2.1.2 Ensure 'extproc' Is Not Present in 'listener.ora'
Information
extproc should be removed from the listener.ora to mitigate the risk that OS libraries can be invoked by the Oracle instance. Rationale: extproc allows the database to run procedures from OS libraries. These library calls can, in turn, run any OS command.
Solution
To remediate this recommendation: Remove extproc from the listener.ora file. References: http://docs.oracle.com/database/121/DBSEG/app_devs.htm#DBSEG656