Transcript Formal Technical Reviews

Database Security
and Authorization
Sameh Elghzali, CPIM, PMP
EECS710 - Information Security and
Assurance - Fall 2010
1
Outline (1/3)
•
•
Quick database introduction
Database Security and Authorization




•
Database Security Issues
Control Measures
Database Security and DBA
Access Protection, User Accounts, and Database Audits
Discretionary Access Control





Types of Discretionary Privileges
Specifying Privileges Using Views
Revoking Privileges
Propagation of Privileges Using the GRANT OPTION
Specifying Limits on Propagation of Privileges
2
Outline (2/3)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
3
Outline (3/3)
•
•
•
•
•
Privacy Issues and Preservation
Database Survivability
Oracle’s EnterpriseOne DB Security Features
Summary
References
4
Quick Database Introduction (1/5)
Figure 1
A simplified database
system environment
5
Quick Database Introduction (2/5)
• There are multiple architecture
Centralized
Client-Server
Figure 2
Logical two tier
Client/server
Architecture.
6
Quick Database Introduction (3/5)
•
Relational Database Elements
 Schema
 Relation
/ Table / File
 Tuple / Row / Record
 Attribute / Column / Field
 Primary key

Uniquely identifies a row
 Foreign

key
Links one table to attributes in another
 View
/ Virtual table
7
Quick Database Introduction (4/5)
Figure 3
8
Quick Database Introduction (5/5)
•
Typical DBMS Functionality








Define a database (data types, structures, constraints)
Construct or Load the initial database contents
Manipulating the database (Retrieval, Modification)
Processing and Sharing by a set of concurrent users and application
programs
Protection or Security measures to prevent unauthorized access
“Active” processing to take internal actions on data
Presentation and Visualization of data
Maintaining the database and associated programs over the lifetime of
the database application
9
Quick Database Introduction (5/5)
Figure 3
A database that stores
student and course
Information.
10
Outline (1/2)
•
•
Quick database introduction
Database Security and Authorization




•
Database Security Issues
Control Measures
Database Security and DBA
Access Protection, User Accounts, and Database Audits
Discretionary Access Control





Types of Discretionary Privileges
Specifying Privileges Using Views
Revoking Privileges
Propagation of Privileges Using the GRANT OPTION
Specifying Limits on Propagation of Privileges
11
Database Security Issues (1/9)
•
Types of Security
 Legal
and ethical issues
Legal rights to access certain information
 Numerous laws governing private information

 Policy

issues
What kind of information should not be made publicly
available? (examples: credit ratings and medical records)
 System-related

Which level various security functions should be enforce
 The

issues
need to identify multiple security levels
Categorize data and users based on their classifications
12
Database Security Issues (2/9)
•
Threats to databases

Loss of integrity


Loss of availability


Protection from improper modification
Availability refers to making object available to human and
program where they have a legitimate right
Loss of confidentiality
Confidentiality refers to the protection of data from unauthorized
disclosure
 Can range from violations to Data Privacy Act to the
jeopardization of national security
 Could result in loss of public confidence, embarrassment, or legal
action against the organization

13
Database Security Issues (3/9)
•
Four kinds of countermeasures can be implemented:
Access control
 Inference control
 Flow control
 Encryption

14
Database Security Issues (4/9)
A DBMS includes a database security and
authorization subsystem that is responsible for
ensuring the security portions of a database
against unauthorized access
• Two types of database security mechanisms:
•
 Discretionary

Grant privileges to users to access data in a specified mode
 Mandatory

security mechanisms
security mechanisms
Used to enforce multilevel security by classifying data and
users into various security classes or levels and then
implement the appropriate security policy
15
Database Security Issues (5/9)

Role-bases security is an extension of mandatory access
control, which enforce policies and privileges on the concept
of roles
Figure 4 Multiple Access Control Policies
DAC, MAC and RBAC are not mutually exclusive.
A system may implement two or even three of these policies for
some or all types of access.
Source: [SAND94]
16
Database Security Issues (6/9)
•
The security mechanism of a DBMS must include
provisions for restricting access to the database
system as a whole either to obtain information
or make malicious changes to database
 This
function is called access control and is handled
by creating user accounts and passwords to control
login process by the DBMS
17
Database Security Issues (7/9)
•
The security problem associated with databases
is that of controlling the access to a statistical
database, which is used to provide statistical
information or summaries of values based on
various criteria
•
Countermeasure can be implemented
 inference
control measures
18
Database Security Issues (8/9)
Another security issue is that of flow control,
which prevents information from flowing in
such a way that it reaches unauthorized users
• Channels that are pathways for information to
flow implicitly in ways that violate the security
policy of an organization are called covert
channels
• Countermeasure can be implemented
•

