Today Cyber Security plays a paramount role in global security. On this blog, the CEO of Paramount Defenses shares rare insights on issues related to Cyber Security, including the World's Top Cyber Security Risk, Advanced Persistent Threats (APT), Cyber Warfare, Corporate Espionage, Insider Threats and other topics.

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July 3, 2018

Mimikatz DCSync Mitigation


A few days ago I asked a (seemingly) very simple question ; no I'm not referring to this one, I'm referring to this one here  -

Can Anyone (i.e. any Cyber Security Company or Expert) Help Thousands of Microsoft's Customers MITIGATE the Risk Posed by Mimikatz DCSync?

Here's why I did so - While there's a lot of info out there on the WWW about how to use Mimikatz DCSync, and/or how to detect its use, there isn't one other* single correct piece of guidance out there on how to mitigate the risk posed by Mimkatz DCSync.

So, as promised, today I am (literally) going to show you exactly how thousands of organizations worldwide can now easily and demonstrably actually mitigate the very serious cyber security risk posed to their foundational security by Mimikatz DCSync.

In light of what I've shared below, organizations worldwide can now easily mitigate the serious risk posed by Mimikatz DCSync.

First, A Quick Overview

For those who may not know, and there are millions who don't, there are three quick things to know about Mimikatz DCSync.

Mimikatz DCSync, a Windows security tool, is the creation of the brilliant technical expertise of Mr. Benjamin Delpy, whose work over the years has very likely (caused Microsoft a lot of pain ;-) but/and) helped substantially enhance Windows Security.

Mimikatz DCSync targets an organization's foundational Active Directory domains, and instantly gives any attacker who has sufficient privileges to be able to replicate sensitive content from Active Directory, access to literally everyone's credentials!

Thus far, the only guidance out there is on how to DETECT its use, but this is one of those situations wherein if you're having to rely on detection as a security measure, then its unfortunately already TOO late, because the damage has already been done.

Detection Is Hardly Sufficient

They say a picture's worth a thousand words, so perhaps I'll paint a picture for you. Relying on detection as a security measure against Mimikatz DCSync is akin to this -

Castle romeo2

Lets say a nuclear weapon just detonated in a city, and the moment it did, detection sensors alerted the city officials about the detonation. Well, within the few seconds in which they received the alert, the whole city would've already been obliterated i.e. by the time you get the alert, literally everyone's credentials (including of all privileged users) would've already been compromised!

Make not mistake about it - a single successful use of Mimikatz DCSync against an organization's foundational Active Directory domain is tantamount to a complete forest-wide compromise, and should be considered a massive organizational cyber security breach, the only way to recover from which is to completely rebuild the entire Active Directory forest from the ground up!

This is why detection is grossly insufficient as a security measure, and what organizations need is the ability to prevent the use of Mimikatz DCSync's against their foundational Active Directory domains & thus the ability to mitigate this risk is paramount.

How to Mitigate Mimikatz DCSync

The key to mitigating this risk lies in identifying what it technically takes to be able to successfully use Mimikatz DCSync.

Specifically, if you know exactly what privileges an attacker needs to be able to successfully use Mimikatz DCSync against your Active Directory domain, then by ensuring that only highly-trustworthy, authorized individuals (and not a single other individual) actually currently possess those required privileges in your IT infrastructure, you can easily mitigate this risk.

Technically speaking, all that an attacker needs to successfully use Mimikatz DCSync is sufficient Get Replication Changes All effective permissions on the domain root object of an Active Directory domain, so all that organizations need to do is accurately identify exactly who has these effective permissions on the domain root object of each of their Active Directory domains.

While by default only the default administrative Active Directory security groups are granted this permission, since most Active Directory deployments have been around for years, and have likely gone through a substantial amount of access provisioning, in most Active Directory, a lot many more individuals than merely the members of the default AD admin groups may likely have this highly sensitive effective permission granted to them, either directly or via group membership, some of which may be direct, whilst others may be via nested group memberships, resulting in a potentially large and unknown attack surface today.

Now, it is paramount to understand ONE subtle but profound difference here - it is NOT who has what permissions on the domain root that matters, but who has what effective permissions on the domain root that matters, and this difference could be the difference between a $100 B organization being completely compromised or being completely protected from compromise.

The Key - Active Directory Effective Permissions

If you've followed what I've shared above, then you'll agree and understand that the key to being able to successfully mitigate the serious risk posed by Mimikatz DCSync lies in being able to accurately determine effective permissions in Active Directory.

In fact Effective Permissions are so important, essential and fundamental to Windows and Active Directory Security, that of the four tabs in all of Microsoft's Active Directory Management Tooling, one entire tab is dedicated to Effective Permissions.

Unfortunately, it turns out that not only is Microsoft's native Effective Permissions Tab not always accurate, it is substantially inadequate, and while I could elaborate on that, I'd rather let you come to the same conclusion yourself, and this ONE glaring inadequacy will be self-evident the moment you attempt to use it to try and find out exactly whom amongst the thousands of domain user account holders in your Active Directory domain(s), actually has the required effective permissions. In fact, the same is true of all tools/scripts that involve the use of Microsoft's APIs to do so, such as this dangerously inaccurate free tool.

Fortunately, in a world whose population is 7,000,000,000+ today, thanks to one (1) inconsequential individual, there's hope...

Finally, How to Easily and Reliably Mitigate the Risk Posed by Mimikatz DCSync

Here's a very short (and perhaps boring but insightful) video on how organizations worldwide can reliably mitigate this risk -

Note: This is NOT intended to demonstrate our unique tooling. It is solely intended to show what it takes to mitigate this serious risk. We have no particular interest in licensing our unique tooling to anyone. As such, over the years, we have NEVER, not once pitched our tooling to anyone; we've had almost 10,000 organizations worldwide knock at our doors completely unsolicited, so I hope that makes this point unequivocally.

Thus, as seen in the short video above, with the right guidance (knowledge) and capability (tooling), organizations worldwide can now easily and reliably mitigate the serious cyber security risk posed by Mimikatz DCSync to their foundational security.

Complete, illustrated, step-by-step details on how to easily and correctly mitigate Mimikatz DCSync can now be found here.

I'll say this one last time - a single successful use of Mimikatz DCSync against an organization's foundational Active Directory is tantamount to a forest-wide compromise and constitutes a massive cyber security breach, which is why mitigation is paramount.

Best wishes,

PS: *Here are 4 posts I've previously penned on Mimikatz DCSync - a summary, technical details, a scenario and the question.

PS2: In days to come, I'll answer this question too.