Presentation on Database Security in DBMS

What is data security?
• Data security is the protection of the data from unauthorized users.
• Only the authorized users are allowed to access the data.
• Most of the users are allowed to access a part of database i.e., the data that is
related to them or related to their department.
• Mostly, the DBA or head of department can access all the data in the database.
• Some users may be permitted only to retrieve data, whereas others are allowed
to retrieve as well as to update data.

Security v/s Integrity
Security Integrity
Data security deals with protection of
data.
Data integrity deals with the validity of
data.
Data security is making sure that only the
people who should have access to the
data are the only ones who can access the
data.
Data integrity is making sure that the data
is correct and not corrupt.
Data security avoids from unauthorized
access of data.
Data integrity avoids from human errors,
when data is entered.
Data security is implemented through
user account (passwords).
Data integrity is implemented through
constraints such as Primary key, Foreign
key, Check constraints etc.

Database security issues
 Database security a broad area
 Legal, ethical, policy, and system-related issues
 Threats to databases
 Loss of integrity

Improper modification of information
 Loss of availability

Legitimate user cannot access data objects
 Loss of confidentiality

Unauthorized disclosure of confidential information

 Threats to databases
 Loss of integrity
 Loss of availability
 Loss of confidentiality
 To protect databases against these types of threats four kinds
of countermeasures can be implemented:
 Access control
 Inference control
 Flow control
 Encryption

 A DBMS typically 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 security mechanisms
 Mandatory security mechanisms

Control Measures
 Control measures
 Access control

Handled by creating user accounts and passwords
 Inference control (for statistical DBs)

Must ensure information about individuals cannot be accessed.

database security discipline that protects data so that it can be
published without revealing confidential information
 Flow control

Prevents information from flowing to unauthorized users
 Data encryption

Used to protect sensitive transmitted data

 Database administrator (DBA)
 Central authority for administering database system
 Superuser or system account
 DBA-privileged commands
 Account creation
 Privilege granting
 Privilege revocation
 Security level assignment
Database Security and DBA

Access control methods of data security
• There are three different methods of data access control:
1. Discretionary access control (DAC)
2. Mandatory access control (MAC)
3. Role based access control (RBAC)

Discretionary access control
• In discretionary access control (DAC), the owner of the object specifies
(decides) which subjects (user) can access the object.
• In this method a single user can have different rights on different objects, as
well as different user can have different rights on the same objects.
RollNo Name Branch Sem SPI BL
101 Raju CE 3 6 1
101 Mitesh CE 5 9 0
102 Jay CE 3 8 0
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• Read and Write (Full rights)
• On entire table (3 tuples)
• Read and Write (Full rights)
• Partial table (2 or 1 tuples)
• Read (Partial rights)
• Partial table (Only 1 tuple)
• Read (Partial rights)
• Partial table (2 or 1 tuples)

• SQL support discretionary access control through the GRANT and REVOKE
commands.
• GRANT
• This command gives rights to user for an object.
• Syntax:- GRANT privilege ON object TO user [WITH GRANT OPTION]
• REVOKE
• This command takes back rights from user for an object.
• Syntax:- REVOKE privilege ON object FROM user {RESTRICT/CASCADE}

 Relation or table level (cont’d.)
 Each relation R assigned an owner account
 Owner of a relation given all privileges on that relation
 Owner can grant privileges to other users on any
owned relation

SELECT (retrieval or read) privilege on R

Modification privilege on R

References privilege on R

 Consider owner A of relation R and other party B
 A can create view V of R that includes only attributes A
wants B to access

Grant SELECT on V to B
 Can define the view with a query that selects only
those tuples from R that A wants B to access

Revocation and Propagation of Privileges
 Revoking of Privileges
 Useful for granting a privilege temporarily
 REVOKE command used to cancel a privilege
 Propagation of privileges using the GRANT OPTION
 If GRANT OPTION is given, B can grant privilege to
other accounts
 DBMS must keep track of how privileges were granted
if DBMS allows propagation

Simple GRANT Syntax
 GRANT priv_type [, priv_type] ...
ON object_type
TO user [user] ...
[WITH GRANT OPTION ]

Example: Granting/Revoking Privileges
 DBA to A1
 GRANT CREATETAB TO A1;
 A1 can create new tables
 A1 creates relations Emp and Dept
 A1 to A2
 GRANT INSERT DELETE on Emp, Dept TO A2;
 A2 was not given the WITH GRANT OPTION
 A2 cannot give privilege to other users

