Protect your backups from ransomware

Don’t get your backup advice from security people. That’s how I felt reading what started out as a really good article about protecting your systems from ransomware.  It was all great until he started talking about how to configure your backup system.  He had no idea what he was talking about. But now I’m going to give you security advice about your backup system, so take it with a grain of salt.

Windows backup servers are risky

Windows-based backup products that store data in a directory are a huge security risk. In fact, many customers of such products have already reported my worst fears: their backups were encrypted with the same ransomware that infected their servers.

This isn’t an anti-Windows rant, or an anti-BackupProductX rant. It’s simply acknowledging the elephant in the room.

  1. If your backup server is accessible via the same network your computers are on, it can be attacked via the same things that attack your computers.
  2. If your backup server runs the same OS as your computers – especially if it’s the OS that most ransomware attacks happen on (Windows) – it can be infected with the same ransomware
  3. If your backups are stored in a directory (as opposed to a tape drive, an S3 object, or a smart appliance not accessible via SMB/NFS), they can be infected if your backup server is infected.
  4. If your backups are stored on a network mount via NFS/SMB, you’re giving the ransomware even more ways to attack you.

What should you do?

I don’t want to be guilty of doing what the security guy did, so I’ll say this: research what you can do to protect your systems from ransomware. But I’ll do my best to give some general advice.

I know the best advice I’ve read is to keep up-to-date on patches and to disable Remote Desktop Management on Windows.  There are also default SMB shares in Windows that should be disabled.

You can also make sure that your backups aren’t just stored in a directory. Unfortunately, that’s the default setup for most inexpensive backup software products. You need to investigate if the software you’re using supports another way to store backups.  If not, it’s time to think about a different product.

The same goes true for those currently storing backups on an NFS/SMB share. Investigate if your backup software has the ability to store backups on that device without using NFS/SMB. If not, make sure you lock down that share as much as you can. Again, if not, it’s time to think about another backup product.

Consider a cloud data protection service

A true cloud-based data protection service might be the best way to do this.  In a true cloud-based system, you never see the backup servers. You don’t know what they are and never login to them. You login to a web-based portal, and the actual servers that make this happen are completely invisible to you.  (Similar to the way the servers that make happen are invisible to you.)

If your backup servers are invisible to you, they’re invisible to your attackers. If there’s no way to directly access your backup – unless you’ve specifically setup such access for a recovery or DR test – then ransomware can’t get to those backups either.

It should go without saying that this recommendation does not apply if your “cloud” data protection vendor is just putting backup software on VMs that you manage in the cloud – what many have dubbed “cloud washing.” If you’re seeing your backup servers as VMs in the cloud, they’re just as much of a risk as they are if they were in your data centers. It’s on the reasons why these cloud washing vendors aren’t really giving you the full benefit of the cloud if all they’re doing is putting VMs up there.

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Written by W. Curtis Preston (@wcpreston). For those of you unfamiliar with my work, I've specialized in backup & recovery since 1993. I've written the O'Reilly books on backup and have worked with a number of native and commercial tools. I am now Chief Technical Evangelist at Druva, the leading provider of cloud-based data protection and data management tools for endpoints, infrastructure, and cloud applications. These posts reflect my own opinion and are not necessarily the opinion of my employer.