Database Security and Auditing: Protecting Data Integrity and Accessibility

Chapter 8 Application Data Auditing

Objectives • Understand the difference between the auditing architecture of DML Action Auditing Architecture and DML changes • Create and implement Oracle triggers • Create and implement SQL Server triggers • Define and implement Oracle fine-grained auditing Database Security and Auditing 2

Objectives (continued) • Create a DML statement audit trail for Oracle and SQL Server • Generate a data manipulation history • Implement a DML statement auditing using a repository Database Security and Auditing 3

Objectives (continued) • Understand the importance and the implementation of application errors auditing in Oracle • Implement Oracle PL/SQL procedure authorization Database Security and Auditing 4

DML Action Auditing Architecture • Data Manipulation Language (DML): companies use auditing architecture for DML changes • DML changes can be performed on two levels: – Row level – Column level • Fine-grained auditing (FGA) Database Security and Auditing 5

DML Action Auditing Architecture (continued) Database Security and Auditing 6

DML Action Auditing Architecture (continued) Database Security and Auditing 7

Oracle Triggers • Stored PL/SQL procedure executed whenever: – DML operation occurs – Specific database event occurs • Six DML events (trigger timings): INSERT, UPDATE, and DELETE • Purposes: – Audits, controlling invalid data – Implementing business rules, generating values Database Security and Auditing 8

Oracle Triggers (continued) Database Security and Auditing 9

Oracle Triggers (continued) • CREATE TRIGGER • Executed in a specific order: – STATEMENT LEVEL triggers before COLUMN LEVEL triggers – BEFORE triggers before AFTER triggers • USER_TRIGGERS data dictionary view: all triggers created on a table • A table can have unlimited triggers: do not overuse them Database Security and Auditing 10

Oracle Triggers (continued) Database Security and Auditing 11

SQL Server Triggers • CREATE TRIGGER DDL statement: creates a trigger • Trigger condition: – Prevents a trigger from firing – UPDATE() and COLUMNS_UPDATE() functions • Logical tables: – DELETED contains original data – INSERTED contains new data Database Security and Auditing 12

SQL Server Triggers (continued) • Restrictions—Transact-SQL statements not allowed: – ALTER and CREATE DATABASE – DISK INIT and DISK RESIZE – DROP DATABASE and LOAD DATABASE – LOAD LOG – RECONFIGURE – RESTORE DATABASE – RESTORE LOG Database Security and Auditing 13

Implementation of an Historical Model with SQL Server • Create a history table: – Same structure as original table – HISTORY_ID column • Create a trigger: inserts original row into the HISTORY table Database Security and Auditing 14

Fine-grained Auditing (FGA) with Oracle • Oracle provides column-level auditing: Oracle PL/SQL-supplied package DBMS_FGA • DBMS_FGA procedures: – ADD_POLICY – DISABLE_POLICY – DROP_POLICY – ENABLE_POLICY Database Security and Auditing 15

Fine-grained Auditing (FGA) with Oracle (continued) • ADD_POLICY parameters: – OBJECT_SCHEMA – OBJECT_NAME – POLICY_NAME – AUDIT_CONDITION – AUDIT_COLUMN – HANDLER_SCHEMA Database Security and Auditing 16

Fine-grained Auditing (FGA) with Oracle (continued) • ADD_POLICY parameters (continued): – HANDLER_MODULE – ENABLE – STATEMENT_TYPES • DBA_FGA_AUDIT_TRAIL: view the audit trail of the DML activities Database Security and Auditing 17

DML Action Auditing with Oracle • Record data changes on the table: – Name of the person making the change – Date of the change – Time of the change • Before or after value of the columns are not recorded Database Security and Auditing 18

DML Action Auditing with Oracle (continued) Database Security and Auditing 19

DML Action Auditing with Oracle (continued) • Steps: – Use any user other than SYSTEM or SYS; with privileges to create tables, sequences, and triggers – Create the auditing table – Create a sequence object – Create the trigger that will record DML operations – Test your implementation Database Security and Auditing 20

History Auditing Model Implementation Using Oracle • Historical data auditing is simple to implement; main components are TRIGGER objects and TABLE objects • Keeps record of: – Date and time the copy of the record was captured – Type of operation applied to the record Database Security and Auditing 21

