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Auditing Techniques for Oracle
Database 11g
Carl Dudley
University of Wolverhampton, UK
UKOUG Committee
Oracle ACE Director
[email protected]
Carl Dudley – University of Wolverhampton
Auditing Techniques for Oracle Database 11g
Working with Oracle since 1986
Oracle
DBA
Auditing
Overview
Working with Oracle since 1986
- OCP Oracle7, 8, 9, 10
Oracle Auditing
DBA of
Application
Oracle DBA - OCP Oracle7, 8, 9, 10
the Year
– 2002
Oracle DBA of the Year – 2002
Trigger-based
Auditing
Oracle ACE
Director Oracle ACE Director
Auditing
the sys
User
Regular
Presenter
Regular Presenter
at Oracle Conferences
at Oracle
Conferences
Standard Auditing
Consultant and Trainer
Fine-Grained Auditing
Technical Editor for a number of Oracle texts
Consultant and Trainer
Technical Editor for a UK
number
of Oracle texts
Oracle User Group Director
Managing the Audit Trail
UK Oracle User GroupMember
Director
of IOUC
Auditing Recommendations
Member of IOUC
Day job – University of Wolverhampton, UK
Day job – University of Wolverhampton, UK
2
Security – Main facets
A
Authentication
well known adage
/ Identification
about software development
—
Who
youit done right,
“You
canare
have
you can have it done fast,
you can have it done cheap
 Authorisation
Pick any two”
— What you can do/see
 A possible adage about database security
“You can have
high performance,
 Auditing
high security,
— What you did
high usability
• The what, when, who, where and how
Pick any one”
 Security should be database-centric, not application centric
 There is now a focus on the database
3
Auditing Overview
 What to audit
 How to audit
 How to use audit records
 Handling performance issues
 Auditing can also show work patterns, frequency of use etc.
 Auditing allows you to know when you have been robbed and by whom
— Data can be 'stolen' without anyone knowing
 Perform selective auditing
— Blanket auditing can have a negative performance effect
— Also produces massive, difficult to handle, audit trails
 Last phase in security cycle – never dispense with it
4
Auditing Techniques for Oracle Database 11g
Auditing Overview
Application Auditing
Trigger-based Auditing
Auditing the sys User
Standard Auditing
Fine-Grained Auditing
Managing the Audit Trail
Auditing Recommendations
5
Application Auditing
 Programmed into an application
— Often implemented in third party applications
 Often done for portability across DBMSs, or when database auditing is not
well understood
 All aspects can be audited
— Extremely flexible and extensible
 Maintenance of the code can be onerous
 Big applications are often targets for hackers
 Application can be bypassed rendering auditing useless
— It’s application centric
6
Application Auditing Example
CREATE TABLE emp_under_audit AS SELECT * FROM empcopy;
 Create a table (aud_emp) designed to capture audit information for the
emp_under_audit table
CREATE TABLE aud_emp (
username
VARCHAR2(30)
,action
VARCHAR2(12)
,empno
NUMBER(4),
,column_name VARCHAR2(255)
,call_stack VARCHAR2(4000)
,client_id
VARCHAR2(255)
,old_value
VARCHAR2(25)
,new_value
VARCHAR2(25)
,action_date DATE);
7
Application Auditing Example (continued)
 Create a procedure to generate auditing information
CREATE OR REPLACE PROCEDURE proc_audit_emp (
pi_username
IN VARCHAR2
,pi_action
IN VARCHAR2
,pi_empno
IN NUMBER
,pi_column_name IN VARCHAR2
,pi_old_value
IN VARCHAR2
,pi_new_value
IN VARCHAR2)
AS
BEGIN
INSERT INTO aud_emp
(username,action,empno,column_name,call_stack,
client_id,old_value,new_value,action_date)
VALUES (pi_username
,pi_action
,pi_empno
,pi_column_name
,dbms_utility.format_call_stack
,sys_context('userenv','client_identifier')
,pi_old_value
,pi_new_value
,sysdate);
END;
8
Application Auditing Example (continued)
 Create a procedure to show and format the auditing information
CREATE OR REPLACE PROCEDURE proc_format_aud_emp AS
BEGIN
FOR r IN (SELECT *
FROM aud_emp
ORDER BY action_date DESC)
LOOP
dbms_output.put_line('User:
'||r.username);
dbms_output.put_line('Client ID: '||r.client_id);
dbms_output.put_line('Action:
'||r.action);
dbms_output.put_line('Empno:
'||r.empno);
dbms_output.put_line('Column:
'||r.column_name);
dbms_output.put_line('Old Value: '||r.old_value);
dbms_output.put_line('New Value: '||r.new_value);
dbms_output.put_line('Date:
'||
TO_CHAR(r.action_date,'MON-DD-YYYY HH24:MI'));
END LOOP;
END;
9
Application Auditing Example (continued)
 Create an application procedure that is audited
CREATE OR REPLACE PROCEDURE proc_update_sal(
pi_empno IN NUMBER,
pi_salary IN NUMBER)
AS
v_old_sal VARCHAR2(25);
BEGIN
SELECT sal INTO v_old_sal FROM emp_under_audit
WHERE empno = p_empno
FOR UPDATE;
UPDATE emp_under_audit SET sal = pi_salary
WHERE empno = pi_empno;
proc_audit_emp
(pi_username => user
,pi_action => 'UPDATE'
,pi_empno => pi_empno
,pi_column_name => 'SAL'
,pi_old_value => v_old_sal
,pi_new_value => pi_salary);
END;
/
10
Application Auditing Example (continued)
 Run application, executing the update procedure and auditing the changes
BEGIN
proc_update_sal(p_empno => 7369,p_salary => 950);
proc_format_aud_emp;
END;
/
 Show the resultant call stack
SELECT username,call_stack FROM aud_emp;
USERNAME CALL_STACK
-------- ------------------------------------SCOTT
----- PL/SQL Call Stack ----object
line object
handle
number name
664B1434
1 anonymous block
6A1DFC34
10 procedure SCOTT.PROC_AUDIT_EMP
66614FA0
11 procedure SCOTT.PROC_UPDATE_SAL
6651D620
2 anonymous block
11
Application Auditing Example (continued)
