Group3r - An Active Directory Enumeration Tool For Pentesters And Red Teamers

Group3r is a powerful tool designed to assist penetration testers and red teamers in efficiently enumerating Active Directory (AD) Group Policy settings and identifying exploitable misconfigurations.

This guide will explain what Group3r does, why it was created, how to use it, and how to interpret its output.

What Does Group3r Do?

Group3r is specifically tailored for offensive security professionals. It interacts with AD environments to:

  • Enumerate Group Policy Objects (GPOs) and their associated settings.
  • Identify exploitable misconfigurations in GPOs.
  • Analyze files referenced within GPOs, such as scripts, MSI packages, or executables.
  • Parse GPO configuration files from the domain SYSVOL share.
  • Perform LDAP queries against Domain Controllers.

Unlike audit tools like Microsoft's Security and Compliance Toolkit, Group3r is not intended for compliance checks or policy audits. Instead, it focuses on uncovering attack paths and vulnerabilities that could be leveraged by adversaries.

Why Was Group3r Created?

Historically, offensive techniques targeting Group Policy have focused on:

  1. Extracting credentials (e.g., from Group Policy Preferences).
  2. Abusing weak Access Control Lists (ACLs) to modify GPOs.

While these techniques are valuable, they overlook other critical aspects of Group Policy that can reveal additional vulnerabilities or attack vectors. Group3r was developed to fill this gap by providing a broader analysis of GPOs.

Evolution of Group3r

  • Grouper (v1): Written in PowerShell but had significant limitations.
  • Grouper2: Rewritten in C#, but poorly implemented due to lack of programming experience.
  • Group3r: A complete rewrite in C# with improved usability, functionality, and stability.

How to Use Group3r

Basic Usage

Group3r requires you to specify an output method:

  • -s: Sends results to standard output (stdout).
  • -f group3r.log: Writes results to a file.

Note: If neither -s nor -f is specified, the tool will not run.

Targeting Specific Domains or Users

  • Run on a domain-joined machine as a domain user for best results.
  • For non-domain machines:
    • Use runas /netonly.
    • Specify the Domain Controller with -c $dcIpAddress.
    • Provide the domain name using -d domain.tld.

To simulate running as another user or group:

  • Use -u domain\user or specify a group in the same format.

Limiting Output

Group3r provides several options to filter its findings:

  • -w: Show only settings with associated findings (e.g., misconfigurations).
  • -a <severity>: Limit output to findings of a specific severity level (e.g., 4 for the highest severity).
  • -e: Display only enabled GPOs and settings.
    • Warning: Disabled settings may still contain valuable information like credentials.
  • -r: Exclude "morphed" files/folders created due to replication failures between Domain Controllers.

Offline Mode

If you have an offline copy of SYSVOL:

  • Use -o -y $pathToSysvol for limited analysis without live domain access.

Reading the Output

Group3r’s output highlights different components of GPOs using color-coded sections:

  1. Group Policy Object (GPO):
    • Displays the GPO name, unique identifier, and whether it is "current" or "morphed."
    • Includes basic information such as linked Organizational Units (OUs).
  2. Settings:
    • Indented under their associated GPO for clarity.
    • Indicates the type of setting (e.g., MSI package, script).
  3. Findings:
    • Highlighted in green with a triage level color-coded as:
      • Green: Low severity.
      • Yellow: Medium severity.
      • Red: High severity.
      • Black: Critical severity.
    • Provides details about the misconfiguration and potential abuse scenarios.

Examples

  1. MSI Package Setting:
    • A finding might indicate that an MSI package installs software vulnerable to exploitation.
  2. Startup Script Setting:
    • Findings could include:
      • Hardcoded passwords in script arguments.
      • Scripts modifiable by the current user, enabling privilege escalation.
  3. Morphed Files:
    • These are remnants from replication failures and may contain outdated but sensitive information like old credentials.

Key Considerations

  1. Disabled settings and morphed files can still contain valuable data—use filtering options judiciously.
  2. Always run Group3r within an appropriate legal and ethical framework; unauthorized use is prohibited.
  3. For compliance checks or security standards validation, use dedicated audit tools instead of Group3r.

By leveraging Group3r effectively, pentesters and red teamers can uncover hidden vulnerabilities in AD environments, expanding their arsenal of attack techniques while gaining deeper insights into organizational security postures. You can learn more and Download Group3r in GitHub.

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