Automating alert response with Azure Security Center and Azure Logic Apps

Responding a security event is the core practice in the modern security frameworks. After a potential threat was detected, it is time to act. The shorter the response time is the less damage an attacker can deal to your cloud.

Detection in Azure

Azure Security Center in the Standard pricing tier ($15/VM node per month) comes with automated detection mechanisms. The core detection capability is built around real-time traffic and system logs parsing and applying machine learning algorithms to it:

security-center-detection-capabilities-fig1

A single dashboard can be found under Security Center -> Security Alerts blade and also on the main page of the Security Center:

alertsdetection

Alerts represent single or multiple security events of the same nature and time span. Incidents are created from multiple alerts which are classified as related to each other – for example, an attacker runs a malicious script, extracts local password hashes and cleans the event log. This sequence of action will generate one incident.

Incident forensics

Incidents can be investigated in a forensics tool Investigation Dashboard (in the preview, as of May 2018). This tool draws the relationships between alerts, events that caused the alert, affected resources, users. It also can help when reconstructing lateral movements of attackers within the network.

investigation.PNG

Automated response

Incident forensics represents a post-mortem investigation. An adversary event did happen, and the attackers have already done some damage to the enterprise. We don’t have to wait until malicious actors finish their job – we can start acting right after getting the first signals about the intrusion. Alerts are generated by Azure in real-time, and recently Security Center got a powerful integration with Azure Logic Apps.

Logic Apps in Azure represent workflows of actions with pre-built triggers, conditions, and actions which include a wide range of both native and 3-rd components. For example, your logic app can listen to RSS feed and automatically tweet once new pages are published to the feed. Or, run a custom powershell through Azure Automation.

One of the recent additions to Logic Apps – Security Center triggers. This feature turns Azure security alerts into the powerful tool for fighting attackers once they trip a wire.

You can Security-related Azure Logic Apps under Security Center -> Playbooks (Preview).

Building the logic

After adding a new playbook, a user gets presented with Loic App Designer. The trigger is pre-populated – When a response to Azure Security Center alert is triggered. Once we get an alert, the playbook is executed. Then, we add a condition – there are multiple parameters that the alert arrives with. Let’s take “Alert Severity” and set the condition to High:

trigger

Other alert parameters include Confidence Level, Alert Body, Name, Start or End Time and many more. The range is quite broad which makes it possible to generate very specific responses to almost any imaginable event.

Now, if the condition is TRUE – Alert Severity is High, we want to contain the threat. One of the ways to do so is to isolate a VM under attack. Let’s say, assign it to a different Network Security Group which has no connection to the internal company network or some of its segments. To do it, we would need to get a VM name from the alert and run some Azure Powershell performing the NSG re-assignment.

Creating the Automation Job

Now, we can go to Azure Automation and create an Automation Job for our needs. This can be done through the blades Automation Accounts -> Runbooks -> Add a runbook. As Runbook type, choose “Powershell”.

Then, we insert the following code:

Param(
[string]$VMName
)

$connectionName = "AzureRunAsConnection"

try
{
# Get the connection "AzureRunAsConnection "
  $servicePrincipalConnection=Get-AutomationConnection -Name $connectionName

  Add-AzureRmAccount `
    -ServicePrincipal `
    -TenantId $servicePrincipalConnection.TenantId `
    -ApplicationId $servicePrincipalConnection.ApplicationId `
    -CertificateThumbprint $servicePrincipalConnection.CertificateThumbprint
}

catch {
  if (!$servicePrincipalConnection)
  {
     $ErrorMessage = "Connection $connectionName not found."
     throw $ErrorMessage
} else {
  Write-Error -Message $_.Exception
  throw $_.Exception
  }
}

# Get VM object
$vm = Get-AzureRmVM -Name $VMName -ResourceGroupName AzureBootcamp
# Get NIC
$Nic = Get-AzureRmNetworkInterface -ResourceGroupName AzureBootcamp | Where-Object {$_.VirtualMachine.Id -eq $vm.Id}
# Change Network Security group to IsolatedNetworkNSG
$Nic.NetworkSecurityGroup = Get-AzureRmNetworkSecurityGroup -ResourceGroupName AzureBootcamp -Name "IsolatedNetwork-NSG"
# Apply changes
Set-AzureRmNetworkInterface -NetworkInterface $Nic

This code gets the VMName as a parameter, authenticates to your Azure account with Azure Run-As connection (requires preliminary configuration). Then, it get’s VM’s NIC and assigns it to the security group “IsolatedNetwork-NSG”. Save the automation runbook with name IsolateVM, for instance, and don’t forget to publish the changes after editing Powershell.

