As defined by Wikipedia "Security testing is a process to determine that an information system protects data and maintains functionality as intended".

Today’s networks and infrastructures are typically comprised of a variety of components from many vendors. This increases the level of complexity faced by the system administrators, as they must familiarize themselves with specific security concerns created by each product, and remain current as new security flaws are discovered. Critical in this respect are also the in-house developed solutions where administrators and developers that usually don't have a strong security knowledge are faced with the challenge of making their applications resistant to known attacks.

NTT Security provides a wide range of security testing services to support it's customers in enhancing their overall level of security.