Allow all flows of information except from class
confidential (C) to class nonconfidential (N)
19
Database Security Issues (9/9)
A final security issue is data encryption, which
is used to protect sensitive data (such as credit
card numbers, SSN) that is being transmitted
via some type communication network
• The data is encoded using some encoding
algorithm in such way that
•
 An
unauthorized user who access encoded data will
have difficulty deciphering it
 An authorized users are given decoding or decrypting
algorithms (or keys) to decipher data
20
Outline (1/2)
•
•
Quick database introduction
Database Security and Authorization




•
Database Security Issues
Control Measures
Database Security and DBA
Access Protection, User Accounts, and Database Audits
Discretionary Access Control





Types of Discretionary Privileges
Specifying Privileges Using Views
Revoking Privileges
Propagation of Privileges Using the GRANT OPTION
Specifying Limits on Propagation of Privileges
21
Control Measures (1/2)
Must include provisions for restricting access for
the database system as a whole
• Must prevent access to detailed confidential
information about specific individuals in
Statistical databases
• Must prevent information from flowing in such
way that it reaches to unauthorized users
through what is called covert channels
• Must protect sensitive data that is transmitted
via some type of communications network
•
22
Control Measures (2/2)
•
There are four control measures that are used
to provide security of data in databases
 Access
control
 Inference control
 Flow control
 Data encryption
23
Outline (1/2)
•
•
Quick database introduction
Database Security and Authorization




•
Database Security Issues
Control Measures
Database Security and DBA
Access Protection, User Accounts, and Database Audits
Discretionary Access Control





Types of Discretionary Privileges
Specifying Privileges Using Views
Revoking Privileges
Propagation of Privileges Using the GRANT OPTION
Specifying Limits on Propagation of Privileges
24
Database Security and the DBA (1/2)
•
The database administrator (DBA) is the central
authority for managing a database system
 The
DBA’s responsibilities include
granting privileges to users who need to use the system
 classifying users and data in accordance with the policy of
the organization

•
The DBA is responsible for the overall security
of the database system
25
Database Security and the DBA (2/2)
•
The DBA has a DBA account in the DBMS
Sometimes these are called a system or super user
account
 These accounts provide powerful capabilities such as:

1. Account creation
 2. Privilege granting
 3. Privilege revocation
 4. Security level assignment


Action 1 is access control, whereas 2 and 3 are
discretionary and 4 is used to control mandatory
authorization
26
Outline (1/2)
•
•
Quick database introduction
Database Security and Authorization




•
Database Security Issues
Control Measures
Database Security and DBA
Access Protection, User Accounts, and Database Audits
Discretionary Access Control





Types of Discretionary Privileges
Specifying Privileges Using Views
Revoking Privileges
Propagation of Privileges Using the GRANT OPTION
Specifying Limits on Propagation of Privileges
27
Access Protection, User Accounts,
and Database Audits(1/5)
DBMS provide access control for database for
authenticated users
• DBMS provides specific access rights to portions
of the database
•
 e.g.
create, insert, delete, read, write
 to entire database, tables, selected rows or columns
 possibly dependent on contents of a table entry
28
Access Protection, User Accounts,
and Database Audits(2/5)
•
can support a range of policies:
 centralized
administration
A
small number of privileged users may grant or revoke
access rights
 ownership-based
administration
 The
owner (creator) of a table may grant or revoke access
rights of table
 decentralized
administration
 The
owner of table may grant or revoke authorization rights
to other users, allowing them to grant and revoke access to
the table
29
Access Protection, User Accounts,
and Database Audits(3/5)
•
Whenever a person or group of persons need to
access a database system, the individual or
group must first apply for a user account
 The
DBA will then create a new account id and
password for the user if he/she deems there is a
legitimate need to access the database
•
The user must log in to the DBMS by entering
account id and password whenever database
access is needed
30
Access Protection, User Accounts,
and Database Audits(4/5)
•
The database system must also keep track of
all operations on the database that are applied
by a certain user throughout each login session
 To
keep a record of all updates applied to the
database and of the particular user who applied
each update, we can modify system log, which
includes an entry for each operation applied to the
database that may be required for recovery from a
transaction failure or system crash
31
Access Protection, User Accounts,
and Database Audits(5/5)
•
If any tampering with the database is
suspected, a database audit is performed
A
database audit consists of reviewing the log to
examine all accesses and operations applied to the
database during a certain time period
•
A database log that is used mainly for security
purposes is sometimes called an audit trail
32
Outline (1/2)
•
•
Quick database introduction
Database Security and Authorization




•
Database Security Issues
Types of Security
Database Security and DBA
Access Protection, User Accounts, and Database Audits
Discretionary Access Control





