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Data Protection
Chapter 9
Copyright Pearson Prentice Hall 2013

Explain the necessity for backup.

Describe backup scope and methods.

Describe the different RAID levels.

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.

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
Copyright Pearson Prentice Hall 2013
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 element of any
Information system
Businesses gather enormous amounts of data
◦ Information is then extracted for decision making
◦ Data are a 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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Series of attacks against Sony Corp.
◦ Lost data for 100+ million user accounts
◦ Shut down the PlayStation Network
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Subsequent SQL injection attack
◦ 1 million usernames and passwords stolen
◦ Passwords stored as plaintext
◦ Included names, e-mail addresses, phone numbers,
dates of birth, music coupons, layout of the
database, and maps of Sony’s internal corporate
network
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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
Copyright Pearson Prentice Hall 2013
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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Importance
◦ In an incident, you may lose all data that is not
backed up
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Threats That Are Addressed by Backup
◦ Mechanical hard drive failure or damage in a fire or
flood
◦ Data on lost or stolen computers is not available to
the organization
◦ Malware can reformat the hard drive or do other
data destruction
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Scope of Backup
◦ Fraction of information on the hard drive that is
backed up
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File/Directory Data Backup
◦ Select data files and directories to be backed up
 (Do not forget items on the desktop!)
◦ Not good for programs
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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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Full backups
◦ All files and directories
◦ Slow, so it is typically done weekly
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Incremental Backups
◦ Only records changes since the last backup
◦ Fast, so usually done daily
◦ Do incremental backups until the next full backup
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Restoration Order
◦ Restore the full backup first
◦ Then restore incremental backups in the order
created
◦ (Otherwise, newer files will be overwritten)
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Generations
◦ Save several generations of full backups
◦ Usually do not save incremental backups after the
next full backup
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Local backup on individual PCs difficult to enforce.
Centralized backup provides backup labor and
enforcement.
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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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
Servers Normally Use Magnetic Tape
◦ Slow but inexpensive per bit stored
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Second hard drive on computer
◦ Very fast backup
◦ But lost if computer is stolen or burns in a fire
◦ Backup up on tape occasionally for archival (longterm storage)
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Clients Normally Use Optical disks (DVDs)
◦ Attraction is that almost all users have optical disk
burners
◦ Dual-layer DVDs offer about 8 GB of capacity
 This often is not enough
 User may have to insert additional disks to do
backup
◦ Backup up to a second client PC hard drive; then
occasionally back up onto optical disks
◦ The life of information on optical disks is unknown
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RAID—Redundant Array of Independent Disks
◦ Multiple hard drives within a single system
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Increased reliability and performance
◦ A single hard drive failure won’t necessarily
precipitate data loss
◦ Multiple disks can be written to simultaneously
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RAID Levels—ways of configuring multi-disk
arrays
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Shipping Boxes
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Storing Data
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Striping—writing data simultaneously across
multiple disks
◦ Very fast, but no reliability
◦ One disk failure will cause complete data loss
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Mirroring—creating an exact copy of a disk at
the same time
◦ Data transfer speeds remain nominal
◦ Virtually no data loss, but more costly to buy
additional hard drives
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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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Backup Creation Policies
◦ Understand current system and
future needs
◦ Create policies for different types of data and
computer
◦ What should be backed up, how frequently, how
frequently to test restorations, etc.
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Restoration Policies
◦ Do restoration tests frequently
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Media Storage Location
Policies
◦ Store media at a different site
◦ Store backup media in a fireproof and waterproof
safe until it can be moved offsite
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Encryption Policies
◦ Encrypt backup media before moving them so that
confidential information will not be exposed if the
tape is stolen or lost
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Strongly Access Control Policies for Backup
Media
◦ Checkouts are rare and therefore suspicious
◦ Checking out media can result in their loss and the
damages that come with this loss
◦ The manager of the person requesting the checkout
should approve the checkout
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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
◦ Often need to retrieve old 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 if 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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Legal Archiving Requirements
◦ Many laws require retention
 Securities and Exchange Commission
 Many labor laws
 Involuntary terminations
 Public information about job openings
 Medical problem complaints that may relate to
toxic chemicals
◦ Laws vary in duration of storage requirements
◦ Fines or summary judgments if fail to retain and
produce required e-mails
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U.S. Federal Rules of Civil Procedure
◦ Specify rules for all U.S. federal civil trials
◦ Specifically address electronically stored
information
◦ Initial discovery meeting
 Defendant must be able to specify what
information is available
 Comes shortly after a civil lawsuit begins
 Unless carefully thought through beforehand, will
fail
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U.S. Federal Rules of Civil Procedure
◦ Holds on destruction
 Must be put in place if it is foreseeable that a
lawsuit will soon begin
 Must have strong hold procedures to place holds
on all electronically stored information
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Archiving Policies and Processes
◦ Must have them
◦ Must reflect a firm’s legal environment
◦ Must be drawn up with the firm’s legal department
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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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Spreadsheet Security
◦ Spreadsheets are widely used and the subject of
many compliance regulations
◦ Need for security testing
◦ Spreadsheet vault server to implement controls
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2.
Spreadsheets record each
change for auditing purposes
1.
The vault server stores spreadsheets
and strongly controls access to them.
Authentication
Authorizations
Auditing
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3.
Cryptographic
Protections for
Transmissions
4.
Strong Client
Security
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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)

