Download 9.5: Database Security - TFE

Chapter 9
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Explain the necessity for backup.
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Describe backup scope and methods.
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Describe the different RAID (redundant array of independent
disks) levels.
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Explain the need for data storage policies.
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Explain database protections.
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Explain the need for database access controls, auditing, and
encryption.
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Describe the difference between data leakage and data theft.
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Explain data deletion, destruction, and disposal.
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Explain digital rights management (DRM) and how it can
prevent data loss.
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In prior chapters we focused on
◦ Protecting data as it passed over networks (Chapter 3)
◦ Hardening hosts that store data (Chapter 7)
◦ Securing applications that process data (Chapter 8)
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This chapter will emphasize the protection of
stored data
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9.1 Introduction
9.2 Data Protection: Backup
9.3 Backup Media and RAID
9.4 Data Storage Policies
9.5 Database Security
9.6 Data Loss Prevention
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Data are the principal elements of any
information system
Businesses gather enormous amounts of data
◦ Information is then extracted for decision making
◦ Data are valuable assets that are core components
of a larger corporate strategy
◦ Source code, intellectual property, user data, etc.
must all be protected
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This chapter will primarily focus on securing
data while it is being stored
More specifically:
◦
How backup can prevent accidental data loss
◦
How to securely store data in a database
◦
How to prevent data from being taken out of the
corporation
◦
How to securely dispose of data
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9.1 Introduction
9.2 Data Protection: Backup
9.3 Backup Media and RAID
9.4 Data Storage Policies
9.5 Database Security
9.6 Data Loss Prevention
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Image Backup
◦ Everything, including programs and settings
◦ Image backup is very slow
◦ Data files change the most rapidly, so doing several
file/directory data backups for each image backup
may be appropriate
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Shadowing
◦ A backup copy of each file being worked on is
written every few minutes to the hard drive, or to
another location
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Continuous Data Protection (CDP)
◦ Used when a firm has two server locations
◦ Each location backs up the other in real time
◦ Other site can take over very quickly in case of a
disaster, with little data loss
◦ Requires expensive high–speed transmission link
between the sites
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PCs back up one another.
Data is stored redundantly.
Security issues must be addressed.
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9.1 Introduction
9.2 Data Protection: Backup
9.3 Backup Media and RAID
9.4 Data Storage Policies
9.5 Database Security
9.6 Data Loss Prevention
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Data Retention Policies
◦ There are strong legal requirements for how long
certain types of data must be kept
◦ The legal department must get involved in retention
policies
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Auditing Policy Compliance
◦ All policies should be audited
◦ Includes tracing what happened in samples of data
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Benefits of Retention
◦ Major part of corporate memory
◦ Can retrieve old e-mail for current purposes
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Dangers of Retention
◦ Legal discovery process
◦ Defendant must supply relevant e-mails
◦ Potentially very damaging information
◦ Always expensive
◦ Even though very expensive to retrieve, firms must
pay whatever is necessary to do so
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Accidental Retention
◦ Even if firms delete e-mail from mail servers, may
be stored on backup tapes
◦ Users will often store copies on their own
computers
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Message Authentication
◦ Spoofed messages can frame employees or the firm
itself
◦ Need message authentication to prevent spoofed
sender addresses
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User Training
◦ Never put anything in a message that you would not
want seen in court, printed in the newspaper, or
read by your boss
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9.1 Introduction
9.2 Data Protection: Backup
9.3 Backup Media and RAID
9.4 Data Storage Policies
9.5 Database Security
9.6 Data Loss Prevention
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Databases
◦ Often used in mission-critical applications
◦ Require additional security precautions
◦ Relational databases: Tables (relations) with rows
(records) and columns (attributes)
◦ As discussed earlier, avoid SQL injection attacks
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Databases
◦ Restrict Access to Data
 Restrict users to certain columns (attributes) in
each row
 For instance, deny access to salary column to most users
 Limit access control to rows
 For instance, only rows containing data about people in
the user’s own department
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Databases
◦ Restrict granularity (level of detail)
 Prevent access to individual data
 Allow trend analysts to deal only with sums and
averages for aggregates, such as departments
◦ Restrict information about the structure of the
database itself (data model)
 Knowledge about the data model can make SQL
injection much easier
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Database Access Control
◦ Restrict access to databases via database management
systems (e.g., Microsoft SQL Server, MySQL, IBM DB2,
Oracle, etc.)
◦ Rename administrator account, disable guest/public
accounts, lowest possible permissions necessary
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SQL Injection Attacks
◦ Data must be sanitized to remove unacceptable characters
◦ Stored procedures can be used to sanitize and validate
incoming data
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1. Windows
authentication
2. SQL Server
authentication
3. Password
policy options
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Database Auditing
◦ Collect information about users’ interactions with
databases
◦ Policy driven, reflecting legal and regulatory obligations
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What should be audited?
◦ Logins, changes to the database, warnings, exceptions, and
special access
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Trigger - Code that is automatically run when
changes are made to a database
Data Definition Language (DDL) trigger
◦ Used to produce automatic responses if the structure of the
database has been altered (e.g., create new table, drop a
table, alter properties of an existing table)
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Data Manipulation Language (DML) trigger
◦ Used to produce automatic responses if the data has been
altered (e.g., data are inserted, updated, or deleted)
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CREATE TRIGGER EmployeeSalaryChange
ON Employees
FOR UPDATE
AS
DECLARE @EmailBody varchar(1000)
DECLARE @FirstName varchar(20)
DECLARE @LastName varchar(20)
DECLARE @OldSalary int
DECLARE @NewSalary int
IF UPDATE (Salary)
SELECT @FirstName = First_Name,
@LastName = Last_Name,
@OldSalary = Salary
FROM deleted d
SELECT @NewSalary = Salary
FROM inserted
SET @body = 'I just wanted to let you know that @FirstName ' ' @LastName '
changed their salary from' @OldSalary ' to ' @NewSalary
EXEC master..xp_sendmail
@recipients = '[email protected]',
@subject = 'Somebody changed their salary',
@message = @body
GO
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Key Escrow
◦ Loss of the key is disastrous
 Not like losing a password that can be reset
◦ Key escrow stores a copy of the key in a safe place
◦ Bad if managed by user
 May not do it
 May not be able to find it
 If fired, may refuse to give it back, locking up all
data on the computer
◦ Central key escrow on a corporate server is better
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9.1 Introduction
9.2 Data Protection: Backup
9.3 Backup Media and RAID
9.4 Data Storage Policies
9.5 Database Security
9.6 Data Loss Prevention
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Spiders (crawlers) - Navigate the web gathering,
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Web Scraper - Tool that extracts predefined data
organizing, and indexing web content
from specified webpages
 Can aggregate extracted data from multiple websites
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Mashup - Combining data from various sites or
applications
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Data Destruction Is Necessary
◦ Backup media are not needed beyond their
retention dates if…
 a computer is to be discarded
 the computer is to be sold or given to another
user
◦ Drive-wiping software for hard drives
 Reformatting the hard drive is not enough
◦ Shred CDs and DVDs
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
www.ntbugtraq.com

www.securityfocus.com
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www.microsoft.com/technet/treeview/default.asp?url=/technet/secu
rity/current.asp
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www.cert.org
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www.sans.org
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www.incidents.org

www.microsoft.com/security
© 2015 Pearson Education Ltd.
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© 2015 Pearson Education Ltd.