When application developers design applications, one of the first steps is to create an effective security policy. The security policy should encompass areas such as password management, ways to secure external procedures and application privileges, management of application and database roles, and how to protect schema objects.
Topics:
Creating an application security policy is the first step to create a secure database application. An application security policy is a list of application security requirements and rules that regulate user access to database objects.
You should draft security policies for each database application. For example, each database application should have one or more database roles that provide different levels of security when executing the application. You then can grant the database roles to other roles or directly to specific users.
Applications that can potentially allow unrestricted SQL statement processing (through tools such as SQL*Plus or SQL Developer) also need security policies that prevent malicious access to confidential or important schema objects. In particular, you must ensure that your applications handle passwords in a secure manner.
The following sections describe aspects of application security and the Oracle Database features that you can use to plan and develop secure database applications.
Two main questions to consider when you formulate and implement application security concern the distinction between application and database users, and whether security is better enforced in the application or in the database.
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Where possible, you should build applications in which application users are database users. In this way, you can leverage the intrinsic security mechanisms of the database.
For many commercial packaged applications, application users are not database users. For these applications, multiple users authenticate themselves to the application, and the application then connects to the database as a single, highly-privileged user. This is called the One Big Application User model.
Applications built in this way generally cannot use many of the intrinsic security features of the database, because the identity of the user is not known to the database.
Table 8-1 describes how the One Big Application User model affects various Oracle Database security features:
Table 8-1 Features Affected by the One Big Application User Model
Applications, whose users are also database users, can either build security into the application, or rely on intrinsic database security mechanisms such as granular privileges, virtual private databases (fine-grained access control with application context), roles, stored procedures, and auditing (including fine-grained auditing).
Oracle recommends that applications use the security enforcement mechanisms of the database as much as possible.
When security is enforced in the database itself, rather than in the application, it cannot be bypassed. The main shortcoming of application-based security is that security is bypassed if the user bypasses the application to access data. For example, a user who has SQL*Plus access to the database can execute queries without going through the Human Resources application. The user, therefore, bypasses all of the security measures in the application.
Applications that use the One Big Application User model must build security enforcement into the application rather than use database security mechanisms. Because it is the application, and not the database, that recognizes users; the application itself must enforce security measures for each user.
This approach means that each application that accesses data must reimplement security. Security becomes expensive, because organizations must implement the same security policies in multiple applications, and each new application requires an expensive reimplementation.
Oracle Database provides strategies for securely invoking password-protected services from a batch job, script, installation file, or application. In addition to password protection, most of these strategies can be applied to other sensitive data, such as cryptographic keys.
Topics:
See Also:
Appendix A, "Keeping Your Oracle Database Secure," for general guidelines on securing an Oracle database
Guidelines for securing passwords in applications cover platform-specific security threats, password input, password formats and behavior, and ways to handle passwords in SQL*Plus and SQL scripts.
Topics:
Guidelines for Designing Applications to Handle Password Input
Guidelines for Handling Passwords in SQL*Plus and SQL Scripts
You should be aware of potential security threats, which may not be obvious.
On UNIX and Linux platforms, command parameters are available for viewing by all operating system users on the same host computer. As a result, passwords entered on the command line could be exposed to other users. However, do not assume that non-UNIX and Linux platforms are safe from this threat.
On some UNIX platforms, such as HP Tru64 and IBM AIX, environment variables for all processes are available for viewing by all operating system users. However, do not assume that non-UNIX and Linux platforms are safe from this threat.
On Microsoft Windows, the command recall feature (the Up arrow) remembers user input across command invocations. For example, if you use the CONNECT SYSTEM/
password
notation in SQL*Plus, exit, and then press the Up arrow to repeat the CONNECT
command, the command recall feature reveals the connect string and displays the password. In addition, do not assume that non-Microsoft Windows platforms are safe from this threat.
Oracle Database provides guidelines for designing applications to handle password input.
Design applications to interactively prompt for passwords. For command-line utilities, do not force users to expose passwords at a command prompt.
Check the APIs for the programming language you use to design applications for the best way to handle passwords from users. For an example of Java code that handles this functionality, see "Example of Reading Passwords in Java".
Protect your database against SQL injection attacks. A SQL injection attack occurs when SQL statements are appended or altered in a manner not intended by the PL/SQL application. For example, an intruder can bypass password authentication by setting a WHERE
clause to TRUE
.
To address the problem of SQL injection attacks, use bind variable arguments or create validation checks. If you cannot use bind variables, then consider using the DBMS_ASSERT
PL/SQL package to validate the properties of input values. Oracle Database PL/SQL Packages and Types Reference describes the DBMS_ASSERT
package in detail. You also should review any grants to roles such as PUBLIC
.
See Oracle Database PL/SQL Language Reference for more information about preventing SQL injection.
If possible, design your applications to defer authentication. For example:
Use certificates for logins.
Authenticate users by using facilities provided by the operating system. For example, applications on Microsoft Windows can use domain authentication.
Mask or encrypt passwords. If you must store passwords, then mask or encrypt them. For example, you can mask passwords in log files and encrypt passwords in recovery files.
