The DBMS must protect audit data records and integrity by using cryptographic mechanisms.

From Oracle Database 12c Security Technical Implementation Guide

Part of SRG-APP-000126-DB-000171

Associated with: CCI-001350

SV-76157r2_rule The DBMS must protect audit data records and integrity by using cryptographic mechanisms.

Vulnerability discussion

Protection of audit records and audit data is of critical importance. Cryptographic mechanisms are the industry-established standard used to protect the integrity of audit data. An example of a cryptographic mechanism is the computation and application of a cryptographic-signed hash using asymmetric cryptography.Non-repudiation protects individuals against later claims by an author of not having performed a particular action, a sender of not having transmitted a message, a receiver of not having received a message, or a signatory of not having signed a document.

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Review the DBMS settings to determine whether audit logging is configured to produce logs consistent with the amount of space allocated for logging. If auditing will generate excessive logs so that they may outgrow the space reserved for logging, this is a finding. If file-based auditing is in use, check that the file(s) is/are encrypted by the operating system/file system. If not, this is a finding If standard, table-based auditing is used: The audit logs are written to a table called AUD$, and if a Virtual Private Database is deployed, we also create a table called FGA_LOG$. First check the current location of the audit trail tables. CONN / AS SYSDBA SELECT table_name, tablespace_name FROM dba_tables WHERE table_name IN ('AUD$', 'FGA_LOG$') ORDER BY table_name; TABLE_NAME TABLESPACE_NAME ------------------------------ ------------------------------ AUD$ SYSTEM FGA_LOG$ SYSTEM If the tablespace name is SYSTEM, the table needs to be relocated to its own tablespace. Ensure that adequate space is allocated to that tablespace. If Unified Auditing is used: Audit logs are written to tables in the AUDSYS schema. The default tablespace for AUDSYS is USERS. A separate tablespace should be created to contain audit data. Ensure that adequate space is allocated to that tablespace.

