sesi-8-dbSecurity

Teknologi Sistem Basis Data – MTI Fasilkom 2010

Session 8Database Security

Achmad Nizar Hidayanto ([email protected])

Most slides are adopted from the textbook Thomas Connolly, Carolyn Begg, Database Systems 5th Ed. 2010Addison Wesley© Chapter 20

Part of theses slides adopted from presentation from S. SudarshanComputer Science and Eng. Dept I.I.T. Bombay, “Database & Application Security”.

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Objectives The scope of database security. Why database security is a serious concern for an

organization. The type of threats that can affect a database system. How to protect a computer system using computer-based

controls. The security measures provided by Microsoft Office

Access DBMSs. Approaches for securing a DBMS on the Web.

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Database Security Mechanisms that protect the database

against intentional or accidental threats.

Security considerations do not only apply to the data held in a database. Breaches of security may affect other parts of the system, which may in turn affect the database.

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Importance of Data Bank accounts Credit card, Salary, Income tax data University admissions, marks/grades Land records, licenses Data = crown jewels for organizations Tax report Recent headlines:

Personal information of millions of credit card users stolen

Century Data ? Tax Data ?

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Database Security Data is a valuable resource that must be

strictly controlled and managed, as with any corporate resource.

Part or all of the corporate data may have strategic importance and therefore needs to be kept secure and confidential.

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Database Security Involves measures to avoid:

Theft and fraud Loss of confidentiality (secrecy) Loss of privacy Loss of integrity Loss of availability

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Database Security Threat

Any situation or event, whether intentional or unintentional, that will adversely affect a system and consequently an organization.

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Summary of Threats to Computer Systems

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Typical Multi-user Computer Environment

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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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Physical/OS Security Physical level

Traditional lock-and-key security Protection from floods, fire, etc.

E.g. WTC (9/11).

Protection from administrator error E.g. delete critical files

Solution Remote backup for disaster recovery Plus archival backup (e.g. DVDs/tapes)

Operating system level Protection from virus/worm attacks critical

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Database Encryption

e.g. What if you store critical data? Partial solution: encrypt the database at storage level,

transparent to application Whole database/file/relation

Unit of encryption: page Column encryption

Main issue: key management E.g. user provides decryption key (password) when database is started up

Supported by many database systems Standard practice now to encrypt credit card information, and other

sensitive information

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Security (Cont.)

Network level: must use encryption to prevent 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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Network Security All information must be encrypted to prevent

eavesdropping 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

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Site Authentication

Digital certificates are used in https to prevent impersonation/man-in-the middle attack 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! 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

Sites public key used for setting up secure communication

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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

DatabaseApplicationProgram

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User Authentication

Password Most users abuse passwords. For e.g.

Easy to guess passwordShare passwords with others

Smartcards Need smartcard + a PIN or password

Bill Gates

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User Authentication Central authentication systems allow users to be

authenticated centrally LDAP or MS Active Directory often used for central

authentication and user management in organizations Single sign-on: authenticate once, and access

multiple applications without fresh authentication Microsoft passport, PubCookie etc Avoids plethora of passwords Password only given to central site, not to applications

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Countermeasures – Computer-Based Controls

Concerned with physical controls to administrative procedures and includes: Authorization Access controls Views Backup and recovery Integrity Encryption RAID technology

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Countermeasures – Computer-Based Controls

Authorization The granting of a right or privilege, which

enables a subject to legitimately have access to a system or a system’s object.

Authentication is a mechanism that determines whether a user is, who he or she claims to be.

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Countermeasures – Computer-Based Controls

Access control Based on the granting and revoking of

privileges. A privilege allows a user to create or access

(that is read, write, or modify) some database object (such as a relation, view, and index) or to run certain DBMS utilities.

Privileges are granted to users to accomplish the tasks required for their jobs.

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Countermeasures – Computer-Based Controls

Most DBMS provide an approach called Discretionary Access Control (DAC).

SQL standard supports DAC through the GRANT and REVOKE commands.

The GRANT command gives privileges to users, and the REVOKE command takes away privileges.

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Countermeasures – Computer-Based Controls

View Is the dynamic result of one or more

relational operations operating on the base relations to produce another relation.

A view is a virtual relation that does not actually exist in the database, but is produced upon request by a particular user, at the time of request.