 Show the captured audit information
— The Client ID returns the IP_address if user was remote
— Could capture much more about the user context
BEGIN
proc_format_aud_emp;
END;
/
User:
Client ID:
Action:
Empno:
Column:
Old Value:
New Value:
Date:
SMITH
127.0.0.1
UPDATE
7369
SAL
800
950
SEP-07-2012 18:37
12
Auditing Techniques for Oracle Database 11g
Auditing Overview
Application Auditing
Trigger-based Auditing
Auditing the sys User
Standard Auditing
Fine-Grained Auditing
Managing the Audit Trail
Auditing Recommendations
13
Trigger-based Auditing
 Database centric – very popular
— Sometimes called value-based auditing
 Can be used on INSERT, UPDATE, DELETE events (but not SELECTs)
 Transparent to all applications
 Flexible and extensible
 Do not always fire
— Do not fire on TRUNCATE
 Cannot receive parameters – restricted to column values
 Need to be created for each and every object
— Could call common procedures
14
Trigger-based Auditing – Simple Example
 Capture salary changes, who made the change and when using a simple
trigger
CREATE TRIGGER trg_a_idu_r_emp_sal
AFTER INSERT OR DELETE OR UPDATE OF sal ON emp
FOR EACH ROW
BEGIN
IF (:NEW.sal > :OLD.sal * 1.10)
THEN INSERT INTO emp_sal_audit VALUES (:OLD.empno
,:OLD.sal
,:NEW.sal
,user
,sysdate);
END IF;
END;
/
— Triggers cannot capture the triggering statement
— Cannot be used to define alert actions
— Fine-Grained auditing may be a better option
15
Trigger to Populate Audit table
 Trigger fires on updates of sal
— Executes proc_audit_emp to populate the pre-constructed audit table
(aud_emp)
CREATE OR REPLACE TRIGGER trg_b_u_r_emp_copy_sal
BEFORE UPDATE OF sal
ON emp_copy
FOR EACH ROW
DECLARE
BEGIN
proc_audit_emp (p_username => user,
,p_action => 'UPDATE'
,p_empno => :OLD.empno
,p_column_name => 'SAL'
,p_old_value => TO_CHAR(:OLD.sal)
,p_new_value => TO_CHAR(:NEW.sal));
END;
/
16
Firing the Audit Trigger
 Smith performs an update which fires the trigger
SMITH> UPDATE scott.emp_copy
2 SET sal = sal*1.1
3 WHERE job = 'ANALYST';
 The call stack shows the trigger firing
SCOTT> SELECT DISTINCT call_stack FROM aud_emp;
CALL_STACK
---------------------------------------------------- PL/SQL Call Stack ----object
line object
handle
number name
665C3F84
1 anonymous block
6675288C
10 procedure SCOTT.PROC_AUDIT_EMP
6A297C30
3 SCOTT.TRG_B_U_R_EMP_COPY_SAL
17
The Triggered Audit Records
 The auditing information shows two records suffering update
SCOTT> BEGIN
2
proc_format_aud_emp;
3 END;
4 /
User:
Client ID:
Action:
Empno:
Column:
Old Value:
New Value:
Date:
User:
Client ID:
Action:
Empno:
Column:
Old Value:
New Value:
Date:
SMITH
UPDATE
7902
SAL
3000
3300
SEP-07-2012 19:37
SMITH
UPDATE
7788
SAL
3000
3300
SEP-07-2012 19:37
18
Handling Rollback - Autonomous Transactions
 Scenario
— User makes an update, inspects values and then rolls back the transaction
— Records in the auditing table will also be rolled back
• Loss of auditing information
 Cannot place COMMIT in the trigger
— But can use Autonomous Transactions
• Allows actions of triggers to commit independently of the triggering
statement
• Preserves the auditing information on rollback
19
Handling Rollback – Autonomous Transactions
(continued)
 All updates will be audited
CREATE OR REPLACE PROCEDURE proc_audit_emp (
p_username
IN VARCHAR2
,p_action
IN VARCHAR2
,p_empno
IN NUMBER
,p_column_name IN VARCHAR2
,p_old_value
IN VARCHAR2
,p_new_value
IN VARCHAR2)
AS
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
INSERT INTO aud_emp
(username,action,empno,column_name,call_stack,
client_id,old_value,new_value,action_date)
VALUES (p_username
,p_action
,p_empno
,p_column_name
,dbms_utility.format_call_stack
,sys_context('userenv','client_identifier')
,p_old_value
,p_new_value
,sysdate);
COMMIT;
END;
20
Auditing Techniques for Oracle Database 11g
Auditing Overview
Application Auditing
Trigger-based Auditing
Auditing the sys User
Standard Auditing
Fine-Grained Auditing
Managing the Audit Trail
Auditing Recommendations
21
Mandatory Database Auditing
 Mandatory Auditing always records
— Startup
— Shutdown
— User logins and logoffs with SYSDBA and SYSOPER privileges
• Shows if an administrator has disabled auditing
AUDIT_TRAIL = FALSE (or NONE)
 Records must be stored in the operating system because database not
available on starting or stopping
— On Windows in the Event Logs
— On Linux and unix in $ORACLE_HOME/rdbms/audit
22
Auditing the SYS User with AUDIT_SYS_OPERATIONS
ALTER SYSTEM SET AUDIT_SYS_OPERATIONS = TRUE
SCOPE = SPFILE;
 Actions by users having SYSDBA or SYSOPER are written to OS files (XML
as appropriate), not the database
— All successful sys top-level SQL actions are audited
• Can be seen in the Windows Event Viewer (not in aud$)
— These database users should not have access to the audit records
 The parameter is deliberately not dynamic
— Database must be 'bounced' to change its value
— Stops the DBA from simply turning off auditing, perform a malicious action
and then turning auditing back on
• Having to bounce the database captures the disabling of the auditing
23
Example sys Audit
CONNECT / AS SYSDBA
ALTER SYSTEM FLUSH SHARED_POOL;
UPDATE scott.emp SET sal=1000 WHERE ename='SCOTT';
 When sys auditing is enabled, both the ALTER SYSTEM and UPDATE
statements are displayed in the OS audit file or event log:
Audit trail: LENGTH: '177' ACTION :[7] 'CONNECT'
DATABASE USER:[1] '/' PRIVILEGE :[6] 'SYSDBA' CLIENT
USER:[10] 'UNV\in8308' CLIENT TERMINAL:[14] 'WXPLTITR12680' STATUS:[1] '0' DBID:[10] '1318485259' .
