This article is based on MOS Note:340009.1 and presents some basic steps to increase the security of your Oracle database servers.
Related articles.
By default Oracle creates a number of schemas, each with a default password. Although many of these users are locked, it is still good practice to switch to non-default passwords in case the are unlocked by mistake. In addition, regular users often switch their passwords to match their username. Both of these situations represent a security risk.
Pete Finnigan has an Oracle Default Password Auditing Tool that checks for default passwords, and users whose passwords match their usernames. This is pretty handy to pick up any loose ends. To use this tool, download and extract the zip file. Run the osp_install.sql script to install the password checker and the ops_exec.sql file to run it.
Oracle 11g includes a new view called DBA_USERS_WITH_DEFPWD
, which displays all users which have a default password set.
SELECT * FROM dba_users_with_defpwd ORDER BY username; USERNAME ------------------------------ APPQOSSYS BI DIP EXFSYS IX MDDATA MDSYS OLAPSYS ORACLE_OCM ORDDATA ORDPLUGINS ORDSYS OUTLN OWBSYS PM SCOTT SI_INFORMTN_SCHEMA SPATIAL_CSW_ADMIN_USR SPATIAL_WFS_ADMIN_USR WMSYS XDB XS$NULL 22 rows selected. SQL>
The Oracle database includes a range of functionality to help secure database users. Unused accounts should be locked, while accounts that are used intermittently should be unlocked as needed.
ALTER USER scott ACCOUNT UNLOCK; -- Use the schema. ALTER USER scott ACCOUNT LOCK;
The vast majority of the time there is no need to access the SYS and SYSTEM accounts, since you should be using a DBA account to do your day-to-day work. As a result, these should be locked and only unlocked when needed. So for example, I might do the following.
CREATE USER tim_hall IDENTIFIED BY MyPassword; GRANT DBA TO tim_hall; ALTER USER sys ACCOUNT LOCK; ALTER USER system ACCOUNT LOCK;
Once this is done, all DBA work would be performed using the TIM_HALL users. If SYS or SYSTEM were needed, they could be unlocked, then locked again.
Notes.
Password aging, expiration and history is managed via profiles, as shown below.
CONN sys/password AS SYSDBA CREATE PROFILE my_profile LIMIT FAILED_LOGIN_ATTEMPTS 3 -- Account locked after 3 failed logins. PASSWORD_LOCK_TIME 5 -- Number of days account is locked for. UNLIMITED required explicit unlock by DBA. PASSWORD_LIFE_TIME 30 -- Password expires after 90 days. PASSWORD_GRACE_TIME 3 -- Grace period for password expiration. PASSWORD_REUSE_TIME 120 -- Number of days until a specific password can be reused. UNLIMITED means never. PASSWORD_REUSE_MAX 10 -- The number of changes required before a password can be reused. UNLIMITED means never. / ALTER USER scott PROFILE my_profile;
The PASSWORD_REUSE_TIME
and PASSWORD_REUSE_MAX
parameters work in conjunction. If either one is set to unlimited and the other set to an integer value, password reuse is prevented.
Notes.
Password complexity is enforced using a verification function. Oracle provide an example password verification function in the "$ORACLE_HOME/rdbms/admin/utlpwdmg.sql" file, but you can code a custom one if you prefer. The function must accept three parameters (username, password and old_password) and return a boolean value, where the value TRUE signifies the password is valid. The simple example below just forces the password to be at least 8 characters long.
CREATE OR REPLACE FUNCTION my_verification_function ( username VARCHAR2, password VARCHAR2, old_password VARCHAR2) RETURN BOOLEAN AS BEGIN IF LENGTH(password) < 8 THEN RETURN FALSE; ELSE RETURN TRUE; END IF; END my_verification_function; /
Once the function is compiled under the SYS schema it can be referenced by the PASSWORD_VERIFY_FUNCTION
parameter of a profile.
ALTER PROFILE my_profile LIMIT PASSWORD_VERIFY_FUNCTION my_verification_function;
The code below assigns the completed profile to a user and tests it.
SQL> ALTER USER scott PROFILE my_profile; User altered. SQL> ALTER USER scott IDENTIFIED BY small; ALTER USER scott IDENTIFIED BY small * ERROR at line 1: ORA-28003: password verification for the specified password failed ORA-28003: password verification for the specified password failed SQL> ALTER USER scott IDENTIFIED BY much_bigger; User altered. SQL>
A more complete example of a password verification function is provided by the "$ORACLE_HOME/rdbms/admin/utlpwdmg.sql" script.
If you have trouble thinking of strong passwords, try using a password generator like RandPass.com. It creates random strong passwords with a phonetic sound, making them easier to remember.
In Oracle 11g the "$ORACLE_HOME/rdbms/admin/utlpwdmg.sql" script has been updated to improve the default password verification function. It also applies the function to the DEFAULT profile, enabling it for all users.
Notes.
From Oracle 11g onward, passwords can be case sensitive. You can read more about how to configure this here.
Prior to Oracle 10g, every user with access to the DBMS_JOB
package had the ability to schedule database jobs. In these versions this does not represent an obvious security risk, but it allows users to schedule untuned and intensive operations that can reduce database performance. For this reason I suggest removing public access to the DBMS_JOB
package, and the DBMS_REFRESH
package, which can also schedule jobs.