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For file-based auditing (OS, XML, or XML,EXTENDED), implement operating system/file system encryption for the audit file. For table-based auditing, deploy the audit tables in an encrypted tablespace. - - - - - If auditing is not enabled, use the following steps to enable auditing. sqlplus connect as sysdba Turn on Oracle audit a. If the database uses an spfile SQL> alter system set audit_trail=DB,EXTENDED scope=spfile ; System altered. b. if database uses pfile, modify init.ora directly. For these changes to take place, the database must be restarted. Next we create an encrypted tablespace. Before tablespaces can be encrypted or decrypted, a master encryption key must be generated or set. The tablespace master encryption key is stored in an external security module and is used to encrypt the TDE tablespace encryption keys. - - - - - Caution: Do not attempt to encrypt Oracle internal objects such as the SYSTEM, SYSAUX, UNDO, or TEMP tablespaces. Oracle does not support this with TDE. When moving AUD$ to a new tablespace, be aware that associated LOB objects will also need to be moved. Finally, when upgrading, the AUD$ table and LOBs will need to be moved back to the SYSTEM tablespace or the upgrade will fail. - - - - - Check to ensure that the ENCRYPTION_WALLET_LOCATION (or WALLET_LOCATION) parameter in the sqlnet.ora file points to the correct software wallet location. (Note: This assumes that a single sqlnet.ora file, in the default location, is in use. Please see the supplemental file "Non-default sqlnet.ora configurations.pdf" for how to find multiple and/or differently located sqlnet.ora files.) For example: ENCRYPTION_WALLET_LOCATION= (SOURCE=(METHOD=FILE)(METHOD_DATA= (DIRECTORY=/app/wallet))) If the ENCRYPTION_WALLET_LOCATION parameter is not set, then it attempts to use the keystore in the location that is specified by the parameter WALLET_LOCATION. If the WALLET_LOCATION parameter is also not set, then Oracle Database looks for a keystore at the default database location, which is ORACLE_BASE/admin/DB_UNIQUE_NAME/wallet or ORACLE_HOME/admin/DB_UNIQUE_NAME/wallet. (DB_UNIQUE_NAME is the unique name of the database specified in the initialization parameter file.) When the keystore location is not set in the sqlnet.ora file, then the V$ENCRYPTION_WALLET view displays the default location. Can check the location and status of the keystore in the V$ENCRYPTION_WALLET view. Oracle Database 12c Release 1 (12.1) uses the same master encryption key for both TDE column encryption and TDE tablespace encryption. When issuing the ALTER SYSTEM SET ENCRYPTION KEY command, a unified master encryption key is created for both TDE column encryption and TDE tablespace encryption. Resetting the Tablespace Master Encryption Key Oracle Database 12c Release 1 (12.1) uses a unified master encryption key for both TDE column encryption and TDE tablespace encryption. When resetting (rekeying) the master encryption key for TDE column encryption, the master encryption key for TDE tablespace encryption also gets reset. The ALTER SYSTEM SET ENCRYPTION KEY command resets the tablespace master encryption key. Before creating an encrypted tablespace, the Oracle wallet containing the tablespace master encryption key must be open. The wallet must also be open before accessing data in an encrypted tablespace. The security administrator needs to open the Oracle wallet after starting the Oracle instance. A restart of the Oracle instance requires the security administrator to open the wallet again. The security administrator also needs to open the wallet before performing database recovery operations. This is because background processes may require access to encrypted redo and undo logs. When performing database recovery, the wallet must be opened before opening the database. This is illustrated in the following statements: SQL> STARTUP MOUNT; SQL> ALTER SYSTEM SET ENCRYPTION WALLET OPEN IDENTIFIED BY "password"; SQL> ALTER DATABASE OPEN; Can also choose to use auto logon wallets if the environment does not require the extra security provided by a wallet that needs to be explicitly opened; however, this is not the recommended practice. Creating the wallet/keystore SQL> ADMINISTER KEY MANAGEMENT CREATE KEYSTORE '/app/wallet' IDENTIFIED BY password; keystore altered. Set the TDE Master Encryption Key in the Software Keystore SQL> ADMINISTER KEY MANAGEMENT SET KEY IDENTIFIED BY password WITH BACKUP USING 'backup_identifier'; keystore altered. Creating an Encrypted Tablespace The CREATE TABLESPACE command enables the creation of an encrypted tablespace. The permanent_tablespace_clause enables choosing the encryption algorithm and the key length for encryption. The ENCRYPT keyword in the storage_clause encrypts the tablespace. The following syntax illustrates this: CREATE [ BIGFILE | SMALLFILE ] { permanent_tablespace_clause | temporary_tablespace_clause | undo_tablespace_clause } ; Where, permanent_tablespace_clause=TABLESPACE , ENCRYPTION [USING algorithm] storage_clause Where, storage_clause=[ENCRYPT] where: The encryption algorithm can have one of the following values: 3DES168 AES128 AES192 AES256 The key lengths are included in the names of the algorithms themselves. If no encryption algorithm is specified, the default encryption algorithm is used. The default encryption algorithm is AES128. Note: The ENCRYPTION keyword in the permanent_tablespace_clause is used to specify the encryption algorithm. The ENCRYPT keyword in the storage_clause actually encrypts the tablespace. For security reasons, a tablespace cannot be encrypted with the NO SALT option. Commands to create Encrypted Tablespace CREATE TABLESPACE securespace DATAFILE '/home/user/oradata/secure01.dbf' SIZE 150M ENCRYPTION USING '3DES168' DEFAULT STORAGE(ENCRYPT); This creates a tablespace called securespace2 using an algorithm of 3DES168. Cannot encrypt an existing tablespace. However, can import data into an encrypted tablespace using the Oracle Data Pump utility. Can also use SQL commands like CREATE TABLE...AS SELECT...or ALTER TABLE...MOVE... to move data into an encrypted tablespace. The CREATE TABLE...AS SELECT... command enables the creation of a table from an existing table. The ALTER TABLE...MOVE... command enables the move of a table into the encrypted tablespace. Then we move the sys.aud$ from system tablespace to securespace tablespace. SQL> exec DBMS_AUDIT_MGMT.SET_AUDIT_TRAIL_LOCATION(audit_trail_type => DBMS_AUDIT_MGMT.AUDIT_TRAIL_AUD_STD, audit_trail_location_value => 'securespace'); PL/SQL procedure successfully completed. Then check the tablespace the table is stored in. SQL> SELECT table_name, tablespace_name FROM dba_tables WHERE table_name ='AUD$'; TABLE_NAME TABLESPACE_NAME ---------------------------- ------------------------ AUD$ SECURESPACE

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