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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Encryption
◦ Makes data unreadable to
someone who does not have the key
◦ Prevents theft of private or trade secret information
◦ May reduce legal liability if lost or stolen data is
encrypted

What to Encrypt
◦ Files and directories
◦ The entire disk
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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, locking up all data
on the computer
◦ Central key escrow on a corporate server is better
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Strong Login Authentication Is Needed
◦ Encryption is transparent to logged-in users
 Once a user is logged in, he or she can see all
encrypted data
◦ Protect with strong password or biometrics
 Ensure that the password is not lost
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File-Sharing Problems
◦ File sharing may be more difficult because files
usually have to be decrypted before sending them
to another computer
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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 Loss Prevention (DLP)
◦ A set of policies, procedures, and systems
designed to prevent sensitive data from being
released to unauthorized persons
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Data Collection
◦ Most companies collect more data than they can
adequately protect
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Personally Identifiable Information (PII)
◦ Private employee or customer information that
can be used to uniquely identify a person
◦ PII includes: names (full name), personal
identification numbers (SSN), addresses (street or
e-mail), personal characteristics (photo), and
linking information (date of birth)
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Data Masking
◦ Obscuring data such that it cannot identify a
specific person, but remains practically useful
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Spiders (crawlers)—navigate the Web gathering,

Web scraper—tool that extracts predefined data
organizing, and indexing web content
from specified web pages
 Can aggregate extracted data from multiple websites
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Mashup—combining data from various sites or
applications
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Latanya Sweeney, k-anonymity: a model for protecting privacy. International Journal
on Uncertainty, Fuzziness and Knowledge-based Systems, 10 (5), 2002; 557-570.
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Geometry
Information
60°
Zip
code
Equilateral
triangle
60°
X°
X = 60°
If you know the name of the
triangle is “equilateral” and two of
the three angles are 60 °, then you
know the third angle is also 60 °.
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Birth
date
Gender
Person = 87% chance of
being identified
If you know a person’s zip code,
date of birth, and gender, then there
is an 87% chance you can
correctly identify that person.
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
Document Restrictions
◦ Attempt to restrict what users can do to
documents, in order to reduce security threats
◦ Embryonic

Digital Rights Management (DRM)
◦ Prevent unauthorized copying,
printing, etc.
◦ May not be able to see parts
of documents
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Data Extrusion Management
◦ Attempts to prevent restricted
data files from leaving the firm
without permission
◦ Watermark with invisible restriction indicators
 Can be notified if sent via e-mail attachments or
FTP
 If each document is given a different watermark,
can forensically identify the source of a document
leak
◦ Traffic analysis to look for unusually large numbers
of outgoing files sent by a user
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Removable Media Controls
◦ Forbid the attachment of USB RAM drives and other
portable media
◦ Reduces user abilities to make copies

Perspective
◦ Have proven difficult to enforce
◦ Often reduces functionality in uncomfortable ways
◦ Companies have been reluctant to use them
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Social Networking
◦ Do not discuss work on personal blogs
 Don’t talk about new marketing campaigns
 Don’t post negative comments about products
◦ Be cautious about information posted on
professional networks
 Competitors can use employee lists to hire away
key employees
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Data Destruction Is Necessary
◦ Backup media are not needed beyond
their retention dates
 If a computer is to be discarded
 If the computer is to be sold or given to another
user
◦ Drive-wiping software for hard drives
 Reformatting the hard drive is not enough
◦ Shredding for CDs and DVDs
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Publishing as Prentice Hall