Types of Discretionary Privileges
Specifying Privileges Using Views
Revoking Privileges
Propagation of Privileges Using the GRANT OPTION
Specifying Limits on Propagation of Privileges
33
Discretionary Access Control Based
on Granting and Revoking Privileges
•
The typical method of enforcing discretionary
access control in a database system is based on
the granting and revoking privileges
 Many
current relational DBMS use some variation of
this technique
 The main idea to include statements in the query
language that allow DBA and selected users to grant
and revoke privileges
34
Types of Discretionary Privileges
(1/6)
•
The account level:
 At
this level, the DBA specifies the particular
privileges that each account holds independently of
the relations in the database
•
The relation level (or table level):
 At
this level, the DBA can control the privilege to
access each individual relation or view in the
database
35
Types of Discretionary Privileges
(2/6)
•
The privileges at the account level apply to the
capabilities provided to the account itself and can
include






the CREATE SCHEMA or CREATE TABLE privilege, to
create a schema or base relation;
the CREATE VIEW privilege;
the ALTER privilege, to apply schema changes such
adding or removing attributes from relations;
the DROP privilege, to delete relations or views;
the MODIFY privilege, to insert, delete, or update tuples;
and the SELECT privilege, to retrieve information from
the database by using a SELECT query
36
Types of Discretionary Privileges
(3/6)
•
The second level of privileges applies to the relation
level

•
This includes base relations and virtual (view) relations
The granting and revoking of privileges generally follow
an authorization model for discretionary privileges
known as the access matrix model where
The rows of a matrix M represents subjects (users,
accounts, programs)
 The columns represent objects (relations, records,
columns, views, operations)
 Each position M(i,j) in the matrix represents the types of
privileges (read, write, update) that subject i holds on
object j

37
Types of Discretionary Privileges
(4/6)
•
To control the granting and revoking of relation
privileges, each relation R in a database is assigned an
owner account, which is typically the account that was
used when the relation was created in the first place
The owner of a relation is given all privileges on that
relation
 DBA can assign an owner to a whole schema by creating
the schema and associating the appropriate authorization
identifier with that schema, using the CREATE SCHEMA
command
 The owner account holder can pass privileges on any of
the owned relation to other users by granting privileges
to their accounts

38
Types of Discretionary Privileges
(5/6)
•
In SQL the following types of privileges can be granted
on each individual relation R:

SELECT (retrieval or read) privilege on R:
Gives the account retrieval privilege
 Gives the account the privilege to use the SELECT
statement to retrieve tuples from R


MODIFY privileges on R:
Gives the account the capability to modify tuples of R
 This privilege is further divided into UPDATE, DELETE, and
INSERT privileges to apply the corresponding SQL command
to R
 In addition, both the INSERT and UPDATE privileges can
specify that only certain attributes can be updated by the
account

39
Types of Discretionary Privileges
(6/6)
•
The following types of privileges in SQL can be
granted on each individual relation R:
 REFERENCES privilege on R:
 This gives the account the capability to reference relation
R when specifying integrity constraints
 The privilege can also be restricted to specific attributes of
R
•
Please notice that to create a view, the
account must have SELECT privilege on all
relations involved in the view definition
40
Specifying Privileges Using Views
•
The mechanism of views is an important discretionary
authorization mechanism in its own right. For example,
If the owner A of a relation R wants another account B to
be able to retrieve only some fields of R, then A can
create a view V of R that includes only those attributes
and then grant SELECT on V to B
 The same applies to limiting B to retrieving only certain
tuples of R; a view V’ can be created by defining the view
by means of a query that selects only those tuples from R
that A wants to allow B to access

41
Revoking Privileges
•
In some cases it is deemed necessary to grant a
privilege to a user only temporarily to make
good control of security and access rights. For
example,
 The
owner of a relation may want to grant the
SELECT privilege to a user for a specific task and
then revoke that privilege once the task is
completed.
 Hence, a mechanism for revoking privileges is
necessary. In SQL, a REVOKE command is included
for the purpose of canceling privileges.
42
Propagation of Privileges using the
GRANT OPTION
•
•
Whenever the owner A of a relation R grants a privilege
on R to another account B, privilege can be given to B
with or without the GRANT OPTION
If the GRANT OPTION is given, this means that B can
also grant that privilege on R to other accounts
Suppose that B is given the GRANT OPTION by A and that
B then grants the privilege on R to a third account C, also
with GRANT OPTION. In this way, privileges on R can
propagate to other accounts without the knowledge of
the owner of R
 If the owner account A now revokes the privilege granted
to B, all the privileges that B propagated based on that
privilege should automatically be revoked by the system

43
Specifying Limits on Propagation of
Privileges
•
Techniques to limit the propagation of
privileges have been developed, although they
have not yet been implemented in most DBMSs
and are not a part of SQL
 Limiting
horizontal propagation to an integer
number i means that an account B given the GRANT
OPTION can grant the privilege to at most i other
accounts
 Vertical propagation is more complicated; it limits
the depth of the granting of privileges
44
An Example(1/8)
•
Suppose that the DBA creates four accounts