History Auditing Model Implementation Using Oracle (continued) • Steps: – Use any user other than SYSTEM or SYS; with privileges to create tables, sequences, and triggers – Create history table – Create the trigger to track changes and record all the values of the columns – Test your implementation Database Security and Auditing 22

DML Auditing Using Repository with Oracle (Simple 1) • Simple Auditing Model 1 • Flag users, tables, or columns for auditing • Requires less database administrative skills: – Application administrators can do it – User interface is built in top of the repository • Auditing flags are flexible • Does not record before or after column values; only registers type of DML operations Database Security and Auditing 23

DML Auditing Using Repository with Oracle (Simple 1) (continued) Database Security and Auditing 24

DML Auditing Using Repository with Oracle (Simple 1) (continued) • Steps: – Use any user other than SYSTEM or SYS – Create triggers – Create sequence object – Build tables to use for applications – Populate application tables Database Security and Auditing 25

DML Auditing Using Repository with Oracle (Simple 1) (continued) • Steps (continued): – Populate auditing repository with metadata – Create the stored package to be used with the trigger – Create triggers for application tables – Test your implementation Database Security and Auditing 26

DML Auditing Using Repository with Oracle (Simple 2) • Simple Auditing Model 2: requires a higher level of expertise in PL/SQL • Stores two types of data: – Audit data: value before or after a DML statement – Audit table: name of the tables to be audited Database Security and Auditing 27

DML Auditing Using Repository with Oracle (Simple 2) (continued) Database Security and Auditing 28

DML Auditing Using Repository with Oracle (Simple 2) (continued) • Steps: – Use any user other than SYSTEM or SYS; with privileges to create tables, and triggers – Create the auditing repository – Establish a foreign key in AUDIT_DATA table referencing AUDIT_TABLE table – Create a sequence object – Create the application schema Database Security and Auditing 29

DML Auditing Using Repository with Oracle (Simple 2) (continued) • Steps (continued): – Add data to tables – A stored PL/SQL package will be used for auditing within the triggers – Create triggers for audited tables – Add auditing metadata – Test your implementation Database Security and Auditing 30

Auditing Application Errors with Oracle • Application errors must be recorded for further analysis • Business requirements mandate to keep an audit trail of all application errors • Materials: – Repository consisting of one table – Methodology for your application Database Security and Auditing 31

Auditing Application Errors with Oracle (continued) • Steps: – Select any user other than SYSTEM or SYS; with privileges to create tables, and procedures – Populate tables – Create the ERROR table – Create a stored package to perform the UPDATE statement – Test your implementation: perform and update using the CREATE package Database Security and Auditing 32

Oracle PL/SQL Procedure Authorization • Oracle PL/SQL stored procedures are the mainstay of implementing business rules • Security modes: – Invoker rights: procedure is executed using security credentials of the caller – Definer rights: procedure is executed using security credentials of the owner Database Security and Auditing 33

Oracle PL/SQL Procedure Authorization (continued) • Steps: – Create a new user – Select a user with CREATE TABLE and PROCEDURE privileges – Populate tables – Create stored procedure to select rows in a table – Grant EXECUTE privileges on new procedure – Log on as the new user and query the table – Execute procedure Database Security and Auditing 34

Summary • Two approaches for DML auditing: – Set up an audit trail for DML activities – Register all column values before or after the DML statement (column-level auditing) • Fine-grained auditing (Oracle) • Triggers: – Stored PL/SQL procedure automatically executed – Oracle has six DML events Database Security and Auditing 35

Summary (continued) • Triggers are executed in order • USER_TRIGGERS data dictionary view: shows all triggers • SQL Server 2000: – CREATE TRIGGER DDL statement – Conditional functions: UPDATE() and COLUMNS_UPDATED() • FGA allows generation of audit trail of DML activities Database Security and Auditing 36

Summary (continued) • FGA is capable of auditing columns or tables; Oracle PL/SQL-supplied package DBMS_FGA • PL/SQL stored procedures security modes: – Invoker rights – Definer rights Database Security and Auditing 37