Authenticate each connection. For example, if schema A exists in database 1, then do not assume that schema A in database 2 is the same user. Similarly, the local operating system user psmith
is not necessarily the same person as remote user psmith
.
Do not store clear text passwords in files or repositories. Storing passwords in files increases the risk of an intruder accessing them.
Use a single master password. For example:
You can grant a single database user proxy authentication to act as other database users. In this case, only a single database password is needed. See "Proxy User Accounts and the Authorization of Users to Connect Through Them" for more information.
You can create a password wallet, which can be opened by the master password. The wallet then contains the other passwords. See Oracle Database Enterprise User Security Administrator's Guide for more information about Wallet Manager.
Oracle Database provides guidelines for configuring password formats and behavior.
Limit the lifetime for passwords. You can set a password lifetime, after which the password expires and must be changed before the user can log in to the account. See "About Controlling Password Aging and Expiration" for parameters you can use to control the lifetime of a password.
Limit the ability of users to reuse old passwords. See "Control of the User Ability to Reuse Previous Passwords" for more information.
Force users to create strong, secure passwords. See "Guidelines for Securing Passwords" for advice on creating strong passwords. "About Password Complexity Verification" explains how you can customize password requirements.
Enable case sensitivity in passwords. See "Enabling Password Case Sensitivity" for more information.
Oracle Database provides guidelines for handling passwords in SQL*Plus and SQL scripts.
Do not invoke SQL*Plus with a password on the command line, either in programs or scripts. If a password is required but omitted, SQL*Plus prompts the user for it and then automatically disables the echo feature so that the password is not displayed.
The following examples are secure because passwords are not exposed on the command line. Oracle Database also automatically encrypts these passwords over the network.
$ sqlplus system Enter password: password SQL> CONNECT SYSTEM Enter password: password
The following example exposes the password to other operating system users:
sqlplus system/password
The next example poses two security risks. First, it exposes the password to other users who may be watching over your shoulder. Second, on some platforms, such as Microsoft Windows, it makes the password vulnerable to a command line recall attack.
$ sqlplus /nolog
SQL> CONNECT SYSTEM/password
For SQL scripts that require passwords or secret keys, for example, to create an account or to log in as an account, do not use positional parameters, such as substitution variables &1, &2, and so on. Instead, design the script to prompt the user for the value. You should also disable the echo feature, which displays output from a script or if you are using spool mode. To disable the echo feature, use the following setting:
SET ECHO OFF
A good practice is to ensure that the script makes the purpose of the value clear. For example, it should be clear whether or not the value will establish a new value, such as an account or a certificate, or if the value will authenticate, such as logging in to an existing account.
The following example is secure because it prevents users from invoking the script in a manner that poses security risks: It does not echo the password; it does not record the password in a spool file.
1 2 3 4 |
SET VERIFY OFF ACCEPT user CHAR PROMPT ’Enter user to connect to: ’ ACCEPT password CHAR PROMPT ’Enter the password for that user: ' HIDE CONNECT &user/&password |
In this example:
Line 1: Prevents the password from being displayed. (SET VERIFY
lists each line of the script before and after substitution.) Combining the SET VERIFY OFF
command with the HIDE
command (in Line 3) is a useful technique for hiding passwords and other sensitive input data.
Line 3: Includes the HIDE
option for the ACCEPT password
prompt, which prevents the input password from being echoed.
The next example, which uses positional parameters, poses security risks because a user may invoke the script by passing the password on the command line. If the user does not enter a password and instead is prompted, the danger lies in that whatever the user types is echoed to the screen and to a spool file if spooling is enabled.
CONNECT &1/&2
Control the log in times for batch scripts. For batch scripts that require passwords, configure the account so that the script can only log in during the time in which it is supposed to run. For example, suppose you have a batch script that runs for an hour each evening starting at 8 p.m. Set the account so that the script can only log in during this time. If an intruder manages to gain access, then he or she has less of a chance of exploiting any compromised accounts.
Be careful when using DML or DDL SQL statements that prompt for passwords. In this case, sensitive information is passed in clear text over the network. You can remedy this problem by using Oracle strong authentication.
The following example of altering a password is secure because the password is not exposed:
password psmith Changing password for psmith New password: password Retype new password: password
This example poses a security risk because the password is exposed both at the command line and on the network:
ALTER USER psmith IDENTIFIED BY password
You can store password credentials for connecting to a database by using a client-side Oracle wallet.
An Oracle wallet is a secure software container that stores the authentication and signing credentials needed for a user to log in.
See Also:
"Managing the Secure External Password Store for Password Credentials" for more information about the secure external password store
Oracle Database Enterprise User Security Administrator's Guide for information about using Oracle Wallet Manager to configure Oracle wallets
You can create a password file for users who need to connect to an application using the SYSDBA
or SYSOPER
administrative privileges over a network.
To create the password file, use the ORAPWD
utility.
See Also:
Oracle Database Administrator's Guide for more information about creating and maintaining a password fileExample 8-1 demonstrates how to create a Java package that can be used to read passwords.