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Countermeasures – Computer-Based Controls Backup

Process of periodically taking a copy of the database and log file (and possibly programs) to offline storage media.

Journaling Process of keeping and maintaining a log file (or

journal) of all changes made to database to enable effective recovery in event of failure.

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Countermeasures – Computer-Based Controls

Integrity Prevents data from becoming invalid, and

hence giving misleading or incorrect results.

Encryption The encoding of the data by a special

algorithm that renders the data unreadable by any program without the decryption key.

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RAID (Redundant Array of Independent Disks) Technology Hardware that the DBMS is running on

must be fault-tolerant, meaning that the DBMS should continue to operate even if one of the hardware components fails.

Suggests having redundant components that can be seamlessly integrated into the working system whenever there is one or more component failures.

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RAID (Redundant Array of Independent Disks) Technology The main hardware components that

should be fault-tolerant include disk drives, disk controllers, CPU, power supplies, and cooling fans.

Disk drives are the most vulnerable components with the shortest times between failure of any of the hardware components.

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RAID (Redundant Array of Independent Disks) Technology One solution is to provide a large disk

array comprising an arrangement of several independent disks that are organized to improve reliability and at the same time increase performance.

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RAID (Redundant Array of Independent Disks) Technology Performance is increased through data

striping: the data is segmented into equal-size partitions (the striping unit), which are transparently distributed across multiple disks.

Reliability is improved through storing redundant information across the disks using a parity scheme or an error-correcting scheme.

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RAID (Redundant Array of Independent Disks) Technology There are a number of different disk

configurations called RAID levels. RAID 0 Nonredundant RAID 1 Mirrored RAID 2 Memory-Style Error-Correcting Codes RAID 3 Bit-Interleaved Parity RAID 4 Block-Interleaved Parity RAID 5 Block-Interleaved Distributed Parity etc

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RAID 0 and RAID 1

RAID Level 0: Block striping; non-redundant. Used in high-performance applications where data lose is not critical.

RAID Level 1: Mirrored disks with block stripingOffers best write performance. Popular for applications such as storing log files in a database system.

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RAID 2 and RAID 3RAID Level 2: Memory-Style Error-Correcting-Codes (ECC) with bit striping.RAID Level 3: Bit-Interleaved Parity

•a single parity bit is enough for error correction and detection•When writing data, corresponding parity bits must also be computed and written to a parity bit disk•Subsumes Level 2 (provides all its benefits, at lower cost).

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RAID 4 and RAID 5RAID Level 4

•Provides higher I/O rates for independent block reads than Level 3 •Provides high transfer rates for reads of multiple blocks than no-striping

•Before writing a block, parity data must be computed •Parity block becomes a bottleneck for independent block writes since every block write also writes to parity disk

RAID Level 5: •Block-Interleaved Distributed Parity; partitions data and parity among all N + 1 disks, rather than storing data in N disks and parity in 1 disk.

•E.g., with 5 disks, parity block for nth set of blocks is stored on disk (n mod 5) + 1, with the data blocks stored on the other 4 disks.

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Security in Microsoft Office Access DBMS Provides two methods for securing a

database: setting a password for opening a database

(system security); user-level security, which can be used to

limit the parts of the database that a user can read or update (data security).

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Securing the DreamHome database using a password

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User and Group Accounts dialog box for the DreamHome database

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User and Group Permissions dialog box

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Creation of a new user with password authentication set

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Log on dialog box

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Setting the Insert, Select, and Update privileges

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DBMSs and Web Security Internet communication relies on TCP/IP

as the underlying protocol. However, TCP/IP and HTTP were not designed with security in mind. Without special software, all Internet traffic travels ‘in the clear’ and anyone who monitors traffic can read it.

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DBMSs and Web Security Must ensure while transmitting

information over the Internet that: inaccessible to anyone but sender and receiver

(privacy); not changed during transmission (integrity); receiver can be sure it came from sender

(authenticity); sender can be sure receiver is genuine (non-

fabrication); sender cannot deny he or she sent it (non-

repudiation).

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DBMSs and Web Security Measures include:

Proxy servers Firewalls Message digest algorithms and digital signatures Digital certificates Kerberos Secure sockets layer (SSL) and Secure HTTP (S-HTTP) Secure Electronic Transactions (SET) and Secure Transaction

Technology (SST) Java security ActiveX security

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How Secure Electronic Transactions (SET) Works