A1, A2, A3, A4, A5
•
and wants only A1 to be able to create base relations
Then the DBA must issue the following GRANT command
in SQL
GRANT CREATETAB TO A1;
•
The same effect can be accomplished by DBA issuing a
CREATE SCHEMA command as follows:
CREATE SCHEMA EXAMPESCHEMA
AUTHORIZATION A1;
45
An Example(2/8)
•
•
User account A1 can create tables under the schema
called EXAMPESCHEMA
Suppose that A1 creates the two base relations
EMPLOYEE and DEPARTMENT

•
A1 is then owner of these two relations and hence all the
relation privileges on each of them
Suppose that A1 wants to grant A2 the privilege to
insert and delete tuples in both of these relations, but
A1 does not want A2 to be able to propagate these
privileges to additional accounts:
GRANT INSERT, DELETE ON
EMPLOYEE, DEPARTMENT TO A2;
46
An Example(3/8)
•
Suppose that A1 wants to grant A5 the privilege to
insert and delete tuples in both of these relations, and
A1 wants A5 to be able to propagate these privileges to
additional accounts:
GRANT INSERT, DELETE ON EMPLOYEE,
DEPARTMENT TO A5 WITH GRANT OPTION;
•
A5 then can propagate the acquired privileges
to others
47
An Example(4/8)
Figure 5
48
An Example(5/8)
•
•
Suppose that A1 wants to allow A3 to retrieve
information from either of the two tables and also to
be able to propagate the SELECT privilege to other
accounts
A1 can issue the command:
GRANT SELECT ON EMPLOYEE, DEPARTMENT
TO A3 WITH GRANT OPTION;
•
A3 can grant the SELECT privilege on the EMPLOYEE
relation to A4 by issuing:
GRANT SELECT ON EMPLOYEE TO A4;

Please notice that A4 can’t propagate the SELECT
privilege because GRANT OPTION was not given to A4
49
An Example(6/8)
•
Suppose that A1 decides to revoke the SELECT
privilege on the EMPLOYEE relation from A3; A1
can issue:
REVOKE SELECT ON EMPLOYEE FROM A3;
•
The DBMS must now automatically revoke the
SELECT privilege on EMPLOYEE from A4, too,
because A3 granted that privilege to A4 and A3
does not have the privilege any more
50
An Example(7/8)
•
•
Suppose that A1 wants to give back to A3 a limited capability to
SELECT from the EMPLOYEE relation and wants to allow A3 to be
able to propagate the privilege
 The limitation is to retrieve only the NAME, BDATE, and
ADDRESS attributes and only for the tuples with DNO=5
A1 then create the view:
CREATE VIEW A3EMPLOYEE AS
SELECT NAME, BDATE, ADDRESS
FROM EMPLOYEE
WHERE DNO = 5;
•
After the view is created, A1 can grant SELECT on the view
A3EMPLOYEE to A3 as follows:
GRANT SELECT ON A3EMPLOYEE TO A3
WITH GRANT OPTION;
51
An Example(8/8)
•
•
Finally, suppose that A1 wants to allow A4 to update
only the SALARY attribute of EMPLOYEE;
A1 can issue:
GRANT UPDATE ON EMPLOYEE (SALARY) TO
A4;
The UPDATE or INSERT privilege can specify particular
attributes that may be updated or inserted in a relation
 Other privileges (SELECT, DELETE) are not attribute
specific

52
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
53
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(1/8)
•
•
The discretionary access control techniques of granting
and revoking privileges on relations has traditionally
been the main security mechanism for relational
database systems
This is an all-or-nothing method:
–
•
A user either has or does not have a certain privilege
In many applications, and additional security policy is
needed that classifies data and users based on security
classes
–
This approach as mandatory access control, would
typically be combined with the discretionary access
control mechanisms
54
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(2/8)
•
Typical security classes are top secret (TS), secret (S),
confidential (C), and unclassified (U), where TS is the
highest level and U the lowest: TS ≥ S ≥ C ≥ U
•
The commonly used model for multilevel security,
known as the Bell-LaPadula model, classifies each
subject (user, account, program) and object (relation,
tuple, column, view, operation) into one of the security
classifications, T, S, C, or U:

Clearance (classification) of a subject S as class(S) and to
the classification of an object O as class(O)
55
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(3/8)
•
Two restrictions are enforced on data access
based on the subject/object classifications:
 Simple
security property: A subject S is not allowed
read access to an object O unless class(S) ≥ class(O)
 A subject S is not allowed to append/write an object
O unless class(S) ≤ class(O). This known as the star
property (or * property)

