Jan 01

Attack Methods for Gaining Domain Admin Rights in Active Directory

There are many ways an attacker can gain Domain Admin rights in Active Directory. This post is meant to describe some of the more popular ones in current use. The techniques described here “assume breach” where an attacker already has a foothold on an internal system and has gained domain user credentials (aka post-exploitation).

The unfortunate reality for most enterprises, is that it often does not take long from an attacker to go from domain user to domain admin. The question on defenders’ minds is “how does this happen?”.

The attack frequently starts with a spear-phishing email to one or more users enabling the attacker to get their code running on a computer inside the target network. Once the attacker has their code running inside the enterprise, the first step is performing reconnaissance to discover useful resources to escalate permissions, persist, and of course, plunder information (often the “crown jewels” of an organization).

While the overall process detail varies, the overall theme remains:

  • Malware Injection (Spear-Phish, Web Exploits, etc)
  • Reconnaissance (Internal)
  • Credential Theft
  • Exploitation & Privilege Escalation
  • Data Access & Exfiltration
  • Persistence (retaining access)

We start with the attacker having a foothold inside the enterprise, since this is often not difficult in modern networks. Furthermore, it is also typically not difficult for the attacker to escalate from having user rights on the workstation to having local administrator rights. This escalation can occur by either exploiting an unpatched privilege escalation vulnerability on the system or more frequently, finding local admin passwords in SYSVOL, such as Group Policy Preferences.

I spoke about most of these techniques when at several security conferences in 2015 (BSides, Shakacon, Black Hat, DEF CON, & DerbyCon).

I also covered some of these issues in the post “The Most Common Active Directory Security Issues and What You Can Do to Fix Them“.

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
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Oct 14

The Most Common Active Directory Security Issues and What You Can Do to Fix Them

The past couple of years of meeting with customers is enlightening since every environment, though unique, often has the same issues. These issues often boil down to legacy management of the enterprise Microsoft platform going back a decade or more.

I spoke about Active Directory attack and defense at several security conferences this year including BSides, Shakacon, Black Hat, DEF CON, and DerbyCon. These talks include information about how to best protect the Active Directory enterprise from the latest, and most successful, attack vectors.

While the threats have changed over the past decade, the way systems and networks are managed often have not. We continue with the same operations and support paradigm despite the fact that internal systems are compromised regularly. We must embrace the new reality of “Assume Breach.”

Assume breach means that we must assume that an attacker has control of a computer on the internal network and can access the same resources the users who have recently logged on to that computer has access to.
Note that when I describe risks and mitigations of Active Directory,this includes overall enterprise configuration.

Here are some of the biggest AD security issues (as I see them). This list is not complete, but reflects common enterprise issues.
I continue to find many of these issues when I perform Active Directory Security Assessments for organizations.

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


May 01

BSides Charm (2017) Talk Slides Posted – Detecting the Elusive: Active Directory Threat Hunting

I recently presented my talk  “Detecting the Elusive: Active Directory Threat Hunting” at BSides Charm in Baltimore, MD.
Slides are now posted in the Presentations section.

I cover some of the information I’ve posted here before:

 

On Sunday, April 30th, 2017, I spoke at BSides Charm in Track 2 at 2pm.

Here’s the talk description from the BSides Charm website:

Detecting the Elusive: Active Directory Threat Hunting
Attacks are rarely detected even after months of activity. What are defenders missing and how could an attack by detected?

This talk covers effective methods to detect attacker activity using the features built into Windows and how to optimize a detection strategy. The primary focus is on what knobs can be turned and what buttons can be pushed to better detect attacks.

One of the latest tools in the offensive toolkit is “”Kerberoast”” which involves cracking service account passwords offline without admin rights. This attack technique is covered at length including the latest methods to extract and crack the passwords. Furthermore, this talk describes a new detection method the presenter developed.

The attacker’s playbook evolves quickly, defenders need to stay up to speed on the latest attack methods and ways to detect them. This presentation will help you better understand what events really matter and how to better leverage Windows features to track, limit, and detect attacks

This presentation covers the type of log data required to properly

For the curious, here’s an outline of the talk:

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


May 01

Sp4rkCon (2017) Talk Slides Posted – Active Directory Security: The Good, the Bad, & the UGLY

I recently presented my talk “Active Directory Security: The Good, the Bad, & the UGLY” at Sp4rkCon in Bentonville, AR in April 2017.
Slides are now posted in the Presentations section.

I cover some of the information I’ve posted here before:

Here’s the talk description:

Active Directory Security:The Good, the Bad, & the UGLY

While security of the enterprise has been laid bare for years, exploitation techniques targeting  Active Directory were relatively rare. In recent years, attackers have focused on more than passing hashes and getting Domain Admin. From SPN Scanning for services to Kerberoasting for credentials to Golden Tickets for persistence, there are multiple methods for attacking Active Directory. Active Directory is the primary identity and management infrastructure for most enterprises and properly securing the AD forest has never been more important.

