Monthly Archives: December 2020

US Agencies and FireEye Were Hacked Using SolarWinds Software Backdoor

Multiple news sources are attributing the recent breaches (FireEye, the U.S. Treasury, and the U.S. Commerce Departments) to the same group: ATP29 Cozy Bear. The type of attack used is called a supply chain attack where a software vendor is targeted in order to breach the end-customer of that software. In this case, it was SolarWinds’ Orion Network Monitoring Software, which said their March and June 2020 software releases were compromised. Microsoft researchers have observed two files in October 2019 with code anomalies in the SolarWinds DLL, so it is possible that the initial access into SolarWinds may have occurred six months or longer before the malicious updates started spreading. The company estimates 18,000 of its 300,000+ customers may have installed the malicious update (this would make it the 2nd largest in history behind Citrix who had a similar attack happen to them with their install base of 400,000 customers – more on that later). SolarWinds is used by all five branches of the U.S. military, the Pentagon, State Department, Justice Department, NASA, the Executive Office of the President, the National Security Agency, the top 10 U.S. telecommunications companies, and 425 of the Fortune 500.
[Update 12/18/2020 So far Microsoft has identified 40 customers who may have been impacted, including Microsoft itself].
[Update 12/20/2020 A Chinese group called RedDrip posted on Twitter that they decoded the dynamically generated domain names that this malware used to communicate with C2, revealing the customer names that were hit. Others have used their code to post the customer lists on Pastebin (here and here).]

An emergency directive issued by the U.S. government agency Cybersecurity and Infrastructure Security Agency (CISA) calls on all federal civilian agencies to disconnect or power down SolarWinds Orion IT management tools because they are being used to facilitate an active exploit. Everyone else would be wise to follow this guidance too. CISA encourages affected organizations to read the SolarWinds and FireEye advisories for more information and FireEye’s GitHub page for detection countermeasures.

The Microsoft advisory from 12/13/2020 adds “if you suspect you are impacted you should assume your [email] communications are accessible to the actor” because the techniques observed including modifications to authentication to give persistence to email in Exchange Online, with clever techniques: “By impersonating existing applications that use permissions like Mail.Read to call the same APIs leveraged by the actor, the access is hidden amongst normal traffic.” Attackers apparently exported the private key from the ADFS token signing certificate and used that to forge SAML to gain access to cloud apps and on-premises resources. Therefore, if you use ADFS, you should consider changing the token signing certificate, or follow NSA’s recommendation to use Azure as the IDP instead of ADFS.

These supply chain attacks are not uncommon. In March of 2019 the FBI informed Citrix that they had been infiltrated for five months, as reported by Brian Krebs. In 2013, the US retailer Target was thought to be breached by a supply chain attack involving their HVAC system. In the Wipro’s data breach, hackers used ScreenConnect (ConnectWise) to gain access to their customer systems. NotPetya gained access through the accounting software M.E.Doc.

Since Microsoft’s Office 365 email may have been “an attack vector” used by the hackers, be sure to watch our best practices webinar series to secure your Office 365 environments. This is especially important if you are a software vendor for now obvious reasons, hackers want to use you to get into your customer installation base.

Always Assume Breach

Supply chain attacks highlight an important security principle: You should always assume that you have already been breached. For most organizations, it is not practical to review software update, nor would you have the original source code anyway. It’s better to just assume you have already been breached and adopt a mindset to always be ‘hunting’ for intruders. The attackers used signed binaries using Symantec certificate with thumbprint: 0fe973752022a606adf2a36e345dc0ed, meaning application control solutions that block unsigned executables would not have blocked the malicious backdoor from executing. According to this SANS video discussing the attack, the SolarWinds backdoor waits 12 to 14 days before sending its first beacon, presumably to avoid anti-malware sandbox detection or network-based behavioral learning periods.