REVOKE EXECUTE ON dbms_job FROM PUBLIC; REVOKE EXECUTE ON dbms_refresh FROM PUBLIC;
Oracle 10g Release 1 (10.1.0) introduced a new scheduler, along with the concept of external jobs. This scheduler is secured with two new privileges (CREATE JOB
and CREATE ANY JOB
), neither of which are granted by default. At first this seems like an improvement, but the ability to create a job as any user allows the grantee full access to the SYS user and its privileges. I see no reason to ever grant a user the CREATE ANY JOB
privilege, and I would avoid granting the CREATE JOB
privilege if possible.
External jobs present an equally large threat as they allow access to the full power of the underlying operating system, including OS authentication connections to the database. In Oracle 10g Release 1 there is no distinction between an internal job and an external job as far as privileges are concerned, so even the CREATE JOB
privilege represents a massive security breach. In Oracle 10g Release 2 (10.2.0) this situation is improved by the addition of the CREATE EXTERNAL JOB
privilege, allowing access to internal and external jobs to be granted separately. Even so, access to the scheduler should be guarded very carefully.
As a rule of thumb, you should grant users the smallest number of privileges necessary to do their job.
MOS Note:340009.1 discusses the Oracle Voyager Worm and suggests that removal of excessive privileges may prevent attacks from happening in the first place, or spreading from a compromised system.
REVOKE CREATE DATABASE LINK FROM connect; REVOKE EXECUTE ON utl_tcp FROM public; REVOKE EXECUTE ON utl_smtp FROM public; REVOKE EXECUTE ON utl_http FROM public; REVOKE EXECUTE ON utl_mail FROM public; REVOKE EXECUTE ON utl_inaddr FROM public; REVOKE EXECUTE ON utl_file FROM public; REVOKE EXECUTE ON dbms_java FROm public;
In the same way, granting excessive numbers of roles may be dangerous. Instead create you own roles that contain only necessary privileges.
In versions prior to 10g Release 1, the TNS listener should be password protected using the lsnrctl
utility or the netmgr
GUI. When using the lsnrctl
utility, the change_password
command is used to set the password for the first time, or to change an existing password.
LSNRCTL> change_password Old password: New password: Reenter new password: Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=myserver.mydomain)(PORT=1521))) Password changed for LISTENER The command completed successfully LSNRCTL>
The "Old password:" value should be left blank if the password is being set for the first time. Once the new password is set, the configuration should be saved using the save_config
command.
LSNRCTL> save_config Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=myserver.mydomain)(PORT=1521))) Saved LISTENER configuration parameters. Listener Parameter File /u01/app/oracle/product/10.1.0/db_1/network/admin/listener.ora Old Parameter File /u01/app/oracle/product/10.1.0/db_1/network/admin/listener.bak The command completed successfully LSNRCTL>
Once the password is set, subsequent attempts to perform privileged operations such as save_config
and stop
will fail unless the password is set using the set password
command.
LSNRCTL> set password Password: The command completed successfully LSNRCTL>
The image below shows the same operation being performed by the Oracle Net Manager (netmgr) GUI.
In addition to password protection, MOS Note:340009.1 suggests changing the TNS listener default port from 1521 to a different port. This will certainly help prevent generic attacks where worms are specifically targeting port 1521, but will only cause a minor delay for a targeted hack where open ports are scanned.
The TNS listener port settings are configured by editing the "$ORACLE_HOME/network/admin/listener.ora" file and restarting, or reloading, the listener. In addition, the LDAP entries or local "$ORACLE_HOME/network/admin/tnsnames.ora" file entries of any clients must be modified to reflect the changes.
Client access to the server can be restricted by adding the following entries to the "$ORACLE_HOME/network/admin/sqlnet.ora" file from 11g onward, or in the "$ORACLE_HOME/network/admin/protocol.ora" file for versions prior to 11g.
tcp.validnode_checking = YES tcp.excluded_nodes = {list of IP addresses} tcp.invited_nodes = {list of IP addresses}
This may work OK in a 3-tier architecture where only a small number of applicaton servers connect to the database.
An AFTER LOGON
trigger can be used to lock down access to specific schemas. The trigger below only allows access to USER1 and USER2 when the connection is made from the IP addresses "192.168.0.101" and "192.168.0.102".
CREATE OR REPLACE TRIGGER system.check_ip_addresses AFTER LOGON ON DATABASE BEGIN IF USER IN ('USER1', 'USER2') THEN IF SYS_CONTEXT('USERENV', 'IP_ADDRESS') NOT IN ('192.168.0.101','192.168.0.102') THEN RAISE_APPLICATION_ERROR(-20000, 'Can not log in from this IP address (' || l_ip_address || ')'); END IF; END IF; END; /
You can make this sort of trigger as complex or simple as you like. Just remember the following points:
ON DATABASE
, as making it schema specific would prevent the RAISE_APPLICATION_ERROR
from preventing the logon.07_DICTIONARY_ACCESSIBILITY
initialization parameter to FALSE. The prevents users with ALL
-type system privileges modifying the data dictionary, unless they are a DBA-privileged account.For more information see:
Hope this helps. Regards Tim...
Back to normal view: https://oracle-base.com/articles/misc/basic-security-measures-for-oracle