OWASP Backend Security Project Oracle Hardening

= Overview =

= Description =

Installation security
This section is useful to understand how the installation will introduce vulnerabilities if it is not made “security oriented”.

Options and products
You should use a advanced installation to custom the installation process so that you be able to install only the component required by application will connect to database.

Sample schemas
You should review installed schema, especially the sample schemas provided by Oracle base installation, and remove any schema you do not need.

Example SQL to remove a schema:

SQL> DROP USER  CASCADE;

Initialization parameters
This section cover the Oracle Initialization parameters that are relevant for the security aspects. All the following initialization parameters have to be specified for all Oracle instances.

Example SQL for setting the REMOTE_OS_AUTHENTICATION parameter:

SQL> ALTER SYSTEM SET REMOTE_OS_AUTHENTICATION = FALSE SCOPE=BOTH

Scope:
 * MEMORY: This value change the instance immediately, but the configuration is lost after a restart.
 * SPFILE: This value NOT change the instance immediately, but a restart is necessaty to take effect.
 * BOTH:  This value change the instance immediately as well as the spfile.

Owner account
The Oracle OS installation account, owner of all Oracle application and datafiles, should be used only for the update and maintenance of the Oracle software and will not be used during the standard DBA activities. The individual DBAs will have to use their assigned OS personal accounts, so the auditing process will be able to actions performed with the correct OS account. The Oracle software installation account will not be a member of the administrative group.

Files and directories
All files and directories generated during the installation process of Oracle should be restricted to the Oracle software owner and the DBA user group, especially the file list below:

Other accounts should be denied access except to executables under the “bin” directory although you sholud configure the permission of all files stored in the “bin” directory in order to be owned by the Oracle software installation account.

Patching
You should keep up to date the Oracle Database therefore, periodically, you should check the Oracle Technology Network web site (http://otn.oracle.com/deploy/security/alerts.htm) to keep up on security alerts issued from Oracle Corporation in regard to all installed components.

Sometime, there are public vulnerility about Oracle software without a patch so it is a good idea subscribe to the security mailing lists so that you will be able to catch those new security issues and to find a way to mitigate the risk of the new vulnerability.

Lock and expire unused accounts
A number of default database server user accounts are create during the installation process so, if you do not use the Database Configuration Assistant, you should lock and expire all default database user accounts. Unlock only those accounts that need to be accessed on a regular basis and assign a strong password to each of these unlocked accounts.

Example SQL for reviewing the Oracle Default Accounts with status “OPEN”:

SQL> SELECT  FROM dba_users WHERE account_status <> ’OPEN’ ORDER BY ;

Example SQL for Locking Accounts:

SQL> ALTER USER  ACCOUNT LOCK;

Change default password
The major weakness concerning the password is that some user default account, after the installation, still has a default password associated with it, so you should be review the passwords of all default accounts (SYS, SYSTEM, DBSNMP, OUTLN and so on) and change it if necessary.

Enforce password policy
The password policy should be enforced by password verification function setting password parameter (list below) and providing password complexity feature like minimum length, password not same as the username, the password contains repeating characters, the password differs from the previous password by at least a maximal number of letters.

Example SQL for setting a password verification function to a profile:

SQL> CREATE PROFILE  LIMIT PASSWORD_VERIFICATION_FUCTION 

Example SQL for assigning profile profile to a user:

SQL> CREATE USER  IDENTIFIED BY PROFILE ;

Privileges and Roles
Due to the great number and variety of applications that make use of the database, it’s difficult to define in advance witch kind of privilege have to be grant to a user. In order to make this choice, you should practice the “principle of least privilege”, that is not providing database users, especially PUBLIC, more privileges than necessary.

The user privileges are split in System Privileges and Object Privileges, you can grant privileges to users explicitly:

SQL> GRANT  ON  TO ; SQL> GRANT  TO  [WITH ADMIN OPTION];

Where “WITH ADMIN OPTION” means that the new user can grant the same system privilege to another user.

