Explain directory transversal attacks ?

Directory traversal attacks, also known as path traversal attacks or directory climbing attacks, are a type of security vulnerability that allows an attacker to access files and directories that are outside of the web server's root directory. This can potentially give the attacker access to sensitive information, such as configuration files, user data, or even system files.

These attacks typically occur when a web application does not properly validate user input, such as file paths or URLs. By manipulating the input, an attacker can navigate through the file system and access files that they should not have access to.

To prevent directory traversal attacks, developers should always validate and sanitize user input, especially when dealing with file paths or URLs. It is also recommended to use whitelists instead of blacklists when defining acceptable input, as blacklists can be easily bypassed by attackers. Additionally, restricting file permissions and using secure coding practices can help mitigate the risk of directory traversal attacks.