Custom IOCs in Defender ATP

Working with custom IOC can be done via the UI or script (Powershell or Python).

This post will describe the UI way for creating a custom IOC

Go to settings and in the Rules section click on Allowed/Blocked List

You can create an IOC based on File hash, IP address and URLs/Domains

When creating a new IOC you have the options to Import (more on that later) and a wizard.

We click on the Add indicator text and start by filling in the template.

To get the filehash you can just use powershell “get-filehash” or if you have that information from another system or a list from somewhere.

You can set the Custom date for IOC expiration if you want.

You can at this point look at the impact for this IOC by clicking on the Show statistics which will get the data for that specific ile hash from the last 30 days

From this view you could take action and stop the file if needed depending on the situation.

Click next and add details for response action, alert details etc

Scope the machines to different machine groups

Click save in the summary.

Import IOC

The CSV template is comma separated


New alert

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

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:


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
| 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,

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!

Defender ATP and PowerBI

Maybe, you don’t want management in the ATP portal, even though it’s configurable via roles, and maybe they don’t want to be there.

One thing I know is that most managers loves numbers, so why not provide them with a PowerBI report.

You can perfectly use cloud based option and there is an app for Windows Defender ATP already there for you to use.

Configure your connector and you’re all good to go

The dasboard looks like the following picture

With the many different tiles you, or your manager, can dig deeper in to events like in this following example with alert status

It’s also possible to filter data based on who a case was assigned to, who resolved the case etc.

If you have a PowerBI Pro account, you could subscribe to get scheduled reports.

You can also to quick filter

This is an easy win for your manager

Running Windows Sandbox in a VM

The feature Sandbox available in Windows 10 preview version is very intersting for us who uses a web browsing VM.

The Sandbox feature or disposable VM is a Windows 10 container running on your Windows laptop and gives you the opportunity to launch a temporarily VM if you want to test something or just use it to browse internet to avoid infecting your machine (see the “note” later in this post because bad things can still happen) .

When you close the application all files are removed and possible malware will die.


You might want to test the feature on a VM, which will basically be running VM on a VM (nested).

If you open features you will see that the feature is grayed out and you won’t be able to enable it that way however you can enable the service with DISM.

But when you launch Sandbox it will complain.

To solve this you have to make a change on the VM CPU where you want to run Sandbox.

The only thing you have to do is enabling “Expose Virtualization Extensions”

Set-VMProcessor -VMName Windows10Prev -ExposeVirtualizationExtensions $true
powershell set exposevirtualizationextensions to true

On the VM side

Enable the feature using GUI or PowerShell and restart.

dism /online /enable-feature Containers-DisposableClientVM

Launch Sandbox app

windows 10 disposable vm

This feature is perfect instead of using and manage a VM for this kind of work.

Launch Sandbox as any other applications

Note: You will still have access to resources on the network. Therefore malware can still execute and do bad things. But they will not survive a reboot of the Sandbox but they might have already replicate themselves to another system.
You can reach other systems via RDP.
If you have your host enrolled to WD ATP, and you isolate the host, the Sandbox will still be available

The AV Engine doesn’t seem to be running either

But regardless of the “Note” it’s still a very interresting feature and it will help a lot

When you exit the application you will be prompted that all data will be lost

sandbox exit

Vulnerability in Microsoft DHCP server


This is a high priority patch for your Windows DHCP server. This RCE is executed by sending a speciallly crafted packet to the DHCP server.
We haven’t seen any public available information like Proof of concept or exploit code but that’s just a matter of time.

CVSS Score


For further information please visit:

Security update guidance:

SEC-LABS recognized at August 2018 Security Researcher’s list at MSRC

The Microsoft Security Response Center (MSRC) is pleased to recognize the security researchers who have helped make Microsoft online services safer by finding and reporting security vulnerabilities. Each name listed represents an individual or company who has privately disclosed one or more security vulnerabilities in our online services and worked with us to remediate the issue.


Both Stefan Schörling and Mattias Borg from SEC-LABS R&D is recognized at the Microsoft Security Response Center security researchers list for August 2018.

This was due to a vulnerability discovered with Johan Dahlbom and was reported to Microsoft.

We would like to give our appreciation to the MSRC team and it was a pleasure working with you to resolve this issue!

The list can be found here:

SSH native in Windows 10 1803

If you manage a mixed platform your might be switching between, RDP sessions, Remote PowerShell and other remote Tools.

Except for old legacy applications which may not be possible to manage without a GUI, it’s easier, possible to automate and will save you a lot of time using a command line interface.

To extend this support, there is now a native SSH client in Windows.

You may want to check your firewall rules to Control who and where admins can connect and what you need to block

KrackAttack – Vulnerability in WPA2 – Disclosed

A security researcher Mathy Van Hoef will disclose a vulnerability in WPA2 within a few hours.

The vulnerability leaves Wi-Fi traffic open to eavesdropping and it will be possible to inject malicious content and much more.



Important URLs


Van Hoef on Twitter


From Krackattacks.com

Our main attack is against the 4-way handshake of the WPA2 protocol. This handshake is executed when a client wants to join a protected Wi-Fi network, and is used to confirm that both the client and access point possess the correct credentials (e.g. the pre-shared password of the network). At the same time, the 4-way handshake also negotiates a fresh encryption key that will be used to encrypt all subsequent traffic. Currently, all modern protected Wi-Fi networks use the 4-way handshake. This implies all these networks are affected by (some variant of) our attack. For instance, the attack works against personal and enterprise Wi-Fi networks, against the older WPA and the latest WPA2 standard, and even against networks that only use AES. All our attacks against WPA2 use a novel technique called a key reinstallation attack (KRACK):

  • Basically all Wireless networks are vulnerable and the vendors are working to get the patches out.
  • Microsoft was mitigating this on the client side in the October patch release cycle
  • If you won’t get an update to your router your really only option is to get a new one (if it’s out of support)
  • Recommendations are to apply patches as soon as they’re available.



This post will be updated

Security by obscurity is not so obscure

This scenario was discoverd in the real world.

A VPN solution which had a device verification functionality which is all fine but the problem was that the verification is executed only on the client side.

And you don’t only want to protect from external attackers but also users connecting their home PC to the internal network.

We only want managed devices on the inside and one unmanaged home device with i.e. no AV and lots of keyloggers and other malicious code running.

When this kind of verifications are executing on the client side there is no guarantee that the outcome is correct (which is why certificate based authentication is prefered as one of the factors since you can assure that it’s your internal device)

In this example there was a client side verification which was querying  (amongst other things) a file on the local system.

The endpoint compliancy failed due to some security setting

Remediation required

Let’s do the same thing again with procmon running

The service tries to query for a file in the c:\windows\system32 folder xxx.dll

So we create an empty dummy file, xxx.dll.

When we try to connect again with process monitor running we have a different result.

And we are prompted for user name and password, and hopefully this customer has an extra factor of protection, like SMS or certificate

Certificate is the best way to verify a device, to verify a user it depends on your identity management and how you choose to manage the identities and how to verify them