Also, you can grant privileges to a role (recommended), a group of privileges:

SQL> GRANT  ON  TO ; SQL> GRANT <system_privilege> TO <role_name>;

and then you should grant the role to users:

SQL> GRANT <role_name> TO <user_name>;

Periodically, you should review the privileges (system and object) of the all database user. As an example, you can use the follow SQL script by executing as a user with the right privileges in order to review the system privilege (only) of specific user:

set pagesize 0 set head off set feed off set linesize 240 set trimspool on col ord noprint set echo off accept username prompt' Insert a value for username:' SELECT LPAD(' ', 2*level) || granted_role "USER PRIVS" FROM (   SELECT NULL grantee,  username granted_role    FROM dba_users    WHERE username LIKE UPPER('&&username')    UNION    SELECT grantee, granted_role    FROM dba_role_privs    UNION    SELECT grantee, privilege    FROM dba_sys_privs) START WITH grantee IS NULL CONNECT BY grantee = prior granted_role;

An example of output: Insert a value for username: owasp OWASP CONNECT CREATE SESSION RESOURCE CREATE CLUSTER CREATE INDEXTYPE CREATE OPERATOR CREATE PROCEDURE CREATE SEQUENCE CREATE TABLE CREATE TRIGGER CREATE TYPE UNLIMITED TABLESPACE

Afterward revoke the privileges that is not necessary from user:

SQL> REVOKE <system_privilege> FROM <user_name>; SQL> REVOKE <object_privilege> ON <object_name> FROM <user_name>;

or from role:

SQL> REVOKE <system_privilege> FROM <role_name>; SQL> REVOKE <object_privilege> ON <object_name> FROM <role_name>;

Automated processing database accounts
The major weakness using batch jobs is to manage user names and passwords in fact, typically, it connects to databases by using directly the command sqlplus:

sqlplus -s <user_name>/ @<TNS alias> << EOF <SQL statement> EOF

In this way you can just see the username and password in clear text by using the command to check the process status, such as “ps” command in unix environment. To avoid it you can use a standard CONNECT statement within batch jobs, like this:

sqlplus /nolog << EOF CONNECT <user_name>/ <SQL statement> EOF

In this last case it is suggested to save the crypted password in a well protected configuration file and then decrypting them just before execute the CONNECT statement.

Another (recommended) possibility is to delegate the password management to a guaranteeded third part as Secure External Password Store provided by Oracle Advanced Security component that save the credentials in a secure way.

When the clients are configured to use the secure external password store, batch jobs can connect to a database replacing the login credentials with an alias (database connection string) stored into container (named wallet).

To enable clients to use the external password store the first thing to do is to create an Oracle wallet with the autologin feature (access to wallet contents not require a password ) by using the follow command from OS command prompt:

mkstore -wrl <wallet_location> -create

Then, you should create database connection credentials in the wallet:

mkstore -wrl <wallet_location> -createCredential <db_connect_string> <user_name>

After the wallet is ready, you should force the client to use the information stored in the “secure password store” to authenticate to databases by configuring sqlnet.ora file.

Example of entries to add in sqlnet.ora file:

WALLET_LOCATION = (SOURCE =       (METHOD = FILE)        (METHOD_DATA = (DIRECTORY = <wallet_location>) )       )

SQLNET.WALLET_OVERRIDE = TRUE

The same configuration are possible to do by using Oracle Wallet Manager.

Doing in this way the risk is reduced because passwords are no exposed in the clear considering the applications can connect to a database with the following CONNECT statement syntax:

connect /@<db_connect_string>

where “db_connect_string” is the database connection credential, created before.

Encrypt network logins
The password information in a connection request should be encrypted to protect against network eavesdropping. The value of the follow parameter should be review:

ORA_ENCRYPT_LOGIN (on the client machine) DBLINK_ENCRYPT_LOGIN (on the server machine)

Once these parameters have been set to TRUE, passwords will be encrypted in connection requests. Note that on Oracle version 9.02 and later these parameter are not available, in fact it is encrypt automatically the password information when transmitting over a network, although the setting or changing of passwords is NOT encrypted when across the network.

Protect network communications
You should configure the Oracle Advanced Security component to use Secure Socket Layer (SSL) as to encrypt network traffic between clients and databases to avoid network eavesdropping. Enabling the protection about network communication by following the next step:

...