Example 8-1 Java Code for Reading Passwords
// Change the following line to a name for your version of this package package passwords.sysman.emSDK.util.signing; import java.io.IOException; import java.io.PrintStream; import java.io.PushbackInputStream; import java.util.Arrays; /** * The static readPassword method in this class issues a password prompt * on the console output and returns the char array password * entered by the user on the console input. */ public final class ReadPassword { //---------------------------------- /** * Test driver for readPassword method. * @param args the command line args */ public static void main(String[] args) { char[] pass = ReadPassword.readPassword("Enter password: "); System.out.println("The password just entered is \"" + new String(pass) + "\""); System.out.println("The password length is " + pass.length); } * Issues a password prompt on the console output and returns * the char array password entered by the user on the console input. * The password is not displayed on the console (chars are not echoed). * As soon as the returned char array is not needed, * it should be erased for security reasons (Arrays.fill(charArr, ' ')); * A password should never be stored as a java String. * * Note that Java 6 has a Console class with a readPassword method, * but there is no equivalent in Java 5 or Java 1.4. * The readPassword method here is based on Sun's suggestions at * http://java.sun.com/developer/technicalArticles/Security/pwordmask. * * @param prompt the password prompt to issue * @return new char array containing the password * @throws RuntimeException if some error occurs */ public static final char[] readPassword(String prompt) throws RuntimeException { try { StreamMasker masker = new StreamMasker(System.out, prompt); Thread threadMasking = new Thread(masker); int firstByte = -1; PushbackInputStream inStream = null; try { threadMasking.start(); inStream = new PushbackInputStream(System.in); firstByte = inStream.read(); } finally { masker.stopMasking(); } try { threadMasking.join(); } catch (InterruptedException e) { throw new RuntimeException("Interrupt occurred when reading password"); } if (firstByte == -1) { throw new RuntimeException("Console input ended unexpectedly"); } if (System.out.checkError()) { throw new RuntimeException("Console password prompt output error"); } inStream.unread(firstByte); return readLineSecure(inStream); } catch (IOException e) { throw new RuntimeException("I/O error occurred when reading password"); } } //---------------------------------- /** * Reads one line from an input stream into a char array in a secure way * suitable for reading a password. * The char array will never contain a '\n' or '\r'. * * @param inStream the pushback input stream * @return line as a char array, not including end-of-line-chars; * never null, but may be zero length array * @throws RuntimeException if some error occurs */ private static final char[] readLineSecure(PushbackInputStream inStream) throws RuntimeException { if (inStream == null) { throw new RuntimeException("readLineSecure inStream is null"); } try { char[] buffer = null; try { buffer = new char[128]; int offset = 0; // EOL is '\n' (unix), '\r\n' (windows), '\r' (mac) loop: while (true) { int c = inStream.read(); switch (c) { case -1: case '\n': break loop; case '\r': int c2 = inStream.read(); if ((c2 != '\n') && (c2 != -1)) inStream.unread(c2); break loop; default: buffer = checkBuffer(buffer, offset); buffer[offset++] = (char) c; break; } } char[] result = new char[offset]; System.arraycopy(buffer, 0, result, 0, offset); return result; } finally { if (buffer != null) Arrays.fill(buffer, ' '); } } catch (IOException e) { throw new RuntimeException("I/O error occurred when reading password"); } } //---------------------------------- /** * This is a helper method for readLineSecure. * * @param buffer the current char buffer * @param offset the current position in the buffer * @return the current buffer if it is not yet full; * otherwise return a larger buffer initialized with a copy * of the current buffer and then erase the current buffer * @throws RuntimeException if some error occurs */ private static final char[] checkBuffer(char[] buffer, int offset) throws RuntimeException { if (buffer == null) throw new RuntimeException("checkBuffer buffer is null"); if (offset < 0) throw new RuntimeException("checkBuffer offset is negative"); if (offset < buffer.length) return buffer; else { try { char[] bufferNew = new char[offset + 128]; System.arraycopy(buffer, 0, bufferNew, 0, buffer.length); return bufferNew; } finally { Arrays.fill(buffer, ' '); } } } //---------------------------------- /** * This private class prints a one line prompt * and erases reply chars echoed to the console. */ private static final class StreamMasker extends Thread { private static final String BLANKS = StreamMasker.repeatChars(' ', 10); private String m_promptOverwrite; private String m_setCursorToStart; private PrintStream m_out; private volatile boolean m_doMasking; //---------------------------------- /** * Constructor. * @throws RuntimeException if some error occurs */ public StreamMasker(PrintStream outPrint, String prompt) throws RuntimeException { if (outPrint == null) throw new RuntimeException("StreamMasker outPrint is null"); if (prompt == null) throw new RuntimeException("StreamMasker prompt is null"); if (prompt.indexOf('\r') != -1) throw new RuntimeException("StreamMasker prompt contains a CR"); if (prompt.indexOf('\n') != -1) throw new RuntimeException("StreamMasker prompt contains a NL"); m_out = outPrint; m_setCursorToStart = StreamMasker.repeatChars('\010', prompt.length() + BLANKS.length()); m_promptOverwrite = m_setCursorToStart + prompt + BLANKS + m_setCursorToStart + prompt; } //---------------------------------- /** * Begin masking until asked to stop. * @throws RuntimeException if some error occurs */ public void run() throws RuntimeException { int priorityOriginal = Thread.currentThread().getPriority(); Thread.currentThread().setPriority(Thread.MAX_PRIORITY); try { m_doMasking = true; while (m_doMasking) { m_out.print(m_promptOverwrite); if (m_out.checkError()) throw new RuntimeException("Console output error writing prompt"); try { Thread.currentThread().sleep(1); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); return; } } m_out.print(m_setCursorToStart); } finally { Thread.currentThread().setPriority(priorityOriginal); } } //---------------------------------- /** * Instructs the thread to stop masking. */ public void stopMasking() { m_doMasking = false; } //---------------------------------- /** * Returns a repeated char string. * * @param c the char to repeat * @param length the number of times to repeat the char * @throws RuntimeException if some error occurs */ private static String repeatChars(char c, int length) throws RuntimeException { if (length < 0) throw new RuntimeException("repeatChars length is negative"); StringBuffer sb = new StringBuffer(length); for (int i = 0; i < length; i++) sb.append(c); return sb.toString(); } } }
An external procedure is a procedure that is stored in a .dll
or an .so
file, separately from the database. To secure an external procedure, you can authenticate it through a credential.
