Attack using dot-dot-slash sequences is known as what?

Attack using dot-dot-slash sequences is known as what?

• A. SQL Injection
• B. Directory traversal
• C. XSS attack
• D. File injection

Answer: (B)

Path traversal relies on dot-dot-slash sequences to move up the directory tree when a program builds a file path from user input. If the server doesn’t properly sanitize and canonicalize that input, an attacker can craft something like ../../../../etc/passwd or its URL-encoded form to reach files outside the intended directory and read or manipulate them. This specific technique aims to access restricted files on the server, which is the essence of a directory traversal attack. It’s distinct from SQL Injection, which targets the database by manipulating SQL queries; from XSS, which injects scripts to run in a user’s browser; and from file injection, which is about placing or uploading files rather than traversing directories to access existing ones. To defend, validate and canonicalize all user-supplied paths, use realpath or safe path resolution, implement strict allowlists, and limit what the server can access through proper permissions and isolation.

Path traversal relies on dot-dot-slash sequences to move up the directory tree when a program builds a file path from user input. If the server doesn’t properly sanitize and canonicalize that input, an attacker can craft something like ../../../../etc/passwd or its URL-encoded form to reach files outside the intended directory and read or manipulate them. This specific technique aims to access restricted files on the server, which is the essence of a directory traversal attack.

It’s distinct from SQL Injection, which targets the database by manipulating SQL queries; from XSS, which injects scripts to run in a user’s browser; and from file injection, which is about placing or uploading files rather than traversing directories to access existing ones. To defend, validate and canonicalize all user-supplied paths, use realpath or safe path resolution, implement strict allowlists, and limit what the server can access through proper permissions and isolation.