•
*-property:(S, O, append) has class(S) ≤class(O) and (S, O,
write) has class(S) = class(O)
Third restriction are enforced on data access
bases on discretionary security
56
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(4/8)
•
•
•
•
•
To incorporate multilevel security notions into the relational
database model, it is common to consider attribute values and
tuples as data objects
Hence, each attribute A is associated with a classification
attribute C in the schema, and each attribute value in a tuple is
associated with a corresponding security classification
In addition, in some models, a tuple classification attribute TC is
added to the relation attributes to provide a classification for each
tuple as a whole
Hence, a multilevel relation schema R with n attributes would be
represented as
 R(A1,C1,A2,C2, …, An,Cn,TC)
 TCt = Max(C1t, …… , Cnt)
where each Ci represents the classification attribute associated
with attribute Ai
57
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(5/8)
•
The value of the TC attribute in each tuple t –
which is the highest of all attribute
classification values within t
 TC
provides a general classification for the tuple
itself
 Ci provides a finer security classification for each
attribute value within the tuple
 The apparent key of a multilevel relation is the set
of attributes that would have formed the primary
key in a regular(single-level) relation
58
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(6/8)
•
A multilevel relation will appear to contain different
data to subjects (users) with different clearance levels
In some cases, it is possible to store a single tuple in the
relation at a higher classification level and produce the
corresponding tuples at a lower-level classification
through a process known as filtering
 In other cases, it is necessary to store two or more tuples
at different classification levels with the same value for
the apparent key

•
This leads to the concept of polyinstantiation where
several tuples can have the same apparent key value
but have different attribute values for users at
different classification levels
59
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(7/8)
The entity integrity rule for multilevel
relations states that all attributes that are
members of the apparent key must not be null
and must have the same security classification
within each individual tuple
• All other attribute values in the tuple must
have a security classification greater than or
equal to that of the apparent key
•
–
This constraint ensures that a user can see the key
if the user is permitted to see any part of the tuple
at all
60
Mandatory Access Control and Role-Based
Access Control for Multilevel Security(8/8)
•
Null and interinstance integrity rules
informally ensure that if a tuple value at some
security level can be filtered (derived) from a
higher-classified tuple, then it is sufficient to
store the higher-classified tuple in the
multilevel relation
61
An Example
a) EMPLOYEE
Name
Smith U
Brown C
Salary
40000 C
80000 S
JobPerformance
Fair S
Good C
TC
S
S
Salary
40000 C
NULL C
JobPerformance
NULL C
Good C
TC
C
C
Salary
NULL U
JobPerformance
NULL U
TC
U
Salary
40000 C
40000 C
80000 S
JobPerformance
Fair S
Excellent C
Good C
TC
S
C
S
b) EMPLOYEE
Name
Smith U
Brown C
c) EMPLOYEE
Name
Smith U
d) EMPLOYEE
Name
Smith U
Smith C
Brown C
62
Figure 6
A multilevel relation to
illustrate a multilevel
security. (a) The original
EMPLOYEE tuples. (b)
Appearance of EMPLOYEE after
filtering of classification
C users. (c) Appearance of
EMPLOYEE after filtering for
classification U users. (d)
Polyinstantiation of the
Smith tuple.
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
63
Comparing Discretionary Access Control and
Mandatory Access Control (1/2)
•
Discretionary Access Control (DAC) policies
are characterized by a high degree of
flexibility, which makes them suitable for a
large variety of application domains
 The
main drawback of DAC models is their
vulnerability to malicious attacks, such as Trojan
horses embedded in application programs
 DAC does not impose any control on how information
is propagated and used once it has been accessed by
users authorized to do so
64
Comparing Discretionary Access Control and
Mandatory Access Control(2/2)
•
Mandatory access control (MAC) policies ensure
a high degree of protection
 MAC
prevents any illegal flow of information
MAC has the drawback of being too rigid and
they are only applicable in limited
environments
• Discretionary policies are preferred in many
cases because they offer a better trade-off
between security and applicability
•
65
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
66
Role-Based Access Control(1/4)
•
Role-based access control (RBAC) emerged rapidly in
the 1990s

•
•
a proven technology for managing and enforcing security in
large-scale enterprise wide systems
Its basic notion is that permissions are associated with
roles then users are assigned to appropriate roles
Roles can be created using the CREATE ROLE and
DESTROY ROLE commands

The GRANT and REVOKE commands discussed under DAC
can then be used to assign and revoke privileges from
roles
67
Role-Based Access Control(2/4)
•
RBAC appears to be a viable alternative to
traditional discretionary and mandatory access
controls
 RBAC
ensures that only authorized users are given
access to certain data or resources
Many DBMSs have allowed the concept of roles,
where privileges can be assigned to roles
• Role hierarchy in RBAC is a natural way of
organizing roles to reflect the organization’s
lines of authority and responsibility
•
68
Role-Based Access Control(3/4)
•
Another important consideration in RBAC
systems is the possible temporal constraints
that may exist on roles, such as
 time
and duration of role activations
 timed triggering of a role by an activation of
another role
•
Using an RBAC model is highly desirable goal
for addressing the key security requirements of
Web-based applications
69
Role-Based Access Control(4/4)
In contrast, DAC and MAC models lack
capabilities needed to support the security
requirements emerging enterprises and Webbased applications
• RBAC becomes a superset model that can run,
mimic the behavior of DAC and MAC
• RBAC works well for DBMS
•
 Eases
admin burden, improves security
 Addresses the security issues related to the
execution of tasks and workflows
70
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
71
Access Control Policies for
E-Commerce and the Web(1/2)
•
E-Commerce environments require elaborate
policies that go beyond traditional DBMSs
 In
an e-commerce environment the resources to be
protected are not only traditional data but also
knowledge and experience
 The access control mechanism should be flexible
enough to support a wide spectrum of
heterogeneous protection objects
•
A related requirement is the support for
content-based access-control
72
Access Control Policies for
E-Commerce and the Web(2/2)
•
Another requirement is related to the heterogeneity of
subjects, which requires access control policies based
on user characteristics and qualifications
A possible solution, to better take into account user
profiles in the formulation of access control policies, is to
support the notion of credentials
 A credential is a set of properties concerning a user that
are relevant for security purposes