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For safety reasons, Oracle external procedures run in a process that is physically separate from the database.
In most cases, you configure this process to execute as a user other than the Oracle software account. When your application invokes this external procedure—such as when a library of .dll
or .so
files must be accessed—then Oracle Database creates an operating system process called extproc
. By default, the extproc
process communicates directly through your server process. In other words, if you do not use a credential, then Oracle Database creates an extproc
process for you in the default Oracle Database server configuration, and runs extproc
as the oracle
software account. Alternatively, it can communicate through the Oracle Database listener.
For better security, you can configure the extproc
process to be authenticated through a credential. The general process is as follows:
You create a credential.
The credential is in an encrypted container. Both public and private synonyms can refer to this credential. "Configuring Authentication for External Procedures" describes how to create this credential and configure your database to use it.
You make your initial connection to the database, which you are running in either a dedicated server or a shared server process.
Your application makes a call to an external procedure.
If this is the first call, then Oracle Database creates an extproc
process. Note that if you want to use a credential for extproc
, then you cannot use the Oracle listener to spawn the extproc
process.
The extproc
process impersonates (that is, it runs on behalf of your supplied credential), loads the requisite .dll
, .so
, .sl
, or .a
file, and then sends your data between SQL and C.
Table 8-2 describes the expected behaviors of an extproc
process based on possible authentication and impersonation scenarios.
Table 8-2 Expected Behaviors for extproc Process Authentication and Impersonation Settings
ENFORCE_CREDENTIAL Environment Variable Setting | PL/SQL Library with Credential? | GLOBAL_EXTPROC_CREDENTIAL Credential ExistenceFoot 1 | Expected Behavior |
---|---|---|---|
|
No |
No |
Uses the pre-Release 12c authentication, which authenticates by operating system privilege of the owners of the Oracle listener or Oracle server process. |
|
No |
Yes |
Authenticates and impersonates with the Oracle instance-wide supplied |
|
Yes |
No |
Authenticates and impersonates with the credential defined in the PL/SQL library |
|
Yes |
Yes |
Authenticates and impersonates (Foot 3 ) |
|
No |
No |
Returns error |
|
No |
Yes |
Authenticates and impersonates with the Oracle system-wide supplied |
|
Yes |
No |
Authenticates and impersonates with the credential defined in the PL/SQL library |
|
Yes |
Yes |
Authenticates and impersonates (footnote 2) |
Footnote 1 GLOBAL_EXTPROC_CREDENTIAL
is a reserved credential name for the default credential if the credential is not explicitly specified and the ENFORCE_CREDENTIAL
environment variable is set to TRUE
. Therefore, Oracle strongly recommends that you create a credential by the that name if ENFORCE_CREDENTIAL
is set to TRUE
.
Footnote 2 If only the GLOBAL_EXTPROC_CREDENTIAL
credential is in use, then the EXECUTE
privilege on this global credential is automatically granted to all users implicitly.
Footnote 3 If both the PL/SQL library and the GLOBAL_EXTPROC_CREDENTIAL
settings have credentials defined, then the credential of the PL/SQL library takes precedence.
To configure a credential for extproc
processes, you can use the DBMS_CREDENTIAL
PL/SQL package.
Log in to SQL*Plus as a user who has been granted the CREATE CREDENTIAL
or CREATE ANY CREDENTIAL
privilege.
sqlplus psmith
Enter password: password
Connected.
In a multitenant environment, you must connect to the appropriate pluggable database (PDB). For example:
sqlplus psmith@hpdb
Enter password: password
Connected.
In addition, ensure that you also have the CREATE LIBRARY
or CREATE ANY LIBRARY
privilege, and the EXECUTE
object privilege on the library that contains the external calls.
Using the DBMS_CREDENTIAL
PL/SQL package, create a new credential.
