Transcript DatabaseSecurity

Database Security
S. Sudarshan
Computer Science and Engg. Dept
I.I.T. Bombay
DB Security, Nov 11,
2003
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Database Security
Database Security - protection from
malicious attempts to steal (view) or
modify data.
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Importance of Data in
Databases
Bank/Demat accounts
Salary
Income tax data
Credit card
University admissions, marks/grades
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Levels of Data Security
Human level: Corrupt/careless User
Network/User Interface
Database application program
Database system
Operating System
Physical level
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Levels of Security Outside of
Database
Physical level
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Traditional lock-and-key security
Protection from floods, fire, etc.
Remote backup for disaster recovery
Operating system level
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Operating system administrators (also known as
super-users) can do anything they want to the
database!
Good operating system level security is required
Windows viruses allow intruders to become “superusers”!
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Security (Cont.)
Network level: must use encryption to
prevent
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Eavesdropping: unauthorized reading of
messages
Masquerading:
 pretending to be an authorized
user or legitimate site, or
 sending messages supposedly
from authorized users
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Security at the
Database/Application Program
Authentication and
authorization
mechanisms to allow
specific users access
only to required data
Authentication: who
are you? Prove it!
Authorization: what
you are allowed to do
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Database vs. Application
Application authenticates/authorizes
users
Application itself authenticates itself to
database

Database password
Application
Program
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Database
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User Authentication
Password

Most users abuse passwords. For e.g.
 Easy to guess password
 Share passwords with others
Smartcards
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Need smartcard
+ a PIN or password
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Bill Gates
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Authorization
Different
authorizations for
different users

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Accounts clerk vs.
Accounts manager vs.
End users
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Authorization
Forms of authorization on (parts of) the
database:
Read authorization - allows reading, but
not modification of data.
Insert authorization - allows insertion of
new data, but not modification of existing
data.
Update authorization - allows modification,
but not deletion of data.
Delete authorization - allows deletion of
data
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Application Authorization
Applications authenticate end users and
decide what interfaces to give to whom

Screen level authorization
Central authentication systems allow users to
be authenticated centrally

LDAP often used for this
Single sign-on: authenticate once, and access
multiple applications without fresh
authentication

Microsoft passport, PubCookie etc
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Application Security
Applications are often the biggest
source of insecurity
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Poor coding of application may allow
unauthorized access
Application code may be very big, easy to
make mistakes and leave security holes
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Insider vs. Outsider Attack
Most people worry about outsider
attack
Most organizations are also highly
vulnerable to insider attacks

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E.g. Indira Gandhi
Luckily most programmers are honest
souls!
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Almighty Application
Programmers/Administrators
Have password to database, can update
anything!

Digital signatures can help in some situations
 E.g. low update rate data such as land records,
birth/death data

More people with access  more danger
Application program has database password

Anyone who manages to seize control of the
application programme can do anything to the
database.
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Dealing with Insider Attacks
Audit trails: record of all (update) activity on
the database: who did what, when
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Database needs to ensure these can’t be turned
off, and turned on again after doing damage
Supported by most commercial database systems
Sys-admin should periodically review audit trail
Don’t give database password to
development team, keep it with a few system
administrators
Multiple copies for security
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Anecdotes
SQL/Slammer
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Attacked SQLServer, brought our network down,
luckily no data lost/stolen
Database security workshop at IIT Bombay
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Careless coding exposed database password to
outside world
Academic office application at IIT Bombay
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Working on “check-sum” technique to ensure
grades/marks are not changed
Database will accept requests only from machine
running application programme
Other security loopholes no doubt exist
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Summary
Data security is critical
Requires security at different levels
Several technical solutions
But human training is essential
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Acknowledgments
Pictures in this talk stolen from various
web sources!
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Extra Slides
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Network Security
All information must be encrypted to prevent
eavesdropping
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Public/private key encryption widely used
Handled by secure http - https://
Must prevent person-in-the-middle attacks

E.g. someone impersonates seller or bank/credit
card company and fools buyer into revealing
information
 Encrypting messages alone doesn’t solve this problem
 More on this in next slide
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Site Authentication
Digital certificates are used to prevent
impersonation/man-in-the middle attack
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Certification agency creates digital certificate by
encrypting, e.g., site’s public key using its own
private key
 Verifies site identity by external means first!
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Site sends certificate to buyer
Customer uses public key of certification agency to
decrypt certificate and find sites public key
 Man-in-the-middle cannot send fake public key
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Sites public key used for setting up secure
communication
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Secure Payment
Three-way communication between seller,
buyer and credit-card company to make
payment
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Credit card company credits amount to seller
Credit card company consolidates all payments
from a buyer and collects them together
 E.g. via buyer’s bank through physical/electronic
check payment
Several secure payment protocols
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E.g. Secure Electronic Transaction (SET)
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