Audit trail: LENGTH: '201' ACTION :[30] 'ALTER SYSTEM
FLUSH SHARED_POOL' DATABASE USER:[1] '/' PRIVILEGE
:[6] 'SYSDBA' CLIENT USER:[10] 'UNV\in8308' CLIENT
TERMINAL:[14] 'WXPLT-ITR12680' STATUS:[1] '0'
DBID:[10] '1318485259' .
Audit trail: LENGTH: '220' ACTION :[49] 'UPDATE
scott.emp SET sal=1000 WHERE ename='SCOTT'' DATABASE
USER:[1] '/' PRIVILEGE :[6] 'SYSDBA' CLIENT USER:[10]
'UNV\in8308' CLIENT TERMINAL:[14] 'WXPLT-ITR12680'
STATUS:[1] '0' DBID:[10] '1318485259' .
24
Auditing
Auditing Overview
Application Auditing
Trigger-based Auditing
Auditing the sys User
Standard Auditing
Fine-Grained Auditing
Managing the Audit Trail
Auditing Recommendations
25
Values of AUDIT_TRAIL for Standard Auditing
Value of
AUDIT_TRAIL
Auditing Activity
FALSE (Default)
(NONE on Oracle10g)
No standard auditing activity
OS
Records are written to OS
Do this for same reasons as for AUDIT_SYS_OPERATIONS
Accessible when database is down
XML
(or XML,EXTENDED)
Records written as XML
New view (V$XML_AUDIT_TRAIL ) shows these records in
relational format and makes them 'queryable' via SQL
EXTENDED causes audit of sql text and bind variable values
DB
(or DB,EXTENDED)
Records are written to a database table (sys.aud$)
Makes it easier to run reports
 The audit trail does not store data values
26
Setting Standard Auditing
ALTER SYSTEM SET AUDIT_TRAIL = DB,EXTENDED SCOPE = SPFILE;
 The parameter is deliberately not dynamic
— Database must be 'bounced' to change its value
— Set this value on database creation to avoid a database 'bounce' later
 If AUDIT_FILE_DEST is not specified, the default OS location is
— Solaris
$ORACLE_BASE/admin/$DB_UNIQUE_NAME/adump
— Windows
$ORACLE_BASE\admin\$DB_UNIQUE_NAME\adump
27
Scoping Audit Activity – Standard Auditing
 Specific objects
 Executing procedures
 Use of a system privilege
 Specific users
 Successful and/or unsuccessful actions
 Per action or per session (per session is not a realistic option on 11g)
 Allows focussing of auditing activity
— Important to fine tune this to avoid performance and storage issues
 Allows monitoring of privileged users – DBAS etc.
28
Auditing Connections
 Need to know who and when
— Most outages are down to human activity
— Not easy for users of applications using connection pools
 Generates lots of records
— Need adequate disk space and purging policy
 To audit connections, two criteria must be set
— Ensure AUDIT_TRAIL = DB,EXTENDED
— When connected as the user system, issue the command
AUDIT SESSION;
AUDIT SESSION BY scott,smith;
— Audits connections only for scott and smith
 Not much defence for not having this information
29
Auditing Connections (continued)
 Script to report on audit of user logons and logoffs
BEGIN
FOR r IN
(SELECT username
,action_name
,TO_CHAR(timestamp, 'DD-MON HH24:MI') LOGON
,TO_CHAR(logoff_time, 'DD-MON HH24:MI') LOGOFF
,priv_used
,comment_text
FROM dba_audit_trail)
LOOP
dbms_output.put_line('User:
'||r.username);
dbms_output.put_line('Action:
'||r.action_name);
dbms_output.put_line('Logon:
'||r.LOGON);
dbms_output.put_line('Logoff:
'||r.LOGOFF);
dbms_output.put_line('Priv:
'||r.priv_used);
dbms_output.put_line('Comments: '||r.comment_text);
dbms_output.put_line('-----End of audit record-----');
END LOOP;
END;
30
Audit Report Output
 User scott has created a session and then exited almost immediately
SYS>/
User:
SCOTT
Action:
LOGON
Logon:
12-SEP 09:24
Logoff:
User has yet to logoff
Priv:
CREATE SESSION
Comments:
Authenticated by: DATABASE; Client address:
(ADDRESS=(PROTOCOL=tcp)(HOST=169.254.207.135)(PORT=2817))
------End of audit record-----PL/SQL procedure successfully completed.
