Identify the attack when an attacker by several trial and error can read the contents...

Theattack described is a Directory Traversal Attack. This type of attack occurs when an attacker exploits vulnerabilities in a web application (or a web server’s software) to gain unauthorized access to files and directories that are stored outside of the web root folder. By manipulating variables that reference files with ../ sequences (also known as dot-dot-slash), the attacker can move up the directory hierarchy and access files or directories that should be restricted. This can lead to information disclosure, such as reading sensitive files like /etc/passwd, which contains user password details in Unix-based systems.

In the given URL http://www.terabytes.com/process.php./../../../../etc/passwd , the attacker uses the ../ pattern to navigate up from the current directory where process.php resides, aiming to reach the root directory and then descend into the /etc/ directory to access the passwd file. This is a classic example of a Directory Traversal Attack.