XML database (XDB) protocol server
The XML Database (XDB) offers access to the Oracle XML DB resources using the standard Internet protocols FTP, listening on TCP port 2100, and HTTP, listening on TCP port 8080. The Oracle XML DB Protocol Server is a specific type of Oracle shared server dispatcher and is specified in the Oracle database initialization parameter file for startup, so if XDB is not used it should be turned off editing the init<SID>.ora or spfile<SID>.ora (replace SID with the name of your SID) file and remove or comment the follow line:

dispatchers="(PROTOCOL=TCP) (SERVICE=<SID>XDB)"

If access via the Internet protocols is required, logging should be enabled by setting the “ftp-log-level” and “http-log-level” parameters to a value of 1 in xdbconfig.xml file.

Password
A listener password should be set at the end of listener configuration process to avoid from unauthorized start, stop, and configure. The password will be stored in encrypted format within the listener.ora file by using the LSNRCTL utility:

LSNRCTL> set current_listener <listener_name> LNSRCTL> set password Password: (type "enter" if it is the first time) The command completed successfully LSNRCTL> change_password Old password: (type "enter") New password: <new_password> Reenter new password: <new_password> […]  The command completed successfully LSNRCTL> save_config (important to save the configuration) […]  Saved LISTENER configuration parameters. Listener Parameter File […] Old Parameter File […] The command completed successfully LSNRCTL> exit

Admin restrictions
The remote administration of the Oracle listener should be prevent by setting to TRUE the ADMIN_RESTRICTIONS parameter in the listener.ora file:

ADMIN_RESTRICTIONS_<listener_name> = TRUE

Network address restriction
The network address restrictions should be enforced by the Oracle listener to further protect your database from unauthorized remote access. Network address restriction is required when the PLSQL EXTPROC is in use to protect against unauthenticated access to the database. To enable network address restriction, edit the SQLNET.ORA to add the follow line:

TCP.VALIDNODE_CHECKING = YES

Then, to defines TCP/IP addresses that are allowed to connect to database add the follow line:

TCP.INVITED_NODES = <list of IP addresses>

At the end, to defines TCP/IP addresses that are refused connections to the database set the follow parameter

TCP.EXCLUDED_NODES = <list of IP addresses>

External procedures
The EXTPROC functionality used by PL/SQL component to make calls to the operating system and to load necessary library to execute external procedure, but if the Oracle Database server is not properly patched it even could allows unauthorized administrative access to the server machine through the Oracle Listener. If the EXTPROC functionality is not required, you should disable it by editing the tnsname.ora and listener.ora files and removing the entries regarding this functionality.

Example of entries to remove in tnsname.ora file:

[…]    EXTPROC_CONNECTION_DATA = (DESCRIPTION =    (ADDRESS_LIST = (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC)) )     (CONNECT_DATA = (SID = PLSExtProc) (PRESENTATION = RO) )    )  […]

Example of entries to remove in listener.ora file:

[…]     (ADDRESS_LIST =         (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))       ) […]

[…]    (SID_DESC =       (SID_NAME = PLSExtProc)       (ORACLE_HOME = […])      ) […]

After that you should restart the Oracle Net listener process.

Then you should check if the configuration take effect by using the operation status in LSNRCTL command. You should review the configuration if the last command display the follow lines:

Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC))) […]  Services Summary...   Service "PLSExtProc" has 1 instance(s). Instance "PLSExtProc", status UNKNOWN, has 1 handler(s) for this service... […]

Otherwise, the configuration is correct!

If, instead, the EXTPROC functionality is required in your environment, you should configure a Oracle Net Listener for PL/SQL EXTPROC with an IPC (recommended) or TCP protocol address. It is a good idea enforce the network address restrictions when you use the TCP protocol address.

Inbound connection timeout
The amount of time the listener waits for a network client to complete the connection request should be manage to prevent a denial of service attack. The name of parameter to set to configure inbound connection timeout and the name of the file of configuration, depends on Oracle version.

Audit
= References =

[1] The Oracle Hacker's Handbook: Hacking and Defending Oracle by David Litchfield

[2] The Database Hacker's Handbook: Defending Database Servers by David Litchfield

[3] Database Security Technical Implementation Guide by DISA for the DOD

[4] Oracle Database Security Guide by Oracle Corporation

[5] Oracle Database Security Checklist by Oracle Corporation