SYS> /
User:
SCOTT
Action:
LOGOFF
Logon:
12-SEP 09:24
Logoff:
12-SEP 09:25
Priv:
CREATE SESSION
Comments:
Authenticated by: DATABASE; Client address:
(ADDRESS=(PROTOCOL=tcp)(HOST=169.254.207.135)(PORT=2817))
---------End of audit record--------— On Oracle11g you may see DBSNMP and SYSMAN activity
31
Statement Auditing
 The use of any kind of SQL statement can be audited
— Can be based on whether the statement is successful, unsuccessful or both
 Examples of auditing based on statements affecting types of objects
AUDIT ROLE,TABLE;
— Audits CREATE, ALTER, DROP of any role or table
AUDIT CREATE TABLE;
— Audits CREATE TABLE statements
AUDIT ALTER TABLE WHENEVER NOT SUCCESSFUL;
— Audits ALTER TABLE statements only when they are unsuccessful
32
Statement Auditing (continued)
 Audit all unsuccessful SELECT, INSERT, DELETE statements on all tables
and any unsuccessful attempt at executing a procedure
AUDIT SELECT TABLE, INSERT TABLE, DELETE TABLE,
EXECUTE PROCEDURE BY ACCESS WHENEVER NOT SUCCESSFUL;
 Can be specified on a per user basis
AUDIT DELETE TABLE BY tt BY ACCESS;
33
Tracking Statement Auditing
 Statement level auditing is shown in dba_stmt_audit_opts
AUDIT CREATE EXTERNAL JOB BY tt;
SELECT * FROM dba_stmt_audit_opts;
USER_NAME PROXY_NAME AUDIT_OPTION
--------- ---------- ------------------:
:
DROP ANY TABLE
CREATE EXTERNAL JOB
TT
CREATE EXTERNAL JOB
:
:
SUCCESS
---------:
BY SESSION
BY SESSION
BY SESSION
:
FAILURE
---------:
BY SESSION
BY SESSION
BY SESSION
:
NOAUDIT CREATE EXTERNAL JOB;
SELECT * FROM dba_stmt_audit_opts;
USER_NAME PROXY_NAME AUDIT_OPTION
--------- ---------- ------------------:
:
DROP ANY TABLE
TT
CREATE EXTERNAL JOB
:
:
SUCCESS
---------:
BY SESSION
BY SESSION
:
FAILURE
---------:
BY SESSION
BY SESSION
:
34
Privilege-Based Auditing
 Examples of auditing on types of privileges
AUDIT DELETE ANY TABLE;
— Audits any successful or unsuccessful action that depends on the DELETE
ANY TABLE privilege
AUDIT UPDATE ANY TABLE BY ACCESS WHENEVER NOT SUCCESSFUL;
— Audits each unsuccessful use of the UPDATE ANY TABLE privilege
• Default is BY SESSION
 The AUDIT SYSTEM privilege is required by any user that sets up system or
privilege-based auditing
— This would normally be the security administrator and no-one else
35
Object-based Auditing
 Object owners and administrators can set object-based auditing
— AUDIT ANY allows auditing to be set on any object
 Examples of auditing on specific objects
— Audit successful attempts to query the emp table on a session basis
AUDIT SELECT ON emp WHENEVER SUCCESSFUL;
— Audit all unsuccessful attempts to query scott's dept table by access
AUDIT SELECT, INSERT, DELETE ON scott.dept
BY ACCESS WHENEVER NOT SUCCESSFUL;
36
Object-based Auditing (continued)
Object
Option
ALTER
Table
X
View
--
Seq
X
Proc
Func
Pkg
--
AUDIT
X
X
X
X
X
COMMENT
X
X
--
--
DELETE
X
X
--
EXECUTE
--
--
FLASHBACK
X
GRANT
Lib
--
Object
Type
X
Context
--
X
--
X
X
X
--
--
--
--
--
X
--
--
--
--
--
X
--
--
X
--
--
X
--
--
--
--
--
--
--
X
X
X
X
--
X
X
X
X
INDEX
X
--
--
--
X
--
--
--
--
INSERT
X
X
--
--
X
--
--
--
--
LOCK
X
X
--
--
X
--
--
--
--
READ
--
--
--
--
--
X
--
--
--
WRI
????
RENAME
X
X
--
--
--
--
--
--
--
REF
SELECT
Obsolete, do not use
X
X
X
--
X
--
--
--
--
UPDATE
X
--
X
--
--
--
--
CRE
????