For example:
BEGIN
DBMS_CREDENTIAL.CREATE_CREDENTIAL (
credential_name => 'smith_credential',
user_name => 'tjones',
password => 'password')
END;
/
In this example:
credential_name
: Enter the name of the credential. Optionally, prefix it with the name of a schema (for example, psmith.smith_credential
). If the ENFORCE_CREDENTIAL
environment variable is set to TRUE
, then you should create a credential with credential_name GLOBAL_EXTPROC_CREDENTIAL
.
user_name
: Enter a valid operating system user name to be to used to run as the user.
password
: Enter the password for the user_name
user.
Associate the credential with a PL/SQL library.
For example:
CREATE OR REPLACE LIBRARY ps_lib AS 'smith_lib.so' IN DLL_LOC CREDENTIAL smith_credential;
In this example, DLL_LOC
is a directory object that points to the $ORACLE_HOME/bin
directory. Oracle does not recommend using absolute paths to the DLL.
When the PL/SQL library is loaded by an external procedure call through the extproc
process, extproc
now can authenticate and impersonate on behalf of the defined smith_credential
credential.
Register the external procedure by creating a PL/SQL procedure or function that tells PL/SQL how to call the external procedure and what arguments to pass to it.
For example, to create a function that registers an external procedure that was written in C, only use the AS LANGUAGE C
, LIBRARY
, and NAME
clauses of the CREATE FUNCTION
statement, as follows:
CREATE OR REPLACE FUNCTION getInt (x VARCHAR2, y BINARY_INTEGER) RETURN BINARY_INTEGER AS LANGUAGE C LIBRARY ps_lib NAME "get_int_vals" PARAMETERS (x STRING, y int);
See Also:
Oracle Database PL/SQL Packages and Types Reference, for information about the DBMS_CREDENTIAL
package
Oracle Call Interface Programmer's Guide for information about the extproc
agent
Oracle Database Net Services Administrator's Guide for detailed information about the extproc.ora
file
For maximum security, set the ENFORCE_CREDENTIAL
environment variable to TRUE
.
However, if you must accommodate backward compatibility, then set ENFORCE_CREDENTIAL
to FALSE
. FALSE
enables the extproc
process to authenticate, impersonate, and perform user-defined callout functions on behalf of the supplied credential when either of the following occurs:
The credential is defined with a PL/SQL library.
The credential is not defined but the GLOBAL_EXTPROC_CREDENTIAL
credential exists.
If neither of these credential definitions is in place, then setting the ENFORCE_CREDENTIAL
parameter to FALSE
sets the extproc
process to be authenticated by the operating system privilege of the owners of the Oracle listener or Oracle server process.
For legacy applications that run on top of extproc
processes, ideally you should change the legacy application code to associate all alias libraries with credentials. If you cannot do this, then Oracle Database uses the GLOBAL_EXTPROC_CREDENTIAL
credential to determine how authentication will be handled. If the GLOBAL_EXTPROC_CREDENTIAL
credential is not defined, then the extproc
process is authenticated by the operating system privilege of the owners of the Oracle listener or Oracle server process.
Most database applications involve different privileges on different schema objects.
Keeping track of the privileges that are required for each application can be complex. In addition, authorizing users to run an application can involve many GRANT
operations.
To simplify application privilege management, you can create a role for each application and grant that role all the privileges a user must run the application. In fact, an application can have several roles, each granted a specific subset of privileges that allow greater or lesser capabilities while running the application.
For example, suppose every administrative assistant uses the Vacation application to record the vacation taken by members of the department. To best manage this application, you should:
Create a VACATION
role.
Grant all privileges required by the Vacation application to the VACATION
role.
Grant the VACATION
role to all administrative assistants. Better yet, create a role that defines the privileges the administrative assistants have, and then grant the VACATION
role to that role.
Grouping application privileges in a role aids privilege management. Consider the following administrative options:
You can grant the role, rather than many individual privileges, to those users who run the application. Then, as employees change jobs, you need to grant or revoke only one role, rather than many privileges.
You can change the privileges associated with an application by modifying only the privileges granted to the role, rather than the privileges held by all users of the application.
You can determine the privileges that are necessary to run a particular application by querying the ROLE_TAB_PRIVS
and ROLE_SYS_PRIVS
data dictionary views.
You can determine which users have privileges on which applications by querying the DBA_ROLE_PRIVS
data dictionary view.
See Also:
Chapter 4, "Configuring Privilege and Role Authorization," for a complete discussion of creating, enabling, and disabling roles, and granting and revoking privileges
"User Privilege and Role Data Dictionary Views" for more information about the security uses of the ROLE_TAB_PRIVS
, ROLE_SYS_PRIVS
, and DBA_ROLE_PRIVS
data dictionary views
As explained in "Securing Role Privileges by Using Secure Application Roles", a secure application role is a role that is only enabled through its associated PL/SQL package or procedure. This package defines the policy needed to control access to an application.
Topics:
See Also:
Oracle Database 2 Day + Security Guide for a tutorial on creating a secure application roleYou create a secure application role by using the SQL statement CREATE
ROLE
with the IDENTIFIED USING
clause. You must have the CREATE
ROLE
system privilege to execute this statement.