Some of the topics covered:

* PowerShell attacks

* Active Directory recon

* Credential theft

* Kerberos delegation

This talk is an update of Sean’s talk from 2015 entitled: “Red vs. Blue:
Modern Active Directory Attacks & Defense” where he covered various attack methods and related mitigation. This update explores the current attack techniques and the latest detection.

The presented Information is useful for both Red & Blue Team members.

This presentation is a remix of talks I did last year with some additional information mixed in. New to this talk is coverage of Kerberos delegation issues (not just unconstrained) and how to detect Kerberoasting.

For the curious, here’s an outline of the talk:

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


Feb 05

Detecting Kerberoasting Activity

Introduction

Kerberoasting can be an effective method for extracting service account credentials from Active Directory as a regular user without sending any packets to the target system. This attack is effective since people tend to create poor passwords. The reason why this attack is successful is that most service account passwords are the same length as the domain password minimum (often 10 or 12 characters long) meaning that even brute force cracking doesn’t likely take longer than the password maximum password age (expiration). Most service accounts don’t have passwords set to expire, so it’s likely the same password will be in effect for months if not years. Furthermore, most service accounts are over-permissioned and are often members of Domain Admins providing full admin rights to Active Directory (even when the service account only needs to modify an attribute on certain object types or admin rights on specific servers).

Tim Medin presented on this at DerbyCon 2014 in his “Attacking Microsoft Kerberos Kicking the Guard Dog of Hades” presentation (slides & video) where he released the Kerberoast Python TGS cracker.

This is a topic we have covered in the past in the posts “Cracking Kerberos TGS Tickets Using Kerberoast – Exploiting Kerberos to Compromise the Active Directory Domain” & “Sneaky Persistence Active Directory Trick #18: Dropping SPNs on Admin Accounts for Later Kerberoasting.”
Also Will Schroeder, aka Will Harmjoy (@harmj0y), and I spoke at DerbyCon 2016 about how to Kerberoast to escalate privileges.

Note: This attack will not be successful when targeting services hosted by the Windows system since these services are mapped to the computer account in Active Directory which has an associated 128 character password which won’t be cracked anytime soon.

Let’s quickly cover how Kerberos authentication works before diving into how Kerberoasting works and how to detect Kerberoast type activity.

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


Jan 29

Sneaky Persistence Active Directory Trick #18: Dropping SPNs on Admin Accounts for Later Kerberoasting

The content in this post describes a method through which an attacker could persist administrative access to Active Directory after having Domain Admin level rights for about 5 minutes.

Complete list of Sneaky Active Directory Persistence Tricks posts

This post explores how an attacker could leverage existing admin rights and/or over-permissive delegation to gain persistence on an admin account or accounts..

Any account with a Service Principal Name can be Kerberoasted. It’s possible with the appropriate rights to add SPNs to accounts, including admin accounts, to discover the password for those accounts in order to gain/re-gain access to the account.

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


Nov 03

Securing Domain Controllers to Improve Active Directory Security

Active Directory security effectively begins with ensuring Domain Controllers (DCs) are configured securely. At BlackHat USA this past Summer, I spoke about AD for the security professional and provided tips on how to best secure Active Directory. This post focuses on Domain Controller security with some cross-over into Active Directory security. The blog is called ADSecurity after all… 😉

This post covers some of the best methods to secure Active Directory by securing Domain Controllers in the following sections:

  • Default Domain & Domain Controller Policies
  • Creating Domain & Domain Controller Security Baseline GPOs
  • Patching Domain Controllers
  • Protecting Domain Controllers
  • Domain Controller Recommended Group Policy Settings
  • Configuring Domain Controller Auditing (Event Logs)
  • Domain Controller Events to Monitor (Event Logs)
  • Key Domain Controller Security Items

As with any major change to infrastructure, please test before deploying changes.

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


Oct 18

BSides DC (2016) Talk – PowerShell Security: Defending the Enterprise from the Latest Attack Platform

This Saturday at BSides DC, I am presenting on the current state of PowerShell security in a talk called, “PowerShell Security: Defending the Enterprise from the Latest Attack Platform.”

I cover some of the information I’ve posted here before:

On Saturday, October 21st, 2016, I am speaking at BSides DC in Track 2 (“Grand Central”) at 1:30pm.

Here’s the talk description from the BSides DC website:

PowerShell is a boon to administrators, providing command consistency and the ability to quickly gather system data and set configuration settings. However, what can be used to help, can also be used for less altruistic activities. Attackers have recently learned that leveraging PowerShell provides simple bypass methods for most defenses and a platform for initial compromise, recon, exploitation, privilege escalation, data exfiltration, and persistence.

