Attack Webforms with Beautifulsoup and Requests in Python

Introduction to Attacking Webforms

Web forms serve as the gateway for user interaction on a website. They are used in collecting user data, processing inquiries, and facilitating online transactions. Understanding their structure, functionality, and potential vulnerabilities is important for web developers, and security professionals.

Automating webforms involves the process of programmatically interacting with web pages to simulate user inputs and submissions. This automation is particularly valuable for a variety of purposes:

• Consistent data entry, saving considerable time and effort.
• Testing the functionality and resilience of web applications. By simulating user interactions, developers can identify and rectify issues in a controlled environment.
• Data extraction from websites, a critical function for web scraping, market research, and data analytics.
• Security professionals utilize automation to assess web application security.

Installing Requests and Beautiful Soup

Requests Library

The Requests library is an essential tool in Python for making HTTP requests. It simplifies the process of sending HTTP requests to web servers and handling their responses. Here are some key functionalities of Requests:

• Provides an easy-to-use API for sending various types of HTTP requests, including GET, POST, PUT, DELETE, and more.
• Provides built-in support for handling cookies and sessions.
• Allows custom headers in requests and supports various authentication methods.
• Features for uploading files to web servers and the downloading of content, making it useful for web scraping.

Beautiful Soup Library

Beautiful Soup is a powerful Python library designed for parsing HTML and XML documents. Here are the key functionalities of Beautiful Soup:

• Transforms raw HTML or XML content into a parse tree, enabling extraction of specific elements, such as tags, attributes, and text.
• Efficient traversal of the parse tree using methods like .find() and .find_all(), making it simple to locate specific elements based on tags, classes, IDs, and more.
• Permits the addition, removal, and modification of elements and their attributes.

Installing Steps

To set up a python environment and install the Requests and Beautiful Soup libraries, follow these steps:

1. Create a Virtual Environment:
   A virtual environment in Python is an isolated environment that allows you to install and manage packages separately from the system-wide Python installation, ensuring dependencies don't conflict across different projects.

   This command creates a new virtual environment named myenv.

2. Activate the Virtual Environment:
   Use the following command as per your OS to initialize the virtual environment.

   • On Windows:

   • On macOS and Linux:

3. Install Requests and Beautiful Soup:
   Pip is a Python package manager that allows you to easily install and manage libraries.

   This command installs both libraries within the virtual environment.

Collecting a Web Page with Requests

With the Requests library, you can effortlessly retrieve web pages, making them accessible for further analysis. Utilizing the power of HTTP requests, you can retrieve the HTML content of a webpage with just a few lines of Python code.

To demonstrate the process of collecting a web page using the Requests library, let's create a simple HTML page with a form:

Now, let's use the requests.get() method of the Requests library which allows you to send a GET request to a specified URL, enabling you to retrieve the content of a web page.

Output:

You can also customize the get() function with headings or timeouts by adding an extra parameter to the function. For instance, to add to a timeout of 5 seconds:

Similarly, the requests.post(url,body) method can be used to perform a POST request to the url with the body.

The response variable stores the response from the website and has various properties:

• status_code:
  The HTTP status code returned by the server. A status code of 200 indicates a successful request.
• headers:
  The headers sent by the server in the response. This includes information like content type, encoding, and more.
• text:
  Provides the response content as a string, assuming the content is text-based.
• content:
  Gives the raw response content in bytes.
• url:
  The final URL after any redirects.
• cookies:
  Holds any cookies sent by the server in the response.

As we have extracted the content from a web page, this content can now be parsed or further processed as needed.

Stepping Through a Page with Beautiful Soup

Having gathered the HTML content, the next step is to navigate through it effectively. This is where Beautiful Soup comes into play. Let us use the previous code and implement automation of form submission using beautiful soup.

Let us explore the functions used as part of the Beautify Soup Library:

• The BeautifulSoup function creates a parse tree for parsing the source code of an HTML where page_content is the raw HTML content of a webpage and html.parser is the parser that Beautiful Soup uses to interpret the HTML content.

The soup object created by this line allows us to navigate and manipulate the HTML structure of the webpage.

• soup.find():
  Find the first occurrence of an HTML tag or a CSS class. For example, soup.find('form') would locate the first <form> element on the page.
• soup.find_all():
  Find all occurrences of an HTML tag or CSS class.
• element.get():
  This method allows us to retrieve attributes of an HTML element.

The soup.prettify() is yet another function that can be used to pretty-print the HTML content, making it more human-readable. It formats the HTML with proper indentation and line breaks.

Output

Explanation:

1. The script fetches the HTML content of the sample form from the specified URL.
2. The content is then parsed using Beautiful Soup.
3. The script locates the form and retrieves its action and method attributes.
4. It iterates through the input fields, collecting their names and default values to create a payload.
5. You can add your desired data to the payload. In this example, we're filling out the username and password fields.
6. Finally, the script submits the form using a POST request.

This script simulates a user interacting with the form, making it a powerful tool for various web automation tasks.