Microsoft provides several tools that detect anomalous behavior, and provide hunting tools, including:  Azure Sentinel, Microsoft Defender for Endpoint, Microsoft Defender for Identity, and Microsoft Cloud App Security.
Note: Microsoft has already updated Microsoft Defender to detect the malicious code in the SolarWinds Orion product as “Trojan:MSIL/Solorigate.B!dha”.  My former colleague Matthew Dowst wrote a few hunting queries to detect the modifications to federation trusts and oAuth. [Update 1/4/2021]  CISA has published a tool to automate the detection (here). The issue is that the audit logs only go back so far (90 days unless Advanced Audit license was enabled).

[Update 12/23/20] For customers who had their Azure logs backing up to a Log Analytics (aka Azure Monitor) workspace then there is a new workbook that can help identify if suspicious activity in the tenant occurred.

  1. Modified application and service principal credentials/authentication methods
  2. Modified federation settings
  3. Azure AD STS Refresh token modifications by service principals and applications other than DirectorySync
  4. New permissions granted to service principals
  5. Directory role and group membership updates for service principals

Reference: Azure AD workbook to help you assess Solorigate risk – Microsoft Tech Community

[Update 12/24/2020] Just stumbled on this new guidance for Incident Responders from Microsoft here:

Advice for incident responders on recovery from systemic identity compromises – Microsoft Security

Includes some very helpful O365 forensic tools such as Hawk.

Need Help?

If you need expert assistance hardening Office 365, send us a request and we would be glad to help. Email us at Secure365 at

Does Defender scan USB drives?

No, not by default. But this isn’t as bad as it sounds! Here is Microsoft’s explanation from ~four years ago:

“Historically, antivirus products had a function to scan all files when a removable device was mounted. However, with the increase in device storage capacity, full scans of removable devices can noticeably and severely impact performance. Today, Windows Defender Antivirus performs quick scans on the contents of removable devices (such as USB drives), before the contents are copied, or executed. This approach both mitigates the risk that a malicious threat can infect the host through a removable device, while maintaining host performance. (A dormant file on a removable drive cannot infect a host). However, if needed, Windows Defender Antivirus can be configured to perform a custom scan on all files when removable devices are mounted. Below is a sample script for achieving this scenario Reference: TechNet Custom scan a USB drive (

And a more recent, albeit abbreviated explanation from November 2020:

“You can optionally run a PowerShell script to perform a custom scan of a USB drive after it is mounted, so that Microsoft Defender Antivirus starts scanning all files on a removable device once the removable device is attached. However, we recommend enabling real-time protection for improved scanning performance, especially for large storage devices. Reference: How to control USB devices and other removable media using Intune (Windows 10) – Windows security | Microsoft Docs

I tested the “scanusb.ps1” script and it failed to detect the sample malware file on a USB Drive.




Also, the CPU spiked to 13% for the duration of the scan on the large drive.


But as soon as you attempt to interact with the file then its immediately caught by the AV engine:


Also, be aware that The default behavior for scheduled scans is to not scan removable media. You can enable it with Group Policy or running this confusing double-negative PowerShell command: set-MpPreference -disableRemovabledrivescanning $false

Therefore, I agree with Microsoft with this design decision and I will be guiding my clients to stick with the defaults which protect the machine from malware while avoiding costly CPU hits. 

Defender for Endpoint (MDATP) for Windows Servers

[Update: 10/7/2021] Microsoft released to public preview a unified installer so that Windows Server 2012 R2 and 2016 now have a single installer for both AV and EDR. The prerequisite is to deploy MS KB5005292 first.
Read the announcement here:

Microsoft Defender for Endpoint (MDE) supports four versions of Windows Server: 2008 R2, 2012 R2, 2016, and 2019*

Windows Server 2016 was the first version of Windows to feature native antivirus protection “for free”. It was then called Windows Defender AV and is now called Microsoft Defender AV. This is not to be confused with what was then called Advanced Threat Protection (WDATP or MDATP), and what was recently renamed Microsoft Defender for Endpoint. Back then the ATP added Endpoint Detection and Response (EDR) on top of the AV/EPP. And it was originally available through a separate “Azure Security Center” (ASC) subscription for approximately $15/server/month. However in 2020, Microsoft began to sell EDR for servers for $4.99/server/month (I believe the minimum QTY is 50 servers, contact a MSFT CSP or License Reseller for an exact quote). Note: At the Ignite 2020 conference, Microsoft rebranded parts of Azure Security Center to “Azure Defender” (reference).