Example: Granting/Revoking Privileges
 A1 to A3
 GRANT SELECT On Emp, Dept TO A3 WITH GRANT
OPTION;
 A3 given the WITH GRANT OPTION
 A3 can give privilege to other users
 A3 to A4
 GRANT SELECT On Emp TO A4;
 A4 cannot propagate the SELECT privilege

Mandatory access control
• In this method individual user cannot get rights.
• But all the users as well as all the objects are classified into different categories.
• Each user is assigned a clearance level and each object is assigned a security level.
• A user can access object of particular security level only if he has proper clearance level.
• The DBMS (system) determines whether the given user can read or write a given object
based on some rules.
• This rule makes sure that sensitive data can never be passed to a user without necessary
clearance.
Top Secret Secret Confidential Unclassified

Mandatory access control
• Mandatory access control technique for multi-level security uses four components:
• Subjects:- Such as users, accounts, programs etc.
• Objects:- Such as relation (table), tuples (records), attribute (column), view etc.
• Clearance level:- Such as top secret (TS), secret (S), confidential (C), Unclassified (U). Each subject
is classified into one of these four classes.
• Security level:- Such as top secret (TS), secret (S), confidential (C), Unclassified (U). Each object is
classified into one of these four classes.
• In the above system TS>S>C>U, where TS>S means class TS object is more sensitive
than class S object.
• A user can access data by following two rules
• Security property:-
• Security property states that a subject at a given security level may not read an object at a higher security level.
• Star (*) security property:-
• Star (*) property states that a subject at a given security level may not write to any object at a lower security
level.

Mandatory Access Control
 Mandatory access control
 Additional security policy that classifies data and users
based on security classes
 Typical security classes

Top secret

Secret

Confidential

Unclassified
 Bell-LaPadula model

Subject and object classifications

 Simple security property
 Subject S not allowed read access to object O unless
class(S)≥class(O)
 Star property (*-property)
 Subject not allowed to write an object unless
class(S)≤class(O)
 Prevent information from flowing from higher to lower
classifications
 Attribute values and tuples considered as data objects
Mandatory Access Control

Role-Based Access Control
 Permissions associated with organizational roles
 Users are assigned to appropriate roles
 Can be used with traditional discretionary and
mandatory access control
 Mutual exclusion of roles
 Both roles cannot be used simultaneously
 Identity management

Role based access control (RBAC) rules
• It restricts database access based on a person's role within an organization. The
roles in RBAC refer to the levels of access that employees have to the network.
• Employees are only allowed to access the information necessary to effectively
perform their job duties.
• Access can be based on several factors, such as authority, responsibility, and job
competency.
• In addition, access to computer resources can be limited to specific tasks such as
the ability to view, create, or modify a file.
• Lower-level employees usually do not have access to sensitive data if they do not
need it to fulfil their responsibilities.
• Using RBAC will help in securing your company’s sensitive data and important
applications.

Audit trail (audit log)
• An audit trail (audit log) is a record which will be generated for each and every
transactions.
• It will keep certain information about the transaction.
• An audit trail (audit log) records
• Who (user or the application program and a transaction number)
• When (date and time)
• From Where (location of the user and/or terminal)
• What (identification of the data affected, as well as a before-and-after image of that
portion of the database that was affected by the update operation)

Data encryption
• Data encryption is the process of encoding (translating) a message or
information in such a way that only authorized persons can access it and those
who are not authorized cannot.
• Encryption is the process of translating plaintext data (plaintext) into
something that appears to be meaningless (ciphertext).
• Decryption is the process of converting ciphertext back to plaintext.
• Types of Encryption
• Symmetric key encryption / Private key encryption
• Asymmetric key encryption / Public key encryption

Types of Encryption
• Symmetric key encryption
• Encryption and decryption keys are the same.
• The same key is used by the sender to encrypt the data, and again by the receiver to
decrypt the data.
• Symmetric key encryption is fast in execution.
• Asymmetric key encryption
• Encryption and decryption keys are the different (Public Key and Private Key).
• Messages are encrypted by sender with one key (Public Key) and can be decrypted by
receiver only by the other key (Private Key).
• Asymmetric key encryption is slow in execution due to the high computational burden.

Presentation on Database Security in DBMS

Presentation on Database Security in DBMS

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