X
--
Mview
X
Dir
--
37
Object Level Auditing
 Cannot be specified on a per user basis
AUDIT DELETE,UPDATE ON SCOTT.EMP WHENEVER NOT SUCCESSFUL;
AUDIT SELECT ON SCOTT.EMP BY ACCESS;
AUDIT INSERT ON SCOTT.EMP BY ACCESS WHENEVER SUCCESSFUL;
SELECT * FROM dba_obj_audit_opts;
OBJECT_
OWNER OBJECT_NAME TYPE
ALT AUD COM DEL GRA IND INS LOC REN SEL UPD REF EXE CRE REA WRI FBK
----- ----------- ------- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --- --SCOTT EMP
TABLE
-/- -/- -/- -/S -/- -/- A/- -/- -/- A/A -/S -/- -/- -/- -/- -/- -/-
AUDIT ALL ON dept;
— Audits all possible options on the object
NOAUDIT ALL ON dept;
— Removes EVERY audit option on the object
38
BY SESSION vs BY ACCESS
 Originally, BY SESSION created one audit record for statements causing
the same auditing activity
— BY ACCESS creates audit record each time an auditable statement is run
 On Oracle 11g BY SESSION causes auditing as many times as BY ACCESS
but records less information
— Still remains as default
 Oracle recommend to use BY ACCESS
— Similar overheads but more information
39
Monitoring Object Auditing
 Status of objects being audited
SELECT upd "Update Option"
FROM dba_obj_audit_opts
WHERE object_name IN ('DEPT','EMP');
OBJECT_NAME
----------DEPT
EMP
Update Option
------------A/S/A
S = by session
A = by access
- = no auditing
First character shows if auditing is
enabled for successful attempts
Character after the '/' shows if auditing is
enabled for unsuccessful attempts
 Object auditing in audit trail
SELECT ses_actions,returncode FROM dba_audit_object;
SES_ACTIONS
RETURNCODE
---------------- ------------------F-----913
---F-----------913
---------S-----0
---S-----------0
delete
select
DELETE FROM emp WHERE empno =
(SELECT * FROM emp
WHERE ename = 'x');
ORA-00913: too many values
DELETE FROM emp WHERE empno =
(SELECT empno FROM emp
WHERE ename = 'x');
40
Monitoring System Wide Auditing
 Show auditing status of user logins with dba_stmt_audit_opts
SELECT * FROM dba_stmt_audit_opts;
USER_NAME PROXY_NAME AUDIT_OPTION
SUCCESS
FAILURE
--------- ---------- -------------- --------- --------CREATE SESSION BY ACCESS BY ACCESS
 Show auditing status of system privileges with dba_priv_audit_opts
SELECT * FROM dba_priv_audit_opts;
USER_NAME PROXY_NAME PRIVILEGE
SUCCESS
FAILURE
--------- ---------- ---------------- --------- --------SELECT ANY TABLE BY ACCESS BY ACCESS
 The dba_common_audit_trail view shows all auditing information
— Includes Fine-Grained Auditing
41
Auditing the Audit Trail
 If ordinary users have access to sys.aud$ then that access needs to be
audited
AUDIT SELECT, INSERT, UPDATE, DELETE ON sys.aud$ BY ACCESS;
— Any actions performed by non-SYSDBA users will now be audited
 A simple SELECT on sys.aud$ will generate an audit record in aud$
— A DELETE of this audit record will succeed, but it will generate another
record of the delete operation
 Any records of DML performed on aud$ cannot be deleted by regular users
 Setting up this type of auditing acts as a safety feature, potentially
revealing unusual or unauthorized actions
42
The Auditing Views
STMT_AUDIT_OPTION_MAP
AUDIT_ACTIONS
ALL_DEF_AUDIT_OPTS
DBA_STMT_AUDIT_OPTS
DBA_PRIV_AUDIT_OPTS
DBA_OBJ_AUDIT_OPTS
USER_OBJ_AUDIT_OPTS
DBA_AUDIT_TRAIL
USER_AUDIT_TRAIL
DBA_AUDIT_OBJECT
USER_AUDIT_OBJECT
DBA_AUDIT_SESSION
USER_AUDIT_SESSION
DBA_AUDIT_STATEMENT
USER_AUDIT_STATEMENT
DBA_AUDIT_EXISTS
DBA_AUDIT_POLICIES
DBA_FGA_AUDIT_TRAIL
DBA_COMMON_AUDIT_TRAIL
Contains information about auditing option type codes.
Created by the SQL.BSQ script at CREATE DATABASE time.
Contains descriptions for audit trail action type codes
Contains default object-auditing options to be applied on object creation
Describes current system auditing options across system and by user
Describes current system privileges being audited across system and by user
Describes auditing options on all objects
The USER view shows auditing options on all objects owned by current user
Lists all audit trail entries
The USER view shows audit trail entries relating to current user.
Contains audit trail records for all objects in the system
The USER view lists audit trail records for statements concerning objects that
are accessible to the current user
Lists all audit trail records concerning CONNECT and DISCONNECT
The USER view lists all audit trail records concerning connections and
disconnections for the current user
Lists audit trail records concerning GRANT, REVOKE, AUDIT, NOAUDIT,
and ALTER SYSTEM statements throughout the database
, or for the USER view, issued by the user.
Lists audit trail entries produced by AUDIT NOT EXISTS
Shows all the auditing policies on the system.
Lists audit trail records for value-based auditing
Combines standard and fine-grained audit log records, and includes sys
and mandatory audit records written in XML format
43
Setting up Audit Information
 Trigger sets the client identifier for each session at login time
CREATE OR REPLACE TRIGGER trg_set_client_info
AFTER LOGON ON DATABASE
DECLARE
v_module v$session.module%TYPE;
BEGIN
SELECT module INTO v_module
FROM v$process p, v$session s
WHERE p.addr = s.paddr
AND s.audsid = USERENV('sessionid');
dbms_session.set_identifier(sys_context
('userenv','ip_address')
||' - '||v_module);
END;
/
— Could set many other criteria such as authentication method
44
Auditing Statements
 Example shows three SELECT statements that will generate audit records
— The statement issued by system will generate three audit records
CONN system/manager
SELECT ename,sal
FROM scott.emp
WHERE sal < (SELECT sal
FROM scott.emp
WHERE ename = 'WARD')
AND job = (SELECT job
FROM scott.emp
WHERE ename = 'WARD');
CONN scott/tiger
SELECT job FROM scott.emp;
SELECT empno FROM scott.emp;
45
Correlating Audit Records
CREATE OR REPLACE PROCEDURE format_aud
AS
BEGIN
FOR r IN (SELECT db_user
,client_id
,object_schema
,object_name
,extended_timestamp
,sql_text
,statementid
FROM dba_common_audit_trail
GROUP BY db_user
,statementid
,sql_text
The grouping of statementids will cause
,object_schema
the system statement to show as one entry
,object_name
,client_id
,extended_timestamp
ORDER BY extended_timestamp ASC)
LOOP
dbms_output.put_line('Who: '||r.db_user);
dbms_output.put_line('What: '||r.object_schema||'.'||r.object_name);
dbms_output.put_line('Where: '||r.client_id);
dbms_output.put_line('When: '