For example, age, position within an organization
It is believed that the XML language can play a key role in
access control for e-commerce applications
73
XML Access Control
•
Efforts are underway to develop security
standards
 Digital
signature and encryption for XML
 Can support signing some parts of the XML tree
rather than the complete document
 XML encryption applies to parts of documents and to
documents in persistent storage
74
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
75
Introduction to Statistical
Database Security(1/6)
Statistical databases are used mainly to
produce statistics on various populations
• The database may contain confidential data on
individuals, which should be protected from
user access
• Users are permitted to retrieve statistical
information on the populations, such as
averages, sums, counts, maximums,
minimums, and standard deviations
•
76
Introduction to Statistical
Database Security(2/6)
A population is a set of tuples of a relation
(table) that satisfy some selection condition
• Statistical queries involve applying statistical
functions to a population of tuples
•
•
For example, we may want to retrieve the number of
individuals in a population or the average income in
the population

However, statistical users are not allowed to retrieve
individual data, such as the income of a specific person
77
Introduction to Statistical
Database Security(3/6)
•
•
Statistical database security techniques must prohibit
the retrieval of individual data
This can be achieved by prohibiting queries that
retrieve attribute values and by allowing only queries
that involve statistical aggregate functions such as
COUNT, SUM, MIN, MAX, AVERAGE, and STANDARD
DEVIATION

Such queries are sometimes called statistical queries
78
Introduction to Statistical
Database Security(4/6)
It is DBMS’s responsibility to ensure confidentiality of
information about individuals, while still providing
useful statistical summaries of data about those
individuals to users. Provision of privacy protection of
users in a statistical database is paramount
• In some cases it is possible to infer the values of
individual tuples from a sequence statistical queries
•

This is particularly true when the conditions result in a
population consisting of a small number of tuples
79
Introduction to Statistical
Database Security(5/6)
Inference counter measures include
• inference detection at database design
 alter
•
database structure or access controls
Runtime inference detection and prevention
 No
statistical queries are permitted whenever the
number of tuples in population falls below some
threshold
 Prohibit sequence of queries that refer repeatedly to
the same population of tuples
•
Inference detection algorithm
80
Introduction to Statistical
Database Security(6/6)
•
add slight inaccuracies or noise to statistics
generated from data
 will
•
result in differences in statistics
Partitioning of the database
 Reject
•
data perturbation techniques
 data
•
queries to subset of data
swapping
output perturbation techniques
 random-sample
•
query
must minimize loss of accuracy in results
81
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
82
Flow Control
•
•
Flow control regulates the distribution or flow of
information among accessible objects
A flow between object X and object Y occurs when a
program reads values from X and writes values into Y

•
Flow controls check that information contained in some
objects does not flow explicitly or implicitly into less
protected objects
A flow policy specifies the channels along which
information is allowed to move

The simplest flow policy specifies just two classes of
information:


confidential (C) and non-confidential (N)
and allows all flows except those from class C to class N
83
Covert Channels(1/2)
•
A covert channel allows a transfer of
information that violates the security or the
policy
•
A covert channel allows information to pass
from a higher classification level to a lower
classification level through improper means
84
Covert Channels(2/2)
•
Covert channels can be classified into two broad
categories:
Storage channels do not require any temporal
synchronization, in that information is conveyed by
accessing system information or what is otherwise
inaccessible to the user
 Timing channel allow the information to be conveyed by
the timing of events or processes

