2. Computer Security - also known as cyber
security or IT security, is the protection
of computer systems from the theft or damage to
their hardware, software or information, as well as
from disruption or misdirection of the services they
provide.
Network Security - measures to protect data during
their transmission
3. Internet Security - measures to protect data during
their transmission over a collection of interconnected
networks which consists of measures to deter,
prevent, detect, and correct security violations that
involve the transmission & storage of information
5. 1.CONFIDENTIALITY
• Confidentiality refers to protecting
information from being accessed by
unauthorized parties. In other words,
only the people who are authorized to do
so can gain access to sensitive data.
• Imagine your bank records. You should
be able to access them, of course, and
employees at the bank who are helping
you with a transaction should be able to
access them, but no one else should.
6. 2. INTEGRITY
• The second goal of Network Security is
"Integrity". Integrity aims at maintaining
and assuring the accuracy and consistency
of data.
• The function of Integrity is to make sure
that the data is accurate and reliable and is
not changed by unauthorized persons or
hackers.
7. • The data received by the recipient must be exactly
same as the data sent from the sender, without change
in even single bit of data.
• cryptography plays a very major role
in ensuring data integrity.
8. 3. AVAILABILITY
Availability: The third goal of network security is
"Availability".
Availability of information refers to ensuring that
authorized parties are able to access the information when
needed.
Information only has value if the right people can access it
at the right times. Denying access to information has
become a very common attack nowadays.
How does one ensure data availability? Backup is key.
Regularly doing off-site backups can limit the damage
caused by damage to hard drives or natural disasters.
9. LEVELS OF IMPACT
➢ We can define 3 levels of impact from a security
breach
⚫Low
⚫Moderate
⚫High
10. LOW IMPACT
The loss could be expected to have a limited
adverse effect on organizational operations,
organizational assets, or individuals.
The loss of confidentiality, integrity, or availability
might
(i) minor damage to organizational assets;
(ii) minor financial loss; or
(iii) minor harm to individuals.
11. Moderate Impact
The loss could be expected to have a serious adverse
effect on organizational operations, organizational
assets, or individuals.
A serious adverse effect means that, for example, the
loss might
(i) the functions is significantly reduced;
(ii) result in significant damage to organizational
assets;
(iii) result in significant financial loss; or
(iv) result in significant harm to individuals that does
not involve loss of life or serious, life-threatening
injuries.
12. High Impact
The loss could be expected to have a severe or
catastrophic adverse effect on organizational
operations, organizational assets, or individuals.
A severe or catastrophic adverse effect means that,
for example, the loss might
(i) cause a severe degradation
(ii) result in major damage to organizational
assets;
(iii) result in major financial loss; or
(iv) result in severe or catastrophic harm to
individuals involving loss of life or serious life
threatening injuries.
13. Challenges of Computer Security
1. Computer security is not simple
2. One must consider potential (unexpected) attacks
3. Procedures used are often counter-intuitive
4. Must decide where to deploy mechanisms
5. Involve algorithms and secret info (keys)
6. A battle of wits between attacker / admin
7. It is not perceived on benefit until fails
8. Requires constant monitoring
9. Too often an after-thought (not integral)
10. Regarded as impediment to using system
14. Aspects of Security
The 3 aspects of information security:
Security Attack
Security Mechanism
Security Service
Security attack: Any action that compromises the security
of information owned by an organization.
• Security mechanism: A process (or a device) that is
designed to detect, prevent, or recover from a security
attack.
• Security service: A processing or communication service
that enhances the security of the data processing systems
and the information transfers of an organization.
15. Attack - An assault on system security that derives
from an intelligent threat; that is, an intelligent act that
is a deliberate attempt (especially in the sense of a
method or technique) to evade security services and
violate the security policy of a system. There are two
types of attacks.
1. Passive Attack 2. Active Attack
16. Handling AttacksPassive attacks – A passive attack
attempts to learn or make use of
information from the system but
does not affect system resources.
Passive attacks are in the nature of
eavesdropping on, or monitoring of,
transmissions.
These attacks are difficult to detect
because they do not involve any
alteration of the data.
18. Passive Attack: Traffic Analysis
Observe traffic pattern
Traffic analysis - monitor traffic flow to
determine location and identity of
communicating hosts and could observe the
frequency and length of messages being
exchanged
19. Active Attack
Active attacks involve some modification
of the data stream or the creation of a
false stream
It can be subdivided into four categories:
masquerade, replay, modification of
messages, and denial of service:
• Masquerade of one entity as some other
• Replay previous messages
• Modify/alter (part of) messages in transit
to produce an unauthorized effect
• Denial of service - prevents or inhibits
the normal use or management of
24. Model for Network Security
This general model shows that there are four basic tasks in designing a particular security service.
1. Design a suitable algorithm for the security
transformation
2. Generate the secret information (keys)
used by the algorithm
3. Develop methods to distribute and share
the secret information
4. Specify a protocol enabling the principles to
use the transformation and secret information
for a security service
25. Model for Network Access
Security
using this model requires us to:
1. select appropriate gatekeeper
functions to identify users
2. implement security controls to
ensure only authorised users access
designated information or resources