With the industry shift to an “Assume Breach” mentality, it’s important to understand the impact of defending against an attacker on the internal network since this is a major shift from the traditional defensive paradigm. In its default configuration, there’s minimal PowerShell logging and nothing to slow an attacker’s activities. Many organizations seek to block the PowerShell executable to stop attacks. However, blocking PowerShell.exe does not stop PowerShell execution and can provide a false sense of security. Simply put, don’t block PowerShell, embrace it. The key is monitoring PowerShell usage to enable detection of recon and attack activity. As attack tools like PowerSploit (Invoke-Mimikatz) and the recently released PowerShell Empire become more prevalent (and more commonly used), it’s more important than ever to understand the full capabilities of PowerShell as an attack platform as well as how to effectively detect and mitigate a variety of PowerShell attack methods.

The presentation walks the audience through the evolution of PowerShell as an attack platform and shows why a new approach to PowerShell attack defense is required. PowerShell recon & attack techniques are shown as well as methods of detection & mitigation. Also covered are the latest methods to bypass and subvert PowerShell security measures including PowerShell v5 logging, constrained language mode, and Windows 10’s AMSI anti-malware for scanning PowerShell code in memory.The final part of the presentation explains why PowerShell version 5 should be every organization’s new baseline version of PowerShell due to new and enhanced defensive capability.

This talk is recommended for anyone tasked with defending and testing the defenses for an organization as well as system administrators/engineers.

This presentation outlines that capability of the current PowerShell version and how current attacks are leveraging PowerShell, including how current PowerShell security (& logging) can be bypassed!
The talk wraps up with a summary of the defensive recommendations provided throughout the presentation.

For the curious, here’s an outline of the talk*:

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


Sep 27

Some Favorite DerbyCon 6 Talks (2016)

This post is a collection of my favorite and interesting talks from DerbyCon 6 (2016). There were a lot of great talks and as I discover them, I’ll add them here. My goal is to collect and provide the talk videos and slides together for a single, easy reference. I’m sure I missed a few.
To read about the DerbyCon 6 presentations visit the DerbyCon 6 Schedule page and the DerbyCon 6 presentation videos are on YouTube.

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


Sep 13

DerbyCon 6 (2016) Talk – Attacking EvilCorp: Anatomy of a Corporate Hack

Next week at DerbyCon 6, Will Schroeder (aka Will Harmjoy, @Harmj0y) & I are presenting on enterprise security, “Attacking EvilCorp: Anatomy of a Corporate Hack.”
We call this one the “How You Got Hacked” presentation.

The company and events are fictional.

The techniques are real.

On Saturday, September 24th, 2016, Will & I are speaking at DerbyCon Track 1 (Break Me) in the Regency North room from 10:00am to 10:50am.

Here’s the talk description from the DerbyCon website:

With the millions of dollars invested in defensive solutions, how are attackers still effective?
Why do defensive techniques seem to rarely stop or slow down even mid-tier adversaries?
And is there anything the underfunded admin can do to stop the carnage?
Join us in a shift to “assume breach” and see how an attacker can easily move from a single machine compromise to a complete domain take over.
Instead of “death by PowerPoint,” see first-hand how a fictional corporation suffers “death by a thousand cuts”. The fictional EvilCorp presents their top defensive tools and practically dares someone to attack the network. The battle of Red vs. Blue unfolds showing EvilCorp’s network submit to the unrelenting attacks by an experienced adversary.
When the dust settles, the Red Team looks victorious. But what, if anything, could have tipped the scales in the other direction?
In this demo-heavy session (several demos are shown to demonstrate modern attack effectiveness), we showcase the latest attack techniques and ineffective defenses still used to protect companies. Defense evasion tools and techniques are detailed as well as attack detection methods. Effective mitigation strategies are highlighted and the Blue Team is provided a roadmap to properly shore up defenses that can stop all but the most determined attacker.

This presentation is not a standard conference talk with lots of slides. In fact, there are only a handful of slides, mostly to highlight how to mitigate the demonstrated attacks. Over the course of the 45 minute presentation, we show several attack demonstrations highlighting typical phases of how a company could be hacked and talk through the issues in the environment and real world mitigations. Instead of walking through the attacks and showing slides, we present this as a “skit”.

During the talk, Sean assumes the role of E Corp CIO who is on stage at a conference presenting about their perfect security. He effectively challenges the world to hack his company.

Will takes up this challenge and explains the problems with E Corp’s security posture by showing several demos how he can pwn them in about 25 minutes.

After this “skit”, we switch back to more traditional presentation to cover real-world mitigations.

For the curious, here’s an outline of our talk at DerbyCon next week:

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Trimarc helps companies and organizations improve their security to better protect against and detect attacks.
Visit TrimarcSecurity.com for more information.


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