--Execute as sys

CREATE OR REPLACE
PROCEDURE change_password(p_username VARCHAR2 DEFAULT NULL,
                          p_new_password VARCHAR2 DEFAULT NULL)
IS
  v_sql_stmt VARCHAR2(500);
BEGIN
  v_sql_stmt := 'ALTER USER '||p_username ||' IDENTIFIED BY '
                  || p_new_password;
  EXECUTE IMMEDIATE v_sql_stmt;
END change_password;
/