For example, to create a secure application role called hr_admin
that is associated with the sec_mgr.hr_admin
package:
Create the security application role as follows:
CREATE ROLE hr_admin IDENTIFIED USING sec_mgr.hr_admin_role_check;
This statement indicates the following:
The role hr_admin
to be created is a secure application role.
The role can only be enabled by modules defined inside the PL/SQL procedure sec_mgr
.hr_admin_role_check
. At this stage, this procedure does not need to exist; "Step 2: Create a PL/SQL Package to Define the Access Policy for the Application" explains how to create the package or procedure.
Grant the security application role the privileges you would normally associate with this role.
For example, to grant the hr_admin
role SELECT
, INSERT
, UPDATE
, and DELETE
privileges on the HR.EMPLOYEES
table, you enter the following statement:
GRANT SELECT, INSERT, UPDATE, DELETE ON HR.EMPLOYEES TO hr_admin;
Do not grant the role directly to the user. The PL/SQL procedure or package does that for you, assuming the user passes its security policies.
You can create a PL/SQL package that defines the access policy for your application.
Topics:
About Creating a PL/SQL Package to Define the Access Policy for an Application
Creating a PL/SQL Package to Define the Access Policy for an Application
To enable or disable the secure application role, you create the security policies of the role within a PL/SQL package. You also can create an individual procedure to do this, but a package lets you group a set of procedures together. This lets you group a set of policies that, used together, present a solid security strategy to protect your applications. For users (or potential intruders) who fail the security policies, you can add auditing checks to the package to record the failure. Typically, you create this package in the schema of the security administrator.
The package or procedure must accomplish the following:
It must use invoker's rights to enable the role.To create the package using invoker's rights, you must set the AUTHID
property to CURRENT_USER
. You cannot create the package by using definer's rights.
For more information about invoker's rights and definer's rights, see Oracle Database PL/SQL Language Reference.
It must include one or more security checks to validate the user. One way to validate users is to use the SYS_CONTEXT
SQL function. See Oracle Database SQL Language Reference for more information about SYS_CONTEXT
. To find session information for a user, you can use SYS_CONTEXT
with an application context. See Chapter 9, "Using Application Contexts to Retrieve User Information," for details.
It must issue a SET ROLE SQL statement or DBMS_SESSION.SET_ROLE procedure when the user passes the security checks. Because you create the package using invoker's rights, you must set the role by issuing the SET ROLE
SQL statement or the DBMS_SESSION.SET_ROLE
procedure. (However, you cannot use the SET ROLE ALL
statement for this type of role enablement.) The PL/SQL embedded SQL syntax does not support the SET ROLE
statement, but you can invoke SET ROLE
by using dynamic SQL (for example, with EXECUTE IMMEDIATE
).
For more information about EXECUTE IMMEDIATE
, see Oracle Database PL/SQL Language Reference.
Because of the way that you must create this package or procedure, you cannot use a logon trigger to enable or disable a secure application role. Instead, invoke the package directly from the application when the user logs in, before the user must use the privileges granted by the secure application role.
For example, suppose you wanted to restrict anyone using the hr_admin
role to employees who are on site (that is, using certain terminals) and between the hours of 8 a.m. and 5 p.m. As the system or security administrator, you can create a procedure that defines the access policy for the application. (You can copy and paste this text by positioning the cursor at the start of CREATE OR REPLACE
in the first line.)
Create the procedure as follows:
1 2 3 4 5 6 7 8 9 10 11 12 13 |
CREATE OR REPLACE PROCEDURE hr_admin_role_check AUTHID CURRENT_USER AS BEGIN IF (SYS_CONTEXT ('userenv','ip_address') BETWEEN '192.0.2.10' and '192.0.2.20' AND TO_CHAR (SYSDATE, 'HH24') BETWEEN 8 AND 17) THEN EXECUTE IMMEDIATE 'SET ROLE hr_admin'; END IF; END; / |
In this example:
Line 2: Sets the AUTHID
property to CURRENT_USER
so that invoker's rights can be used.
Line 5: Validates the user by using the SYS_CONTEXT
SQL function to retrieve the user session information.
Lines 6–8: Create a test to grant or deny access. The test restricts access to users who are on site (that is, using certain terminals) and working between the hours of 8:00 a.m. and 5:00 p.m. If the user passes this check, the hr_admin
role is granted.
Lines 9–10: Assuming the user passes the test, grants the role to the user by issuing the SET ROLE
statement using the EXECUTE IMMEDIATE
command.
Grant EXECUTE
permissions for the hr_admin_role_check
procedure to any user who was assigned it.
For example:
GRANT EXECUTE ON hr_admin_role_check TO psmith;
To test the secure application role, log in to SQL*Plus as the user, try to enable the role, and then try to perform an action that requires the privileges the role grants.
For example:
CONNECT PSMITH@hrpdb Enter password: password EXECUTE sec_admin.hr_admin_role_check; -- Actions requiring privileges granted by the role
Ensure that users have only the privileges associated with the current database role.
