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1. Introduction to Computer Science
2007-2008
Computer Security
and Risks

2. 4626. Introd to Computer Science
Aims
• Describing several types of computer crime
• Describing the major security issues that
computer users have to face
• Describing how it affects to personal privacy
• Explaining the relationship between security
and computer reliability

3. 4626. Introd to Computer Science
Crime accomplished through computer tech.
• widely extended: easiness of computer
usage
• most of them committed by company
insiders
• high cost: foresight + repair
Current threats
• spoofing (or phishing): identity theft
Computer Crime

4. 4626. Introd to Computer Science
Software Piracy
• Illegal duplication of copyrighted software
• Reasons:
• price of software
• means to create copies
How many pirate programs do
you have?

5. 4626. Introd to Computer Science
Authorship rights
Industrial property
Intellectual Property
• Privileges granted over intangible goods with
financial value
• They are defined over
• copyright
• commercial secret
• patents
• trademarks
• Software is covered by copyright

6. 4626. Introd to Computer Science
Computer Sabotage
• Trojan horses
• Viruses
• Worms
Use of malware to spoil
hardware & software

7. 4626. Introd to Computer Science
Trojans
• hidden inside programs that perform
useful tasks
• logic bombs: programmed to ‘attack’ in
response to a particular event (e.g. time
bombs)
• solutions
• software from reliable sources
(avoids)
• anti-trojan (detects)
• firewall -output- (blocks)

8. 4626. Introd to Computer Science
Viruses
• as biological ones
• invade programs and use them to reproduce
themselves
• operative system specific
• solution:
• use carefully removable media (avoids)
• antivirus (detects and cleans)

9. 4626. Introd to Computer Science
Worms
• as viruses: use computers to
reproduce themselves
• autonomous spread through
computer networks
• solution:
• email from confident sources
(avoids)
• firewall -input- (blocks)
• security patches

10. 4626. Introd to Computer Science
Hacking
• Discovering and exploiting
computer system failures
• Reasons:
• curiosity
• intellectual challenge
• Cracking = criminal hacking

11. 4626. Introd to Computer Science
Reducing Risks
• to work properly
• to guarantee access
to information only
to granted users
• to guarantee
privacy
Information systems have to be protected...

12. 4626. Introd to Computer Science
Physical Access
Restrictions
• something you have (card)
• something you know (password)
• something you do (signature)
• something about you (scans)
Only authorised staff
have access to the equipment
Security checks based on…

13. How
can we protect
sensitive
information?

14. 1. protect hw

15. UPS
• uninterruptible
power supply
• protects data
during power
failures (minutes)
• give users time
to switch off
the system

16. 4626. Introd to Computer Science
Surge
protectors
• shield computers from power
spikes
• protect the computer from
physical damage

17. 2. protect data

18. 4626. Introd to Computer Science
Passwords
• which kind of password do you use?
• how frequently do you change your passwords?
• how many passwords do you use?
The most common tool,
but carefully chosen
Never use a word or your b-day!!

19. Firewalls
• guard against
unauthorised access
• blocks accessing ports for
input and output
• by hardware or software

20. 4626. Introd to Computer Science
Encryption
• keys to code messages
and documents
• symmetric:
common key
• asymmetric:
public / private keys

21. 4626. Introd to Computer Science
Audit Control SW
• Records computer
transactions
• Auditors can trace and
identify suspicious activities

22. 2. replicate

23. 4626. Introd to Computer Science
Backup Copies
• periodic copies of
important information
• for companies, it is
recommended that copies
be stored in a different
location

24. 4626. Introd to Computer Science
RAID
• Redundant Array of
Independent Disks
• multiple disks as
one logical unit
• mirroring: data
redundancy