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Directory Traversal Attacks Explanation

Directory Traversal Attack
A Directory Traversal attack, also known as Path Traversal or Directory Climbing, is a type of security vulnerability in which an attacker attempts to access files or directories that are outside of the intended directory structure. This attack takes advantage of improper input validation and can lead to unauthorized access to sensitive files or even system compromise. It commonly targets web applications and is often the result of insufficient input validation or inadequate access controls.

Types of Directory Traversal Attacks:

  • Basic Directory Traversal: The attacker tries to access files or directories by manipulating the path provided in a URL or input field. For example, if a web application allows users to download files by specifying a file name in the URL, an attacker may use "../" to move up the directory structure and access files outside of the intended directory.
  • Null Byte Attack: The attacker injects a null byte character ("%00") into the input to trick the application into ignoring everything after the null byte. This can be used to bypass security checks and access files outside the intended directory.

Example of a Directory Traversal Attack:

Let's say there's a web application that allows users to view files stored on the server by providing a file name in the URL, like this:

An attacker might try to perform a directory traversal attack by changing the filename parameter to something like:

If the application doesn't properly validate the input, it might allow the attacker to access sensitive system files like the "/etc/passwd" file.

File Inclusion Attack:
A File Inclusion attack occurs when an attacker is able to include or execute files from the server within a web application's code. This can lead to various security risks, including remote code execution, information disclosure, and application compromise. File Inclusion attacks often exploit web application vulnerabilities where user-controllable data is used to specify which files are included.

Types of File Inclusion Attacks:

  • Local File Inclusion (LFI): In LFI attacks, an attacker tries to include local files from the server. If the application allows user input to specify files, an attacker can manipulate the input to include sensitive files.
  • Remote File Inclusion (RFI): In RFI attacks, an attacker tries to include files hosted on remote servers. This can be especially dangerous, as it can lead to the execution of malicious code from a remote server.

Example of a File Inclusion Attack (Local File Inclusion):

Suppose a website includes user profile pages using a URL like:

An attacker might attempt a Local File Inclusion attack by manipulating the "user" parameter like this:

If the application doesn't validate the input properly, it might include the contents of the "/etc/passwd" file, exposing sensitive system information.

It's important for developers to implement input validation and access controls to prevent these types of attacks in their web applications.