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Ch07Databases.pptxSecurity in Computing, Fifth Edition
Chapter 7: Databases
From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
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Objectives for Chapter 7
Basic database terminology and concepts
Security requirements for databases
Implementing access controls in databases
Protecting sensitive data
Data mining and big data
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Database Terms
Database (DB)
Database administrator (DBA)
Database management system (DBMS)
Table
Record
Field/element
Schema
Subschema
Attribute
Relation
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Database: A collection of data and a set of rules that organize the data by specifying certain relationships among the data
Database administrator: Person who defines the rules that organize the data and controls who should have access to what parts of the data
Database management system: The system through which users interact with the database
Record: One related group of data
Field/element: Elementary data items that make up a record (e.g., name, address, city)
Schema: Logical structure of a database
Subschema: The portion of a database a given user has access to
Attribute: A column in a database
Relation: A set of database columns
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Database Terms
DB: A collection of data and a set of rules that organize the data by specifying certain relationships among the data
DBA: Person who defines the rules that organize the data and controls who should have access to what parts of the data
DBMS: The system through which users interact with the database
Table: A collection of records
Record: One related group of data
Field/element: Elementary data items that make up a record (e.g., name, address, city)
Schema: Logical structure of a database
Subschema: The portion of a database a given user has access to
Attribute: A column in a database
Relation: A set of database columns
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
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Database Example
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
A database with three tables
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Database Example
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
A database with three tables
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Schema Example
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
The schema of the database from the previous slide
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Queries
A query is a command that tells the database to retrieve, modify, add, or delete a field or record
The most common database query language is SQL
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
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Example SQL Query
SELECT ZIP=‘43210’
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Where do we find databases?
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
This is a good time to encourage students to think about places databases are commonly used and all the purposes they may be used for. Examples such as banks, large retailers, and law enforcement quickly make clear why all of these requirements are critically important. We’ve already discussed many of the ways these requirements are achieved in previous chapters, but the remainder of this chapter covers special considerations for databases.
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Where do we find databases?
Purpose and Use
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
This is a good time to encourage students to think about places databases are commonly used and all the purposes they may be used for. Examples such as banks, large retailers, and law enforcement quickly make clear why all of these requirements are critically important. We’ve already discussed many of the ways these requirements are achieved in previous chapters, but the remainder of this chapter covers special considerations for databases.
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Where do we find databases?
Purpose and Use
CIA
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
This is a good time to encourage students to think about places databases are commonly used and all the purposes they may be used for. Examples such as banks, large retailers, and law enforcement quickly make clear why all of these requirements are critically important. We’ve already discussed many of the ways these requirements are achieved in previous chapters, but the remainder of this chapter covers special considerations for databases.
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Reliability and Integrity
Reliability: in the context of databases, reliability is the ability to run for long periods without failing
Database integrity: concern that the database as a whole is protected against damage
Element integrity: concern that the value of a specific data element is written or changed only by authorized users
Element accuracy: concern that only correct values are written into the elements of a database
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Two-Phase Update (2PC)
Phase 1: Intent
DBMS does everything it can, other than making changes to the database, to prepare for the update
Collects records, opens files, locks out users, makes calculations
DBMS checks commit flag to the database
Phase 2: Commit
DBS sets commit flag in the database
DBMS completes all write operations
DBMS removes the commit flag
If the DBMS fails during either phase 1 or phase 2, it can be restarted and repeat that phase without causing harm
Register for class example (15 seats, 1 left)
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Solution to the concern that the database system would fail in the middle of an update, leaving the database in a partially updated and inconsistent state.
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Other Database Security Concerns
Error detection and correction codes to protect data integrity
For recovery purposes, a database can maintain a change log, allowing it to repeat changes as necessary when recovering from failure
Databases use locks and atomic operations to maintain consistency
Writes are treated as atomic operations (atomicity = all or nothing)
Records are locked during write so they cannot be read in a partially updated state
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Sensitive Data (Confidentiality)
Inherently sensitive
Passwords, locations of weapons
From a sensitive source
Confidential informant
Declared sensitive
Classified document, name of an anonymous donor
Part of a sensitive attribute or record
Salary attribute in an employment database
Sensitive in relation to previously disclosed information
An encrypted file combined with the password to open it
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Types of Disclosures
Exact data (payroll)
Bounds (protect or present)
Negative result (not 0 or not honors)
Existence
Probable value (management survey)
Direct inference
Inference by arithmetic
Aggregation
Hidden data attributes
File tags
Geotags
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
It is important to understand both the range of possible contents of each attribute and the data available to potential attackers in order to apply the appropriate protection mechanisms.
Keeping records from being dumped out of the database is not sufficient to actually prevent disclosure. There are many ways to deduce the content of a database listed on this slide, and all of them must be considered when protecting sensitive database information. It is important to understand both the range of possible contents of each attribute and the data available to potential attackers in order to apply the appropriate protection mechanisms.
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Preventing Disclosure
Suppress obviously sensitive information – restricts usefulness of database
Keep track of what each user knows based on past queries – expensive and not fool proof
Disguise the data – exact value hard to discern
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Security vs. Precision
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Precise, complete, and consistent responses to queries against sensitive information make it more likely that the sensitive information will be disclosed.
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Suppression Techniques
Limited response suppression
Eliminates certain low-frequency elements from being displayed
Combined results
Ranges, rounding, sums, averages
Random sample
Blocking small sample sizes
Random data perturbation
Randomly add or subtract a small error value to/from actual values
Swapping
Randomly swapping values for individual records while keeping statistical results the same
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Less complex data makes for simpler inference and therefore is more likely to require suppression. The disclosure prevention must be balanced against the database requirements, as the loss of precision and completeness may make the database unusable.
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Data Mining
Data mining uses statistics, machine learning, mathematical models, pattern recognition, and other techniques to discover patterns and relations on large datasets
The size and value of the datasets present an important security and privacy challenge, as the consequences of disclosure are naturally high
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
Data Mining Challenges
Correcting mistakes in data
Preserving privacy
Granular access control
Secure data storage
Transaction logs
Real-time security monitoring
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
These remain open challenges, though some are partially solved or are solved in certain data mining packages. Access control, for instance, can often be performed in a coarse way. Correcting mistakes is a problem because data is often moved to more databases before the original database can be corrected—if the need for correction is ever discovered. Data storage is an issue because data may be collected globally and through cloud providers, where security details are largely unknown to users. As data mining platforms evolve, these features will mature.
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Summary
Database security requirements include:
Physical integrity
Logical integrity
Element integrity
Auditability
Access control
User authentication
Availability
There are many subtle ways for sensitive data to be inadvertently disclosed, and there is no single answer for prevention
Data mining and big data have numerous open security and privacy challenges
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From Security in Computing, Fifth Edition, by Charles P. Pfleeger, et al. (ISBN: 9780134085043). Copyright 2015 by Pearson Education, Inc. All rights reserved.
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