply have a reliably backup strategy. Many companies don't keep backups and the few that do, don't have a consistent policy of testing those backups to make sure they actually work!
If an unscrupulous employee in the accounting department opens an Excel workbook from an unknown sender which contains a malicious macro that downloads malware and encrypts the accountants hard drive and demands payment for decryption, then well... if you don't have any backups you'll need to pay up or suffer that loss.
This is one of the reasons backups are so critical.
Power Backups are also a good thing to have. Uninterruptible Power Supplies (UPS)s are good because they can keep your critical systems online even when the power fails. Most companies will install massive USP rack units in a main distribution facility (MDF) or data closet. And they'll plug each UPS into a different power utility line so if one line fails the other one can continue charging the other UPS.
So that's all you need to know for the cyber security goals. If you want a quick review you can skim back through the other training pages or you can just down download a quick sheet that summarizes all three posts in a single sheet.
So that's it for this mini-series next time we'll continue our Security+ prep with some more topics so make sure you bookmark this site and check back often.
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