Putting it all together

The last step, adding the action to the Azure Logic App we-ve been building. Select “Azure Automation – Create job” and point it to the IsolateVM automation book.

logicapptrue.PNG

Here, we specified “Host Name” as Runbook parameter (notice, it automatically picked up parameter name VMName that we created int he runbook).

Save the logic – and this is it. Once an alert is generated a VM is expelled to the isolated security group with limited access.

Testing and tuning the playbook

To test this integration before an actual event happens, go to any of previous events in Security Center – Security Alerts (you can generate them, for example, by trying to downloadMimikatz from Github), click on the event, then click on “View playbooks” button. In the new window find your Logic app workflow and press “Run” under “Run playbook”:

runpalybook

This will send exactly same trigger as this alert would have done. From the playbook run window or Run history, you will be presented with a static view similar to Logic App Designer with the only difference that it contains the logic path that was taken in this run:

logicexecution

Actual inputs that were submitted with the trigger can be viewed by expanding “When a response to an Azure Security Center alert is triggered” section.

alertdescription

The Azure Security Center alerts integration with Logic Apps provides limitless capabilities not only for informing about detections (via email, Slack, Skype) but also for an automated response to potential attacks with auto-tuning cloud infrastructure and isolating the threat, a show in the example.

Have fun building your own playbooks and fighting the threats before they become incidents.

Stay secure!

Identifying threats: Software inventory of Azure VMs

Azure VMs recently got a bunch of new features – Inventory, Change tracking and Update management (became GA on 8th of March, 2018). These features fill the gap in identifying the software that is deployed to IaaS clouds – the information necessary for securing these resources. The features are based on the Azure Automation capabilities and require an Automation account to run the workloads.

Inventory feature provides visibility into software installed on a VM (can be accessed from the individual VM blade), services, Linux daemons and also the timeline of events as part of the change the tracking view.

in2

VM view:

Inv1

In this example, we can see Adobe Flash Player and Steam client installed on the machine – both are increasing the attack surface for this infrastructure.

If you want to get more detail overview – proceed to Log Search tab. For example, this query will yield all non-Microsoft applications inventoried in the past day:

ConfigurationData
| where ConfigDataType == “Software”
| where SoftwareType == “Application”
| where Publisher != “Microsoft Corporation”
| order by TimeGenerated desc

logsearch1

The Change tracking view provides the visibility into the software changes and allows to track them efficiently. Also, you can add particular files or registry entries to watch. Watching entire folders is not yet supported for Windows VMs.

ch1.GIF

To get an overview of multiple machines either:

  • Click “Manage multiple machines” on Inventory or Change tracking view blade
    ch2
    This view also can be used to add non-Azure VMs through the Hybrid worker functionality.
  • Or go to the automation account that was associated with Inventory and Change tracking when first enabled. It also provides a convenient view of associated machines.

Update management can find machines with missing OS updates and fix it by scheduling a deployment.

upd1.PNG

Update management is integrated into the Security Center so that critical updates are never left out for all machines in the cloud. But it is important to remember to turn on these features first.

At the moment, only Update management allows taking an action based on the gathered data. Inventory doesn’t have a built-in functionality to remove unwanted applications or perform an on-demand scan. Also, it is lacking reporting capabilities and global overviews of applications in the cloud. Change tracking data can be used only for setting up custom alerts (requires Log Analytics knowledge).

At the same time, based on the direct connection of these features to the Azure Automation, I expect there will be more functions added to make it possible to fix found issues and secure a resource based on the Inventory data. It is clear that Microsoft is taking an important action in securing IaaS – and providing the data is only the first step.

P.S. For more advanced Inventory and Software Asset Management solutions, one may look into 3-rd party providers such as Snow Software (where I work at the moment).