The Communication layer used by Oracle databases is referred as Transparent Network Substrate (TNS). TNS name is extremely important component of Oracle database connectivity. It is the unique identifier for Oracle database on the network. TNS password cracking is among the easiest way to attain access and intrude into the system by the hacker. Prior to 10g, TNS listener with blank password is installed by default. In later versions, database administrator assigns TNS name and passwords to specific oracle database while they do Oracle installations and configuration.

TNS password is an ignored security concerns of database administrators whereas it is the most common method to get enter into the Oracle database. Oracle TNS listener without password is a very common vulnerability which exist in an Oracle database. It gives an open invitation to intruders to get control of the most precious assets of an organization. A hacker can rename a TNS listener password through exploiting TNS listener vulnerability and gaining access to the system through remote machine. Hackers can also gain access to TNS listener log files once TNS listener password is exploited. It will easily allow remote user to shutdown the TNS listener.
Once Oracle TNS listener security is compromised then it becomes easy for intruder to get connected with Oracle database.