Pablo Guides

# Passing-the-Hash: Advanced Techniques for Penetration Testing

## Introduction

In the world of penetration testing and cybersecurity, mastering the techniques used by attackers is paramount to developing effective defensive measures. One of the more notorious methods employed by malicious actors is "passing-the-hash," a technique that allows an attacker to authenticate to a network resource without needing to know the plaintext password. In this section, we will delve deeply into the mechanics of passing-the-hash, providing comprehensive guides on installation, configuration, usage, and real-world applications using Kali Linux.

## Installation and Configuration on Kali Linux

### Prerequisites

Before diving into the installation process, ensure your Kali Linux environment is up-to-date. You can update your system by running the following commands:

"`bash
sudo apt update
sudo apt upgrade
"`

### Installing Required Tools

The primary tool we'll utilize for passing-the-hash is `impacket`, a collection of Python classes focused on providing low-level access to network protocols. Here's how to install it:

1. **Install Git and Python**: If you haven't already, you'll need to install Git and Python:

   sudo apt install git python3 python3-pip

 

2. **Clone the Impacket Repository**:

   git clone https://github.com/SecureAuthCorp/impacket.git

 

3. **Install Impacket**:

Navigate to the impacket directory and install it using pip:

   cd impacket

   sudo pip3 install .

 

Now you have the core tools set up. You may also want to install other utilities that facilitate pentesting activities, such as `smbclient`, `smbmap`, and `netcat`.

### Configuration

After installing the necessary tools, make sure they are properly configured. Impacket provides a variety of scripts that you can use for passing-the-hash techniques.

Consider running the following command to list the available scripts in the impacket suite:

"`bash
ls /usr/local/bin | grep impacket
"`

You should see utilities like `wmic.py`, `psexec.py`, and others.

## Step-by-Step Usage and Real-World Use Cases

### Understanding Hashes

Before we begin using the tools, it is essential to understand how NTLM hashes function. When a user logs in, their password is transformed into an NTLM hash. For example, the plaintext password "password" would yield a different hash value via the NTLM hashing algorithm.

### Example Scenario: Gaining Access to a Remote Machine

In this example, we will simulate an ethical hacking scenario where we aim to access a Windows machine on the same network without having the plaintext password, utilizing a captured NTLM hash.

#### Step 1: Capturing the NTLM Hash

In a real-world scenario, the NTLM hash can be captured during a man-in-the-middle attack, through tools like `Responder` or `Metasploit`. However, for demo purposes, we will use an example hash.

Let's assume we have the NTLM hash for the username `admin` as follows:

"`
admin:500:3a5a5b4d5f7d8c0e49b2a2f123bc1e2b:1c9f5cf44f9b89937e7e0a66e3c9c78d:::
"`

Here, `3a5a5b4d5f7d8c0e49b2a2f123bc1e2b` is the hash we want to use for authentication.

#### Step 2: Using Pass-the-Hash with Impacket

With the hash in hand, we can now use the `psexec.py` script from the Impacket suite to authenticate against our target machine.

The command looks like this:

"`bash
python3 /path/to/impacket/examples/psexec.py admin:3a5a5b4d5f7d8c0e49b2a2f123bc1e2b@
"`

If successful, this should give you a command line shell on the target Windows machine.

### Real-World Use Case: Lateral Movement

Once you gain access to a device, you can move laterally through the network using the same technique. Capture hashes from one machine and use them against others.

### Additional Use Cases

– **Accessing Shared Drives**: Use `smbclient` to access shared drives on network locations where you possess the hash.
– **Extracting Information**: Dump password hashes from various applications or databases that store authentication information.

## Detailed Technical Explanations

### How NTLM Works

NTLM (NT LAN Manager) is a Microsoft authentication protocol that utilizes challenge-response authentication. Understanding its mechanics is crucial for exploiting or defending against passing-the-hash attacks.

1. The client sends a request for access.
2. The server responds with a challenge.
3. The client hashes the password (or uses NTLM hash) and returns the response to the server.
4. The server verifies the response and grants access.

### Security Implications

Passing-the-hash attacks exploit weaknesses in how NTLM hashes are stored and transmitted. By leveraging these weaknesses, an attacker can gain unauthorized access to network resources. Implementing best practices such as enforcing strong password policies, enabling account lockout policies, and using more secure authentication mechanisms (like Kerberos) can mitigate these risks.

### Additional Resources

– [Kali Linux Official Documentation](https://www.kali.org/docs/)
– [Impacket GitHub Repository](https://github.com/SecureAuthCorp/impacket)
– [Microsoft Security Guidance on NTLMv1](https://docs.microsoft.com/en-us/windows-server/security/kerberos/ntlm-security)

## Code Examples

Using passing-the-hash could be implemented in different scenarios:

### Capturing Hashes with Responder

"`bash
sudo python3 responder.py -I -wrf
"`

### Executing Commands on a Remote Machine

"`bash
python3 /path/to/impacket/examples/psexec.py administrator:[email protected] cmd.exe
"`

### Accessing SMB Shares

"`bash
smbclient //192.168.1.100/share -U admin%your_hash
"`

## Conclusion

Passing-the-hash is a powerful technique that showcases the importance of understanding the tools and methods used by attackers. Through this section, you've learned how to install, configure, and utilize Kali Linux tools to conduct pentesting operations with passing-the-hash techniques. As always, employ these skills ethically and responsibly, focusing on improving security and protecting systems from malicious threats.

—

Made by pablo rotem / פבלו רותם