||TO_CHAR(r.extended_timestamp,'MON-DD HH24:MI'));
dbms_output.put_line('How:
'||r.sql_text);
dbms_output.put_line('--------------End of audit record--------------');
END LOOP;
END;
46
Correlated Output from the Audit Trail
 The system record shows only once
 SQLPLUS is shown as part of the identifier (set by the trigger)
Who: SYSTEM
What: SCOTT.EMP
Where: 127.0.0.1 - sqlplus.exe
When: SEP-2012 11:15
How:
SELECT ename,sal
FROM scott.emp
WHERE sal < (SELECT sal
FROM scott.emp
WHERE ename = 'WARD')
AND job = (SELECT job
FROM scott.emp
WHERE ename = 'WARD')
--------------End of audit Record-------------Who: SCOTT
What: SCOTT.EMP
Where: 127.0.0.1 - sqlplus.exe
When: SEP-2012 11:15
How:
SELECT job FROM scott.emp
--------------End of audit Record-------------Who: SCOTT
What: SCOTT.EMP
Where: 127.0.0.1 - sqlplus.exe
When: SEP-2012 11:15
How:
SELECT ename FROM scott.emp;
The SELECT statement is
captured because
AUDIT_TRAIL = DB,EXTENDED
47
Performance Impact of Audit
 With auditing
CREATE OR REPLACE PROCEDURE perf_test_aud
AS
BEGIN
FOR rec IN 1..50000
LOOP
FOR inner_rec IN (SELECT ename FROM scott.emp)
LOOP
NULL;
END LOOP;
END LOOP;
END;
/
EXEC perf_test_aud
Elapsed : 39.93 seconds
48
Performance Impact of Audit (continued)
 Disable auditing and then re-execute
NOAUDIT SELECT ON scott.emp;
CREATE OR REPLACE PROCEDURE perf_test_aud
AS
BEGIN
FOR rec IN 1 ..50000
LOOP
FOR inner_rec IN (SELECT ename FROM scott.emp)
LOOP
NULL;
END LOOP;
END LOOP;
END;
/
EXEC perf_test_aud
Elapsed : 12.26 seconds
49
Auditing Limitations
 Not able to show what data the user actually saw
— But captures SCN of the operation
— Could use Flashback based on the SCN to see the data
• Depends on UNDO_RETENTION
— Oracle Consultancy have Selective Audit as a 'full' solution
 Audit data persists after a rollback
 Audit is generated even when no rows affected
 Cannot audit on specific columns or conditions
 Fine-grained auditing gives extra possibilities
50
Auditing
Auditing Overview
Application Auditing
Trigger-based Auditing
Auditing the sys User
Standard Auditing
Fine-Grained Auditing
Managing the Audit Trail
Auditing Recommendations
51
Fine-Grained Auditing (FGA) Features
1. Boolean condition check
— Anything specified in SQL
— Comparison of function call results
2. Column sensitivity
3. Event Handler
4. SQL capture
 Conditional auditing helps to reduce unnecessary audits
 Business rule
— Employees should see only their own record
• Auditing on the table generates audit information for all SELECTs
• Sifting through the audit is cumbersome
52
Setting UP FGA
 FGA does not depend on any initialisation parameters
 Implement auditing for users accessing other employees' records
BEGIN
dbms_fga.add_policy(object_schema => 'SCOTT'
,object_name => 'EMPTAB_FGA'
,policy_name => 'fga_emp'
,audit_condition => 'ENAME != USER'
,audit_trail => dbms_fga.db +
dbms_fga.extended);
END;
 audit_trail will place audit in fga_log$ (with sql texts) (default)
— Can alternatively be specified as XML
 If audit_condition is left as NULL, the audit always happens
 Requires the use of the cost-based optimizer and generation of statistics
53
Generating FGA records
 Two statements using the emptab_fga table
SELECT sal,ename FROM scott.emptab_fga WHERE ename = 'SCOTT';
SAL ENAME
---------- ---------3000 SCOTT
SELECT sal,ename FROM scott.emptab_fga WHERE ename = 'SMITH';
SAL ENAME
---------- ---------2850 SMITH
— Only one entry is placed in the audit table (SMITH is not the user SCOTT)
Who: SCOTT
What: SCOTT.EMPTAB_FGA
Where: - sqlplusw.exe
When: Nov-09 12:52
How:
SELECT sal,ename FROM scott.emptab_fga WHERE ename = 'SMITH'
--------------End of audit record--------------
54
Fine Grained Auditing Features
 When AUDIT_TRAIL = DB or DB,EXTENDED, the FGA records are stored in
the fga_log$ table owned by sys by default
— Shown in dba_fga_audit_trail
— Also seen in dba_common_audit_trail with other auditing information
• Clearing out aud$ will not remove FGA records
 Fine-grained auditing goes beyond triggers
— Triggers incur a PL/SQL call for every row processed
• Create an audit record only when a relevant column is changed by DML
— FGA is not invoked for every row - only once for every policy
• Audit occurs when a specified column is either changed or used in
selection criteria
– Uncovers users who hope their actions will be masked because
they use the sensitive columns only in the selection criteria
55
Targeting Fine-Grained Auditing
 Use functions to perform complex checking
— Gives flexibility to policies
CREATE OR REPLACE FUNCTION outside_hours
RETURN BINARY_INTEGER
AS
v_return_val NUMBER;
v_day_of_week VARCHAR2(1) := TO_CHAR(sysdate,'DY');
v_hour NUMBER(2):= TO_NUMBER(TO_CHAR(sysdate, 'HH24'));
BEGIN
IF (v_day_of_week IN ('SAT', 'SUN')
OR v_hour < 8
OR v_hour > 17)
THEN v_return_val := 1;
ELSE v_return_val := 0;
END IF;
RETURN v_return_val;
END;
— Checks if time is outside of working hours
56
Manipulating Auditing Polices
 Auditing occurs on emptab_fga if function outside_hours returns '1'
— Outside of working hours
BEGIN
dbms_fga.drop_policy(
object_schema => 'SCOTT'
,object_name
=> 'EMPTAB_FGA'
,policy_name
=> 'fga_emp');
END;
/
BEGIN
dbms_fga.add_policy(
object_schema
=>
,object_name
=>
,policy_name
=>
,audit_condition =>
END;
/
'SCOTT'
'EMPTAB_FGA'
'fga_emp'
'SECADMIN.OUTSIDE_HOURS = 1');
57
Column Sensitivity
 Any employee is allowed to access other employee's records
— But must not access the sensitive sal column
 This rule needs column sensitivity
— Auditing occurs only if the column is retrieved and the condition is met
— If no condition, auditing happens when the column is retrieved or
manipulated
BEGIN
dbms_fga.add_policy(object_schema
,object_name
,policy_name
,audit_condition
,audit_column
END;
/
=>
=>
=>
=>
=>
'SCOTT'
'EMPTAB_FGA'
'fga_emp'
'ENAME != USER'
'SAL');
58
Options for Column Auditing
 Use audit_column_opts
— Relevant only when there is a list of columns in audit_column
— Governs whether a statement is audited
Value of audit_column_opts
Auditing action
any_columns
the statement is audited if it references
any column specified in the
audit_column parameter
(default value)
all_columns
the statement must reference all
columns listed in audit_column to be
audited
59
Column Sensitive Audit Test
 Which of the following statements will be audited?