•
Some security experts believe that one way to avoid
covert channels is for programmers to not actually gain
access to sensitive data that a program is supposed to
process after the program has been put into operation
85
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
86
Encryption and Public Key
Infrastructures
Encryption is a mean of maintaining secure
data in an insecure environment
• Encryption consists of applying an encryption
algorithm to data using some pre-specified
encryption key
• The resulting data has to be decrypted using a
decryption key to recover the original data
•
87
The Data and Advanced Encryption
Standards(1/3)
•
The Data Encryption Standard (DES) is a
system developed by the U.S. government in
1976 for use by the general public
 It
has been widely accepted as a cryptographic
standard both in the United States and abroad
•
DES can provide end-to-end encryption on the
channel between the sender A and receiver B
88
The Data and Advanced Encryption
Standards(2/3)
•
DES algorithm is a careful and complex
combination of two of the fundamental building
blocks of encryption:
 substitution
•
and permutation (transposition)
The DES algorithm derives its strength from
repeated application of these two techniques
for a total of 16 cycles
 Plaintext
(the original form of the message) is
encrypted as blocks of 64 bits
 Only 56 of these are actually used by the algorithm
89
The Data and Advanced Encryption
Standards(3/3)
•
After questioning the adequacy of DES, the
National Institute of Standards (NIST)
introduced the Advanced Encryption Standards
(AES)
 This
algorithm has a block size of 128 bits and thus
takes longer time to crack
•
AES-192 and AES-256
•
Key sizes of 192 and 256 bits respectively
90
Outline (2/2)
•
Mandatory Access Control and Role-Based Access
Control for Multilevel Security
Comparing Discretionary Access Control and Mandatory
Access Control
 Role-Based Access Control
 Access Control Policies for E-Commerce and the Web

•
•
Statistical Database Security
Flow Control

•
Covert Channels
Encryption and Public Key Infrastructures



The Data and Advanced Encryption Standards
Public Key Encryption
Digital Signatures
91
Public Key Encryption(1/8)
•
•
Diffie and Hellman In 1976 proposed a new kind of
cryptosystem, which they called public key encryption
Public key algorithms are based on mathematical
functions rather than operations on bit patterns

They involve the use of two separate keys


Conventional encryption uses only one key
The use of two keys can have profound consequences in
the areas of confidentiality, key distribution, and
authentication
92
Public Key Encryption(2/8)
•
The two keys used for public key encryption are
referred to as the public key and the private
key
 the
private key is kept secret, but it is referred to
as private key rather than a secret key (to avoid
confusion with conventional encryption)
 The public key of the pair is made public for others
to use
93
Public Key Encryption(3/8)
•
A public key encryption scheme, or infrastructure, has
six ingredients:
1. Plaintext: This is the data or readable message that is
fed into the algorithm as input
 2. Encryption algorithm: The encryption algorithm
performs various transformations on the plaintext
 3 & 4 Public and private keys: These are pair of keys
that have been selected so that if one is used for
encryption, the other is used for decryption

 The
exec transformations performed by the encryption
algorithm depend on the public or private key that is
provided as input
94
Public Key Encryption(4/8)
 5.
Ciphertext:
This is the scrambled message produced as output. It
depends on the plaintext and the key
 For a given message, two different keys will produce two
different ciphertexts

 6.

Decryption algorithm:
This algorithm accepts the ciphertext and the matching key
and produces the original plaintext
95
Public Key Encryption(5/8)
Public key is made for public and private key is
known only by owner
• A general-purpose public key cryptographic
algorithm relies on
•
 one
key for encryption and
 a different but related key for decryption
96
Public Key Encryption(6/8)
•
The essential steps are as follows:
Each user generates a pair of keys to be used for the
encryption and decryption of messages
 Each user places one of the two keys in a public register
or other accessible file. This is the public key. The
companion key is kept private (private key)
 If a sender wishes to send a private message to a
receiver, the sender encrypts the message using the
receiver’s public key
 When the receiver receives the message, he or she
decrypts it using the receiver’s private key

 No
other recipient can decrypt the message because only
the receiver knows his or her private key
97
Public Key Encryption(7/8)
•
The RSA Public Key Encryption algorithm, one
of the first public key schemes was introduced
in 1978 by Ron Rivest (R), Adi Shamir (S), and
Len Adleman (A) at MIT and is named after
them
 The
RSA encryption algorithm incorporates results
from number theory, such as the difficulty of
determining the large prime factors of a large
number
•
The RSA algorithm also operates with modular
arithmetic – mod n, where n is the product of
two large prime numbers
98
Public Key Encryption(8/8)
•
Two keys, d and e, are used for decryption and encryption
 An important property is that d and e can be interchanged
 n is chosen as a large integer that is a product of two large
distinct prime numbers, a and b
 The encryption key e is a randomly chosen number between 1
and n that is relatively prime to (a-1) x (b-1)
 The plaintext block P is encrypted as Pe mod n
 Because the exponentiation is performed mod n, factoring Pe
to uncover the encrypted plaintext is difficult
 However, the decryption key d is carefully chosen so that
(Pe)d mod n = P
 The decryption key d can be computed from the condition that
d x e= 1 mod ((a-1)x(b-1))
 Thus, the legitimate receiver who knows d simply computes
(Pe)d mod n = P and recovers P without having to factor Pe
99
Digital Signatures
•
•
•
A digital signature is an example of using encryption techniques to
provide authentication services in e-commerce applications
A digital signature is a mean of associating a mark unique to an
individual with a body of text
– The mark should be unforgettable, meaning that others should
be able to check that the signature does come from the
originator
A digital signature consists of a string of symbols
– Signature must be different for each use
•
–
This can be achieved by making each digital signature a function
of the message that it is signing, together with a time stamp
Public key techniques are the means creating digital signatures
100
Outline (3/3)
•
•
•
•
•
Privacy Issues and Preservation
Database Survivability
Oracle’s EnterpriseOne DB Security Features
Summary
References
101
Privacy Issues and Preservation (1/2)
Is growing issue for database security and
privacy experts
• Should limit performing large-scale data mining
and analysis
• Violating only single repository’s data security
could expose all data
• Common techniques to address this issue:
•
 Avoid
building mammoth central warehouse as a
mingle repository of vital information
 Intentionally modify or perturb data
102
Privacy Issues and Preservation (2/2)
•
Common techniques to address this issue:
 Avoid
building mammoth central warehouse as a
mingle repository of vital information
 Intentionally modify or perturb data
 Avoiding central warehouses and using distributed
data mining algorithms minimize the exchange of
data needed to develop globally valid model
 Complicated due to its multidisciplinary nature and
the issues related to the subjectivity in the
interpretation of privacy, trust and so on
103
Database Survivability (1/3)
Database systems need to operate and continue
their function, even with reduced capabilities,
despite disruptive events from warfare attack
• DBMS should be able to do the following:
•
 Confinement
Take immediate action to eliminate the attacker’s access
 Isolate and contain the problem from further spread

