AWS GuardDuty: What you need to know

One of the most common recurring questions asked by customers across all business sectors is: How do I monitor security in the cloud?

While extremely important to have good governance, design and security practice in place when moving the cloud, it’s also extremely important to have tools in place for detecting when something has gone wrong.

For AWS customers, this is where GuardDuty comes in.

A managed threat detection service, GuardDuty utilities the size and breadth of AWS to detect malicious activity within your network. It’s a fairly simple concept, with huge benefits. As a business, you have visibility to your assets & services. As a provider, Amazon has visibility of network services along with visibility of ALL customers networks.

Using this, Amazon has been able to analyse, predict and prevent huge amounts of  malicious cyber activity. It’s hard to see the forest from the trees, and GuardDuty is your satellite – provided all thanks to AWS.


In this blog, we’ll cover why AWS GuardDuty is great for cloud security on AWS deployments, its costs and benefits, and key considerations your business needs to evaluate before adopting the service.

Why is security monitoring & alerting important?

Once a malicious actor penetrates your network, time is key.

Microsoft’s incident response team has the “Minutes Matter” motto for a reason.  In 2018, the average dwell time for Asia Pacific was 204 days (FireEye). That’s over half of a year where your data can be stolen, modified or destroyed.

Accenture recently estimated the average breach costs a company 13 million dollars. That’s an increase of 12% since 2017, and a 72% increase on figures from 5 years ago.

As a business, it’s extremely important to have a robust detection and response strategy. Minimising dwell time is critical and enabling your IT teams with the correct tooling to remove these threats can reduce your risk profile.

The result of your hard efforts? Potential savings of huge sums of money.

AWS GuardDuty helps your teams by offloading the majority of the heavy lifting to Amazon. While it’s not a silver bullet, removal of monotonous tasks like comparing logs to threat feeds is an easy way to free up your team’s time.

What does GuardDuty look like?

For those of you who are technically inclined, Amazon provides some really great tutorials for trying out GuardDuty in your environment and we’ll be using this one for demonstration purposes. 

GuardDuty’s main area of focus is the findings panel. Hopefully this area remains empty with no alerts or warnings. In a nightmare scenario, it could look like this:


Thankfully, this panel is just a demo and you can see a couple of useful features that are designed to help your security teams respond effectively.  On the left, you will notice a coloured icon, denoting the severity of each incident – Red Triangle for critical issues, orange squares for warnings and blue circles for information. Under findings, you will find a quick summary on the issue – We’re going to select one and hopefully dig into the result. 

As you can see, a wealth of data is presented when you navigate into the threat itself. You can quickly see details of the event, in this case Command & Control activity, understand exactly what is affected and then navigate directly to the affected instance. Depending on the finding & your configuration,  GuardDuty may have even automatically completed an action to resolve this issue for you.

AWS GuardDuty: What are the costs?

AWS GuardDuty is fairly cheap due to the fact it relies on on existing services within the AWS ecosystem.

First cab off the rank is CloudTrail, the consolidated log management solution for AWS. Amazon themselves advise that CloudTrail will set you back approximately:

  • $8 for 2.15 MILLION events
  • $5 for the log ingestion
  • Around $3 for the S3 storage.
  • Required VPC flow logs will then set you back 50¢ per GB. 

Finally AWS Guardduty service itself costs $4 dollars for a million events.

Working on the basis that we generate about two million events a month, we end up paying only $16 dollars (AUD)

Pretty cheap, if you ask us.

AWS GuardDuty: Key business considerations

GuardDuty is great, but you need to make sure you’re aware of a couple of things before you enable it:

It’s a regional service. If you’re operating in multiple regions you need to enable it for each, and remember that alerts will only show in those regions. Alternately, you can ship your logs to a central account or region and use a single instance. 

It’s not a silver bullet. While some activity will be automatically blocked, you do need to check in on the panel and act on each issue. While the machine learning (ML) capability of AWS GuardDuty is great, sometimes it will get it wrong and human (manual) intervention is needed. AWS GuardDuty doesn’t analyse historical data. Analysis is completed on the fly, so make sure to enable it sooner rather than later. 

Can you extend AWS GuardDuty?

Extending GuardDuty is a pretty broad topic, so I’ll give you the short answer: Yes, you can.

If you’re interested there’s a wealth of information available at the following locations:

Hopefully by now you’re eager to give GuardDuty a go within your own environment! It’s definitely a valuable tool for any IT administrator or security team. As always, feel free to reach out to myself or the Xello team should you have any questions about staying secure within your cloud environment.

Originally Posted on