1. SELECT AVG(sal) FROM emptab_fga;
2. SELECT sal FROM emptab_fga WHERE ename = 'SCOTT';
3. SELECT empno,job,sal FROM emptab_fga WHERE deptno = 10;
4. SELECT empno,job FROM emptab_fga WHERE deptno = 10;
5. SELECT sal FROM emptab_fga WHERE ename = 'ZULU';
6. SELECT ename FROM emptab_fga WHERE ename = 'SMITH';
7. SELECT ename FROM emptab_fga WHERE sal > 2975;
60
Audited Statements
 Statements 1, 3 and 7
Who: SCOTT
What: SCOTT.EMPTAB_FGA
Where: - sqlplusw.exe
When: Nov-11 16:18
How:
SELECT AVG(sal) FROM emptab_fga
--------------End of audit record-------------Who: SCOTT
What: SCOTT.EMPTAB_FGA
Where: - sqlplusw.exe
When: Nov-11 16:18
How:
SELECT empno,job,sal FROM emptab_fga WHERE deptno = 10
--------------End of audit record-------------Who: SCOTT
What: SCOTT.EMPTAB_FGA
Where: - sqlplusw.exe
When: Nov-11 16:18
How:
SELECT ename FROM emptab_fga WHERE sal > 2975
--------------End of audit record--------------
61
Pushing Audit Information
 Could be a delay before audit records are seen
 Push alerts out to DBAs
— Use an event handler
— No need to query the audit log for information
BEGIN
dbms_fga.add_policy(object_schema
,object_name
,policy_name
,audit_condition
,audit_column
,handler_schema
,handler_module
END;
/
=>
=>
=>
=>
=>
=>
=>
'SCOTT',
'EMPTAB_FGA'
'fga_emp'
'ENAME != USER'
'SAL'
'SECADMIN'
'FGA_ALERT');
62
The Event Handler
CREATE OR REPLACE PROCEDURE fga_alert (pi_sch VARCHAR2
,pi_tab VARCHAR2
,pi_pol VARCHAR2)
AS
msg VARCHAR2(20000);
BEGIN
msg := 'Wake up Carl - the '||pi_tab||' table owned by '||
pi_sch||' has been accessed with this statement :
'||sys_context('userenv','current_sql')||'. The time is : '
||TO_CHAR(SYSDATE, 'Day DD MON, YYYY HH24:MI:SS');
UTL_MAIL.SEND (
sender
=> '[email protected]'
,recipients => '[email protected]'
,subject
=> 'Salaries in the HR.EMPLOYEES
table have been accessed'
,message
=> msg);
END email_alert;
/
63
FGA Summary
 FGA will not see modifications to queries caused by RLS
 FGA does not show the data that the user received
 FGA does not occur when no rows are returned or updated
— Could combine it with standard auditing
 Cannot circumvent any fine-grained auditing arrangements
— Database centric
64
Auditing
Auditing Overview
Application Auditing
Trigger-based Auditing
Auditing the sys User
Standard Auditing
Fine-Grained Auditing
Managing the Audit Trail
Auditing Recommendations
65
Managing Auditing – the aud$ Table
 When AUDIT_TRAIL is set to DB or DB,EXTENDED
— Auditing information is stored in sys.aud$ in the system tablespace
— Maximum size governed by storage parameters for system tablespace
 Periodically remove data from aud$ to free up space and aid searching
— The aud$ (and fga_log$) tables are ABSOLUTELY THE ONLY
dictionary tables on which direct DML can be performed
• Do not insert, update or delete records in any other dictionary table
— Ordinarily, only sys can perform deletes on the aud$ table
 Any delete on the audit trail is itself audited
— Beware sys can TRUNCATE the aud$ table
66
Audit Trail – Manual Management
 If audit trail is full and CREATE SESSION is being audited
— Users cannot connect to the database
— In this case, connect as SYS and make space in the audit trail
DELETE FROM sys.aud$
WHERE ntimestamp# >
TO_TIMESTAMP ('01-JAN-12 08.08.58.427000 PM')
AND ntimestamp# <
TO_TIMESTAMP ('31-MAR-12 10.23.59.681000 PM');
DELETE FROM sys.aud$;
 Shrink or truncate aud$ to regain the space if required
ALTER TABLE sys.aud$ SHRINK SPACE;
TRUNCATE TABLE sys.aud$;
67
Audit Trail Management Settings
SELECT * FROM dba_audit_mgmt_config_params;
PARAMETER_NAME
------------------------DB AUDIT TABLESPACE
DB AUDIT TABLESPACE
AUDIT FILE MAX SIZE
AUDIT FILE MAX SIZE
AUDIT FILE MAX AGE
AUDIT FILE MAX AGE
DB AUDIT CLEAN BATCH SIZE
DB AUDIT CLEAN BATCH SIZE
OS FILE CLEAN BATCH SIZE
OS FILE CLEAN BATCH SIZE
PARAMETER_VALUE
--------------SYSAUX
SYSAUX
10000
10000
5
5
10000
10000
1000
1000
AUDIT_TRAIL