Topics:
Why Users Should Only Have the Privileges of the Current Database Role
Use of the SET ROLE Statement to Automatically Enable or Disable Roles
A single user can use many applications and associated roles. However, you should ensure that the user has only the privileges associated with the current database role.
Consider the following scenario:
The ORDER
role (for an application called Order) contains the UPDATE
privilege for the INVENTORY
table.
The INVENTORY
role (for an application called Inventory) contains the SELECT
privilege for the INVENTORY
table.
Several order entry clerks were granted both the ORDER
and INVENTORY
roles.
In this scenario, an order entry clerk who was granted both roles can use the privileges of the ORDER
role when running the INVENTORY
application to update the INVENTORY
table. The problem is that updating the INVENTORY
table is not an authorized action for the INVENTORY
application. It is an authorized action for the ORDER
application. To avoid this problem, use the SET
ROLE
statement as explained in the following section.
You can use a SET
ROLE
statement at the beginning of each application to automatically enable its associated role and to disable all others. This way, each application dynamically enables particular privileges for a user only when required.
The SET
ROLE
statement simplifies privilege management. You control what information users can access and when they can access it. The SET
ROLE
statement also keeps users operating in a well-defined privilege domain. If a user obtains privileges only from roles, then the user cannot combine these privileges to perform unauthorized operations.
See Also:
"When Do Grants and Revokes Take Effect?" for information about enabling and disabling roles
A schema is a security domain that can contain database objects. The privileges granted to each user or role control access to these database objects.
Topics:
You can think of most schemas as user names: the accounts that enable users to connect to a database and access the database objects. However, a unique schema does not allow connections to the database, but is used to contain a related set of objects. Schemas of this sort are created as typical users, and yet are not granted the CREATE
SESSION
system privilege (either explicitly or through a role). However, you must temporarily grant the CREATE
SESSION
and RESOURCE
privilege to a unique schema if you want to use the CREATE
SCHEMA
statement to create multiple tables and views in a single transaction.
For example, a given schema might own the schema objects for a specific application. If application users have the privileges to do so, then they can connect to the database using typical database user names and use the application and the corresponding objects. However, no user can connect to the database using the schema set up for the application. This configuration prevents access to the associated objects through the schema, and provides another layer of protection for schema objects. In this case, the application could issue an ALTER SESSION SET CURRENT_SCHEMA
statement to connect the user to the correct application schema.
For many applications, users do not need their own accounts or schemas in a database. These users only need to access an application schema. For example, users John, Firuzeh, and Jane are all users of the Payroll application, and they need access to the payroll
schema on the finance
database. None of them need to create their own objects in the database. They need to only access the payroll
objects. To address this issue, Oracle Database provides the enterprise users, which are schema-independent users.
Enterprise users, users managed in a directory service, do not need to be created as database users because they use a shared database schema. To reduce administration costs, you can create an enterprise user once in the directory, and point the user at a shared schema that many other enterprise users can also access.
See Also:
Oracle Database Enterprise User Security Administrator's Guide for more information about managing enterprise usersAs part of designing your application, you need to determine the types of users who will be working with the application and the level of access that they need to accomplish their designated tasks. You must categorize these users into role groups, and then determine the privileges that must be granted to each role.
Topics:
End users are typically granted object privileges. An object privilege allows a user to perform a particular action on a specific table, view, sequence, procedure, function, or package.
Table 8-3 summarizes the object privileges available for each type of object.
Table 8-3 How Privileges Relate to Schema Objects
Object Privilege | Applies to Table? | Applies to View? | Applies to Sequence? | Applies to Procedure?Foot 1 |
---|---|---|---|---|
|
Yes |
No |
Yes |
No |
|
Yes |
Yes |
No |
No |
|
No |
No |
No |
Yes |
|
YesFoot 2 |
No |
No |
No |
|
Yes |
Yes |
No |
No |
|
YesFootref 2 |
No |
No |
No |
|
Yes |
YesFoot 3 |
Yes |
No |
|
Yes |
Yes |
No |
No |
Footnote 1 Standalone stored procedures, functions, and public package constructs
Footnote 2 Privilege that cannot be granted to a role
Footnote 3 Can also be granted for snapshots
See also "Auditing Object Actions" for detailed information about how schema objects can be audited.
As you implement and test your application, you should create each necessary role. Test the usage scenario for each role to ensure that the users of your application will have proper access to the database. After completing your tests, coordinate with the administrator of the application to ensure that each user is assigned the proper roles.
Table 8-4 lists the SQL statements permitted by the object privileges shown in Table 8-3.
Table 8-4 SQL Statements Permitted by Database Object Privileges
Object Privilege | SQL Statements Permitted |
---|---|
|
|
|
|
References to public package variables |
|
|
|
|
|
|
|
SQL statements using a sequence |
See "About Privileges and Roles" for a discussion of object privileges. See also "Auditing Object Actions" for detailed information about how SQL statements can be audited.
Database administrators can manage security for their applications in a variety of ways, such as handling bad packets from protocol errors, configuring the maximum number of authentication errors, and managing the database version banner.