–
Damage assessment

Determine the extend of the problem, including failed
functions and corrupted data
104
Database Survivability (2/3)
 Reconfiguration

Reconfigure to allow operations to continue in a degraded
mode while recovery proceeds
 Repair

Recover corrupted or lost data and repair or reinstall failed
system functions to reestablish a normal level of operations
 Fault

treatment
To the extend possible, identify the weaknesses exploited
in the attack and take steps to prevent a recurrence
105
Database Survivability (3/3)
Issues related to DB survivability have not been
sufficiently investigated
• Much more research need to be devoted for
techniques and methodologies that insure
database system survivability
•
106
Outline (3/3)
•
•
•
•
•
Privacy Issues and Preservation
Database Survivability
Oracle’s EnterpriseOne DB Security Features
Summary
References
107
Oracle's EnterpriseOne
•
Oracle's JD Edwards EnterpriseOne is
 an
integrated applications suite of comprehensive
enterprise resource planning software
 S/W that combines business value, standards-based
technology, and deep industry experience into a
business solution with a low total cost of ownership
 offers a choice of databases, operating systems, and
hardware so client can build and expand their IT
solution to meet business requirements
 S/W that offers a set of modules to support a diverse
set of business operations and rapid deployment
108
EnterpriseOne database security
•
•
•
•
•
•
No direct access to database by users
Database access through Proxy users
Security is handled by security middleware
module
Supports multilevel security
Supports role based security
SQL access is limited only to DBA users
109
Multilevel of Security
Application
Action
Row (User, Group, *Public)
Column
Processing Options
Tab
Exit
Push Buttons
Images
Use version
Business Unit security
Use version
Business Unit security
Security Levels/Types
Exclusive Application
Exclusive & Inclusive Row
External Calls
Miscellaneous
Solution Explorer
Portal
Data Browser
Link
Media Objects
Address Book Data
Batch Approval
Additional Security
Address Book Data
Batch Approval
Figure 7
A multilevel security
available in
Enterpriseone
110
Roles Example
Figure 8 – Roles Example
111
Enterprise One Auditing
Auditing is the monitoring and recording of
selected user database actions
• Provides the capability to select specific
columns in a table for auditing
• Enterprise One is configurable to
•
 generate
audit when table records are inserted,
updated, or deleted
 Require an electronic signature approval when a
user tries to change the data on an application or
submit a report
112
Summary
•
•
•
•
•
•
•
Database Security and Authorization
Discretionary Access Control
Mandatory Access Control and Role-Based
Access Control for Multilevel Security
Statistical Database Security
Flow Control
Encryption and Public Key Infrastructures
Database Survivability and the need for further
research
113
References
•
•
•
•
•
Ramez Elmasri and Shamkant B. Navathe, “Fundamentals of
database systems”, Addison Wesley; 4 edition (July 23, 2003)
Stallings, W., Brown, L., “Computer Security: Principles and
Practice”, Prentice Hall, NJ, 2008.
Feikis, J.; , "Secure database management systems," Potentials,
IEEE , vol.18, no.1, pp.17-19, Feb/Mar 1999
Giuri, L.; Iglio, P.; , "A role-based secure database design tool,"
Computer Security Applications Conference, 1996., 12th Annual ,
vol., no., pp.203-212, 9-13 Dec 1996
“Oracle EnterpriseOne Security Principles Rel 8.96 Student Guide”,
Oracle, 2007
114
Q&A
115