What is Backdoor

Backdoor threats increase when multiuser and networking operating systems are used by many organizations. In a login system, a backdoor used for system access may be in the form of a hard-coded username and password.
A network administrator  may intentionally create or install a backdoor program for troubleshooting or other official use. Hackers use backdoors to install malicious software or programs, modify code or detect files and gain system and data access. Even backdoors installed by network administrators pose security risks because they provide a mechanism by which the system can be exploited if discovered.