Configuration of the Maximum Number of Authentication Attempts
Configuring Banners for Unauthorized Access and Auditing User Actions
Networking communication utilities such as Oracle Call Interface (OCI) or Two-Task Common (TTC) can generate a large disk file containing the stack trace and heap dump when the server receives a bad packet, out-of-sequence packet, or a private or an unused remote procedure call.
Typically, this disk file can grow quite large. An intruder can potentially cripple a system by repeatedly sending bad packets to the server, which can result in disk flooding and denial of service. An unauthenticated client can also mount this type of attack.
You can prevent these attacks by setting the SEC_PROTOCOL_ERROR_TRACE_ACTION
initialization parameter to one of the following values:
None
: Configures the server to ignore the bad packets and does not generate any trace files or log messages. Use this setting if the server availability is overwhelmingly more important than knowing that bad packets are being received.
For example:
SEC_PROTOCOL_ERROR_TRACE_ACTION = None
Trace
(default setting): Creates the trace files, but it is useful for debugging purposes, for example, when a network client is sending bad packets as a result of a bug.
For example:
SEC_PROTOCOL_ERROR_TRACE_ACTION = Trace
Log
: Writes a short, one-line message to the server trace file. This choice balances some level of auditing with system availability.
For example:
SEC_PROTOCOL_ERROR_TRACE_ACTION = Log
Alert
: Sends an alert message to a database administrator or monitoring console.
For example:
SEC_PROTOCOL_ERROR_TRACE_ACTION = Alert
After Oracle Database detects a client or server protocol error, it must continue execution. However, this could subject the server to further bad packets, which could lead to disk flooding or denial-of-service attacks.
To control the further execution of a server process when it is receiving bad packets from a potentially malicious client, set the SEC_PROTOCOL_ERROR_FURTHER_ACTION
initialization parameter to one of the following values:
Continue
(default setting): Continues the server execution. However, be aware that the server may be subject to further attacks.
For example:
SEC_PROTOCOL_ERROR_FURTHER_ACTION = Continue
Delay,
m
: Delays the client m
seconds before the server can accept the next request from the same client connection. This setting prevents malicious clients from excessively using server resources while legitimate clients experience a degradation in performance but can continue to function.
For example:
SEC_PROTOCOL_ERROR_FURTHER_ACTION = Delay,3
Drop,
n
: Forcefully terminates the client connection after n
bad packets. This setting enables the server to protect itself at the expense of the client, for example, loss of a transaction. However, the client can still reconnect, and attempt the same operation again.
For example:
SEC_PROTOCOL_ERROR_FURTHER_ACTION = Drop,10
With Oracle Database, a server process is first started, and then the client authenticates with this server process. An intruder could start a server process first, and then issue an unlimited number of authenticated requests with different user names and passwords in an attempt to gain access to the database.
You can limit the number of failed login attempts for application connections by setting the SEC_MAX_FAILED_LOGIN_ATTEMPTS
initialization parameter to restrict the number of authentication attempts on a connection. After the specified number of authentication attempts fail, the database process drops the connection. By default, SEC_MAX_FAILED_LOGIN_ATTEMPTS
is set to 10.
Remember that the SEC_MAX_FAILED_LOGIN_ATTEMPTS
initialization parameter is designed to prevent potential intruders from attacking your applications; it does not apply to valid users. The sqlnet.ora
INBOUND_CONNECT_TIMEOUT
parameter and the FAILED_LOGIN_ATTEMPTS
initialization parameter also restrict failed logins, but the difference is that these two parameters only apply to valid user accounts.
For example, to limit the maximum attempts to 5, set SEC_MAX_FAILED_LOGIN_ATTEMPTS
as follows in the init
sid
.ora
initialization parameter file:
SEC_MAX_FAILED_LOGIN_ATTEMPTS = 5
Detailed product version information should not be accessible before a client connection (including an Oracle Call Interface client) is authenticated. An intruder could use the database version to find information about security vulnerabilities that may be present in the database software.
To restrict the display of the database version banner to unauthenticated clients, set the SEC_RETURN_SERVER_RELEASE_BANNER
initialization parameter in the init
sid
.ora
initialization parameter file to either TRUE
or FALSE
.
By default, SEC_RETURN_SERVER_RELEASE_BANNER
is set to FALSE
.
For example, if you set it to TRUE
, then Oracle Database displays the full correct database version:
Oracle Database 12c Enterprise Edition Release 12.1.0.0 - Production
In the future, if you install Oracle Database Release 12.2.0.2, for example, it will display the following banner:
Oracle Database 12c Enterprise Edition Release 12.2.0.2 - Production
However, if in that same release, you set it to NO
, then Oracle Database restricts the banner to display the following fixed text starting with Release 12.2:
Oracle Database 12c Release 12.2.0.0.0 - Production
You should create and configure banners to warn users against unauthorized access and possible auditing of user actions. The notices are available to the client application when it logs into the database.
To configure these banners to display, set the following sqlnet.ora
parameters on the database server side to point to a text file that contains the banner information:
By default, these parameters are not set. In addition, be aware that there is a 512-byte limitation for the number of characters used for the banner text.
After you set these parameters, the Oracle Call Interface application must use the appropriate OCI APIs to retrieve these banners and present them to the end user.