Bài giảng Bảo mật cơ sở dữ liệu: Security models - Trần Thị Kim Chi

SECURITY MODELS
Operating System Security Fundamentals
Tiếp theo bài 1 bắt đầu từ Slide 10 

Giảng Viên: Trần Thị Kim Chi

© FPT Software

1


Agenda

a. Access control
b. Inference and covert channels
c. Open/close policy
d. Database Application Security Models
Discretionary/mandatory access control

© FPT Software

2


Access control
•

•

Access control is a security technique that can
be used to regulate who or what can view or use

resources in a computing environment.
Access control systems perform authorization
identification, authentication, access approval,
and accountability of entities through login
credentials includingpasswords, personal
identification numbers (PINs), biometric scans,
and physical or electronic keys.

© FPT Software

3


Types of Access control
•

There are two main types of access control:
–
–

•

•

Physical,
logical.

Physical access control limits access to
campuses, buildings, rooms and physical IT
assets.

Logical access limits connections to computer
networks, system files and data.

© FPT Software

4


Types of Access control
The four main categories of access control are:
•
Mandatory access control
•
Discretionary access control
•
Role-based access control
•
Rule-based access control

© FPT Software

5


Mandatory access control (MAC)
•

•

Mandatory access control (MAC) is a systemcontrolled policy restricting access to resource

objects (such as data files, devices, systems,
etc.) based on the level of authorization or
clearance of the accessing entity, be it person,
process, or device.
http://
searchsecurity.techtarget.com/definition/mandatory-a

© FPT Software

6


Discretionary access control (DAC)
•

•

Discretionary access control (DAC) is a type of
access control defined
by
the
Trusted Computer System Evaluation Criteria "as
a
means of restricting access to objects based on the
identity of subjects and/or groups to which they belong.
The controls are discretionary in the sense that a subject
with a certain access permission is capable of passing
that permission (perhaps indirectly) on to any other
subject (unless restrained by mandatory access control
)".

Discretionary access control is commonly discussed in
contrast to mandatory access control (MAC, sometimes
termed non-discretionary access control).
© FPT Software

7


Role-based access control (RBAC)
•

•

•

Role-based access control (RBAC) is a method of
regulating access to computer or network resources
based on the roles of individual users within an
enterprise...
http://
searchsecurity.techtarget.com/definition/role-based-access-co
http://
searchsecurity.techtarget.com/tip/Role-based-access-control-f

© FPT Software

8


Rules Based Access Control

•

•

•

Rules Based Access Control is a strategy for managing
user access to one or more systems, where business
changes trigger the application of Rules, which specify
access changes.
Implementation of Rules Based Access Control systems
is feasible so long as the number of triggering business
events and the set of possible actions that follow those
events are both small.
- See more at: />h.TJMhLiGM.dpuf

© FPT Software

9


Authentication Methods
•

Authentication:
–
–

•

Physical authentication:
–
–

•

Verifies user identity
Permits access to the operating system
Allows physical entrance to company property
Magnetic cards and biometric measures

Digital authentication: verifies user identity by digital
means

© FPT Software

10


Authentication Methods
•

•

Digital certificates: digital passport that identifies and
verifies holder of certificate
Digital token (security token):
–
–
–

Small electronic device
Displays a number unique to the token holder; used with the
holder’s PIN as a password
Uses a different password each time

© FPT Software

11


Authentication Methods
•

Digital card:
–
–

–

•

Also known as a security card or smart card
Similar to a credit card; uses an electronic circuit instead of a
magnetic strip
Stores user identification information

Kerberos:
–
–

Developed by MIT
Uses tickets for authentication purposes

© FPT Software

12


Authentication Methods
•

Lightweight Directory Access Protocol (LDAP):
–
–

–

Developed by the University of Michigan
A centralized directory database stores:
•
Users (user name and user ID)
•
Passwords
•
Internal telephone directory
•
Security keys
Efficient for reading but not suited for frequently changing
information

© FPT Software

13


Authentication Methods
•

NTLM:
–
–

•

Developed and used by Microsoft
Employs a challenge/response authentication protocol

Public Key Infrastructure (PKI):
–
–
–

User keeps a private key
Authentication firm holds a public key
Encrypt and decrypt data using both keys

© FPT Software

14

Authentication Methods
•

•

•

RADIUS: used by network devices to provide a
centralized authentication mechanism
Secure Socket Layer (SSL): authentication
information is transmitted over the network in an
encrypted form
Secure Remote Password (SRP):
–
–

Password is not stored locally
Invulnerable to brute force or dictionary attacks

© FPT Software

15


Authorization
•

•

•

Process that decides whether users are permitted to
perform the functions they request
Authorization is not performed until the user is
authenticated
Deals with privileges and rights

© FPT Software

16


Operating System Authentication
•

•

Many databases (including
Microsoft SQL Server 2000)
depend on OS to
authenticate users
Reasons:
–

–

•

Once an intruder is inside the
OS, it is easier to access the
database
Centralize administration of
users

Users must be authenticated
at each level
© FPT Software

17


User Administration
•
•
•
•

Create user accounts
Set password policies
Grant privileges to users
Best practices:
–
–

–
–

Use a consistent naming convention

Always provide a password to an account and force the user to
change it at the first logon
Protect passwords
Do not use default passwords

© FPT Software

18


Creating a SQL Server User
•

•
•

•

Create a login ID first; controls access to SQL Server
system
Associate login ID with a database user
Must be member of fixed server roles (SYSADMIN or
SECURITYADMIN)
Two types of login IDs:
–
–

Windows Integrated (trusted) login
SQL Server login

© FPT Software

19


Creating Windows Integrated Logins
•

Command line:
–
–

•

SP_GRANTLOGIN system stored procedure
Can be associated local, domain, group usernames

Enterprise Manager:
–
–

Use the Security container
Logins -> New Login

© FPT Software

20


Creating Windows Integrated Logins

© FPT Software

21


Creating SQL Server Logins
•

Command line:
–
–
–

•

SP_ADDLOGIN system stored procedure
Password is encrypted by default
Specify a default database

Enterprise Manager:
–
–
–

Security container
Logins -> New Login
SQL Server Authentication option

© FPT Software

22


Creating SQL Server Logins
•

Command line:
–

–

–

•

SP_ADDLOGIN system
stored procedure
Password is encrypted
by default
Specify
a
default
database

Enterprise Manager:
–
–
–

Security container
Logins -> New Login
SQL
Server
Authentication option
© FPT Software

23


Removing Users
•
•
•

Simple process
Make a backup first
Obtain a written request (for auditing purposes)

© FPT Software

24


SQL Server: Removing Windows
Integrated Logins
•

•

Command line: SP_DENYLOGIN system stored
procedure
Enterprise Manager:
–
–

Highlight the desired login
Choose Delete from the Action menu

© FPT Software

25