But what if you needed a antivirus for earlier versions of server operating systems such as 2012 R2 or 2008 R2? Back then your option was System Center Endpoint Protection (SCEP), or if it is hosted in Azure you can deploy the free “Microsoft Antimalware for Azure” (MAA) which is the same antimalware platform that SCEP uses. The SCEP AV client is managed  with Group Policy or SCCM. See Yong Rhee’s blog here for more details on down-level client management (I included some details from his blog in the management section below).

There are three unique deployment scenarios for protecting Windows Server Operating Systems:




2008 R2 Yes Yes (N/A)
2012 R2 Yes Yes (N/A)
2016 No Yes Natively Installed
2019 No No Natively Installed

Scenario 1) Windows Server 2008 R2 and 2012 R2.

Separate deployment of SCEP (or MAA) (to get AV and EPP), and then the Microsoft Management Agent (MMA) to get EDR from the Microsoft Defender for Endpoint management console (

System Center Endpoint Protection (SCEP) can either be  distributed using GPO, System Center Configuration Manager (SCCM), or any software distribution tool of choice. SCCM is not a requirement to use SCEP but you must have access to the Endpoint Protection client installation package, scepinstall.exe. Find this package in the Client folder of the Configuration Manager installation folder on the site server.

Microsoft Defender for Endpoint (formerly known as MDATP) provides the EDR agent (aka MMA, or Microsoft Management Agent) and you would distribute this using SCCM, Group Policy, or your software distribution tool of choice.

The MMA agent has a prerequisite hotfix which should be on your servers if you apply all recommended updates. If you have some older servers that are infrequently patched, be sure to install the prerequisite hotfix (here).

MAA for Azure virtual machines offers a lightweight management option when first deploying to servers, with no central management, so its something to consider perhaps for a DMZ.


Scenario 2) Windows Server 2016

No need to deploy SCEP because Defender AV is natively built-in.

But you must deploy MMA either through Azure Defender or Microsoft Defender for Endpoint management console ( > Settings > Onboarding.

Scenario 3) Windows Server 2019

No need to deploy SCEP because Defender AV is natively built-in.

No need to deploy MMA, because EDR is natively built-in.  Since there is no MMA to deploy, Azure Defender (aka Azure Security Center) does not automatically onboard Windows Server 2019, and therefore it is mandatory at the time of this writing to onboard using the instructions in Microsoft Defender for Endpoint management console ( > Settings > Onboarding.

Microsoft Defender AV Management Settings

In Windows 10, Windows Server 2016, and Windows Server 2019, use the Group Policy (GPO) :

Computer Configuration –> Administrative Templates –> Windows Components –> Windows Defender Antivirus

This modifies the following registry key: Hkey_Local_Machine > Software > Policies > Microsoft > Windows Defender

However, in Windows Server 2012 R2, Windows 8.1, Windows Server 2012, Windows 8, Windows Server 2008 R2 SP1, Windows 7 SP1, Windows Server 2008 SP2, Windows Vista, you use a non-existent Group Policy (GPO):

Computer Configuration –> Administrative Templates –> Windows Components –> Endpoint Protection

This modifies the following registry key: Hkey_Local_Machine > Software > Policies > Microsoft > Microsoft Antimalware

So how do you get “Endpoint Protection” to show up? For this, see the procedure here: Manage Endpoint Protection using Group Policies – Configuration Manager | Microsoft Docs

Some IT Departments do not run traditional “AV” or “EPP” on their Windows Servers. They have their reasons, but its typically based on a threat model where if a strong firewall is deployed on server to prevent inbound communications, then the theory is that threats shouldn’t wind up on the server. The issue with this is GPO and other software distribution tools – you want some layered option to block threats from getting distributed via alternate means. So I do recommend SCEP for down-level servers.


*Server 2019 is also known as Long-Term Service Channel (LTSC). While MDE also supports the Semi-Annual Channel (SAC) versions of Windows Server, it is beyond the scope of this blog article to discuss the pros and cons of SAC (instead refer to Comparison of Windows Server Servicing Channels).