Information
The permissions of the binaries for sqlplus on the server must be restricted to the owner of the Oracle software and the dba group.
Level 1, Scorable
NOTE: Change 'ORACLE_HOME' to the directory where your Oracle installation is located.
ref: https://benchmarks.cisecurity.org/tools2/oracle/CIS_Oracle_11g_Benchmark_v1.0.1.pdf, pg 29.