-------------------STANDARD AUDIT TRAIL
FGA AUDIT TRAIL
OS AUDIT TRAIL
XML AUDIT TRAIL
OS AUDIT TRAIL
XML AUDIT TRAIL
STANDARD AUDIT TRAIL
FGA AUDIT TRAIL
OS AUDIT TRAIL
XML AUDIT TRAIL
 Values can be set using dbms_audit_mgmt
— Part of SE and EE from Oracle11gR2
• Previously available only through Audit Vault
68
Audit Trail – Automatic Management
 For the database audit trail, individual audit records created before a
specified timestamp can be purged using dbms_audit_mgmt
 For the operating system audit trail, you purge whole audit files that were
created before the timestamp
— Can take a while to complete
 Preliminary steps :
1. If necessary, tune online and archive redo log sizes
• Deleting the audit trail can generate much redo and undo
• Could move audit trail to sysaux tablespace
– Use dbms_audit_mgmt.set_audit_trail_location
2. Plan a timestamp and archive strategy
• Decide how much audit to keep
3. Initialize the audit trail cleanup operation
• Use dbms_audit_mgmt.init_cleanup
69
Automatic Management using dbms_audit_trail
BEGIN
dbms_audit_mgmt.init_cleanup(
audit_trail_type => dbms_audit_mgmt.audit_trail_fga_std
,default_cleanup_interval => 24);
END;
 FGA audit trail will now be in sysaux
CREATE OR REPLACE PROCEDURE sys.delete_dbfga_records IS
BEGIN
dbms_audit_mgmt.set_last_archive_timestamp(
audit_trail_type => dbms_audit_mgmt.audit_trail_fga_std
,last_archive_time => SYSTIMESTAMP – 1);
dbms_audit_mgmt.clean_audit_trail(
audit_trail_type => dbms_audit_mgmt.audit_trail_fga_std
,use_last_arch_timestamp => TRUE);
END;
 Cleans out FGA audit records earlier than the newly set timestamp
70
Create Job with Schedule to Clean the Audit Trail
 Test routine cleans the audit trail every ten seconds
BEGIN
dbms_scheduler.create_schedule (
schedule_name
=> 'DELETE_DBFGA_RECORDS_SCHED'
,repeat_interval =>'FREQ = SECONDLY; INTERVAL = 10;’);
END;
BEGIN
dbms_scheduler.create_job (
job_name => 'DELETE_DBFGA_RECORDS_JOB'
,job_type => 'STORED_PROCEDURE'
,job_action => 'SYS.DELETE_DBFGA_RECORDS'
,enabled => TRUE
,auto_drop => false
,schedule_name => 'DELETE_DBFGA_RECORDS_SCHED');
END;
71
dbms_audit_mgmt.create_purge_job
 Automates setting up the job for purging (wrapper on dbms_scheduler)
BEGIN
dbms_audit_mgmt.create_purge_job(
audit_trail_type => dbms_audit_mgmt.audit_trail_fga_std
,audit_trail_purge_interval => 1
,audit_trail_purge_name => 'HOURLY_PURGE_FGA'
,use_last_arch_timestamp => TRUE);
END;
— But cannot advance/change the timestamp
• Still need to set up a procedure and job/schedule to do the advance
— Minimum interval is one hour
 See the Oracle Support document
— Known Issues When Using: DBMS_AUDIT_MGMT [ID 804624.1]
72
Automatic
of Audit
Trail
Audit Trail Purging
– Automatic
Management
(continued)
 Optionally, Configure audit trail records to be deleted in batches
BEGIN
dbms_audit_mgmt.set_audit_trail_property(
audit_trail_type => dbms_audit_mgmt.audit_trail_db_std
,audit_trail_property => dbms_audit_mgmt.db_delete_batch_size
,audit_trail_property_value => 100000);
Standard auditing
END;
— audit_trail_type can be set to
• audit_trail_db_std
• audit_trail_db_aud ??
• audit_trail_xml
• audit_trail_all ??
1st purge
Start auditing
2nd purge
audit_trail_fga_std
audit_trail_os
audit_trail_files
3rd purge 4th purge
time
73
Auditing
Auditing Overview
Application Auditing
Trigger-based Auditing
Auditing the sys User
Standard Auditing
Fine-Grained Auditing
Managing the Audit Trail
Auditing Recommendations
74
Auditing Recommendations
 Use system level auditing
 Use FGA where appropriate
 Audit access and change to critical data
 Analyse the audit trail and logs
— Tools can help here
 Create reports
 Create procedures / policies
 Review report contents
 Set alerts
 Act on the contents
75
Auditing Techniques for Oracle
Database 11g
Carl Dudley
University of Wolverhampton, UK
UKOUG Committee
Oracle ACE Director
[email protected]
Carl Dudley – University of Wolverhampton