Tag Archive: MDATP

Hunting Windows Defender Exploit Guard with ATP

Alright, since I happen to be in a blog mode I keep the posts coming.

This post continue to explore the hunting capatibilities in Defender ATP by query for Exploit Guard detections.

So what’s this Exploit Guard?

Windows Defender Exploit Guard is a new set of intrusion prevention capabilities which are built-in with Windows 10, 1709 and newer versions.

Exploit Guard consists of 4 components which are designed to lock down the device against a wide variety of attack vectors and block behaviors commonly used in malware attacks, while enabling enterprises to balance their security risk and productivity requirements

ComponentDetails
Attack Surface Reduction (ASR)A set of controls that enterprises can enable to prevent malware from getting on the machine by blocking Office-, script-, and email-based threats
Network Protection Protects the endpoint against web-based threats by blocking any outbound process on the device to untrusted hosts/IP through Windows Defender SmartScreen
Controlled Folder AccessProtects sensitive data from ransomware by blocking untrusted processes from accessing your protected folders
Exploit ProtectionA set of exploit mitigations (replacing EMET) that can be easily configured to protect your system and applications

Example of ASR rules

• Block Office apps from creating executable content
• Block Office apps from launching child process
• Block Office apps from injecting into process
• Block Win32 imports from macro code in Office
• Block obfuscated macro code

Exploit Guard is configured through MDM (Intune) or SCCM or GPO’s or PowerShell.

If you have Microsoft 365 E5 license or Threat Protection license package, you don’t have to use Windows Event Forward to get the events in a central log solution. They will automatically be forwarded to your Microsoft 365 security portal https://security.microsoft.com where you have a nice looking dashboard where you can see alerts and configurations of ASR and other things.

This following dashboard is a part from the Monitor and Report section in the portal

Back to Defender ATP and the hunting which this post was supposed to be all about.

We have published some posts now about hunting custom alerts.

In the query console in Defender ATP we started to go backwards to find the ASR events. It’s simple. configure your client, run a few attacks which will trigger the alerts.

We looked in the MiscEvents for all events (filtered on computername and time). Which gaves us ideas of ActionTypes to use in the query.

Examples from the output:

AsrOfficeMacroWin32ApiCallsAudited
AsrPsexecWmiChildProcessBlocked
ControlledFolderAccessViolationBlocked
ExploitGuardAcgAudited
ExploitGuardChildProcessAudited
ExploitGuardNetworkProtectionBlocked
ExploitGuardNonMicrosoftSignedAudited
ExploitGuardWin32SystemCallBlocked
SmartScreenAppWarning
SmartScreenUrlWarning
SmartScreenUserOverride

Interesting note “SmartScreenUserOverride” is a separate event which you can query

When we had the raw Actiontypes we created the query to cover as much as we could.

//Happy Hunting
MiscEvents 
| where ActionType contains "asr" or
        ActionType contains "Exploit" or
        ActionType contains "SmartScreen" or
        ActionType contains "ControlledFolderAccess"
| extend JsonOut = parse_json(AdditionalFields)
| sort by EventTime desc 
| project EventTime, ComputerName, InitiatingProcessAccountName, ActionType,  
         FileName, FolderPath, RemoteUrl, ProcessCommandLine, InitiatingProcessCommandLine,
         JsonOut.IsAudit,JsonOut.Uri,JsonOut.RuleId,JsonOut.ActivityId
         

We are also parsing AdditionalFields to be able to add extra value to events which contained such data.

From this point we can do additional filters. For example, if you want to enable ASR enterprise wide, set them in auditmode and report on the alerts without affect user productivity, remediate and the do a enterprise wide block enrollment

Happy Hunting!

Automate response with Defender ATP and Microsoft Flow

So now when we have cool products (more or less builtin) we need to start working with them and not be required to look in the portals 24/7.

This post will demonstrate an example on how to use approval in email to isolate machines with new alerts.

Microsoft Flow is very easy to use to create business flows for all kind of products. You can manage anything which has an API.

Microsoft has released connectors for many solutions and by drag n drop you can create flows to make your life a lot easier.

This flow used in this blog post is just to be able to show something useful.

  • Start by browsing to https://flow.microsoft.com and create a new flow
  • Search for WDATP and select the Trigger “Triggers when a Windows Defender ATP alert accurs (preview)”

We will then add an action to “Get single alert preview”, this will give us more information to use later.

In below picture we can see some of the dynamic content we can add to next step in the flow

We can also add a condition. In this example we use condition for alert severity (high or medium).

We also want to add an approver step.

For some reason the Approval type is in Swedish for me. You have 2 default options and one custom option
Options are “Everyone must approve” or “First one to approve”.

Based on the response from the approval step we continue the flow with a condition to go ahead if the responder choose to approve the action.


We add the action “Isolate machine (preview)” and configure that along with a send email action.

Running the Flow

If you need to change your flow you can re-run it using the same data as used previously

After the approval we get the status message send to all approvers

We can see that our test machine was successfully isolated

In the flow test overview

From the ATP console we now have the option to release the machine from isolation, collect investigation package etc

Dynamic content

Actions

Pro tips:

  • Use get alert to be able to add more dynamic content to use in subsequent steps
  • Use get machine to be able to get more information like IP, Computername etc
  • Start building your automated playbooks. This will save you time