1. Protection and security are mechanisms used in operating systems to control access to resources and safeguard them from threats. Protection focuses on internal threats while security addresses external threats. 2. Protection involves setting and changing access permissions for resources and checking access for users. Security involves authenticating users, adding/removing them, and using anti-malware software to protect from external threats. 3. A security model like the access matrix model defines the set of subjects, objects, and access rules to represent an organization's security policy for controlling access between users and resources.

1. Protection and Security
GROUP 7

2. members
OPULOT PHILIP.A
NANTEGE BRIDGET
NJAWEZI EZEKIEL
NYUMBI SHARRIFU
MBADHI BARNABAS
OMOIT ANDREW

3. Protection
Definitions
• Protection: It refers to a mechanisim for controling the access of
programs, processes, or users to the resouces defined by an Operating
system.
it involves guarding a user's data and programs against interference by
other authorized users of the system.

4. Why we need protection
-to prevent mischievous
-to prevent intential violation of an access restriction by a
user
-to ensure that each program component active in a system
uses system resources only in ways consistent with stated
polices

5. Advantages of protection.
- It allows safe sharing of a common logical address space
or common physical address space. Considering the logical
address space, if there is a directory of files that has to be
shared among multiple users, the protection techniques
help to accomplish safe sharing. Considering the physical
address space, multiple users can have access to the
memory.
- it also provides fair and reliable resource usage.

6. Goals of Protection
Operating system consists of a collection of objects
(hardware or software). Each object has a unique name and
can be accessed through a well-defined set of operations.
Protection problem – to ensure that each object is accessed
correctly and only by those processes that are allowed to do
so.

7. FACETS TO PROTECTION OF INFORMATION
There are two facets to protection of information:
- SECRECY; it implise that only authorised users should be
able to access information
- PRIVACY; implises that informtion should be used only for
the purpose(s) for which it is intended and shared
:- Operating sytems focus on guaranteeing secrecy of
information and leaves the issuse of privacy to the users
and their processes.

8. Security
Definitions
Security: It refers to providing protection to computer
system resouces such as CPU(Central Processing Unit),
memory, Disk, software programs
it involves guarding a user's data and programs
against interference by external entities. eg unauthorized
persons.

9. Security Attributes
Security is defined by three attributes: confidentiality,
integrity, and availability.
Confidentiality is the prevention of unauthorized
modification of information and resources.
Integrity is the prevention of unauthorized users.
Availability is the prevention of unauthorized withholding
of information or resources.

10. Reasons for taking security measures
- To prevent loss of data
- To prevent corruption of data
- To prevent compromise of data
- To prevent theft of data
- To prevent sabotage

11. Security Threats
The external threats can be of two types as direct threats
and indirect threats.
A direct threat is an attack on the system from a hacker or
a disgruntled insider.
An indirect threat is a random attack such as a computer
virus, worm, Trojan horse, etc.

12. Intruders
Intruders and viruses are the two most publicized security threats.
We identify three classes of intruders:
A masquerador is an unauthorized individual (an outsider) who
penetrates a system to exploit legitimate users’ accounts.
A misfeasor is a legitimate user (an insider) who accesses
resources to which they are not privileged, or who abuses such
privilege.
A clandestine user is an individual (an insider or an outsider) who
seizes control of a system to evade auditing controls, or to
suppress audit collection.

13. Malicious Software(program threats)
The most sophisticated threats to computer systems are through malicious software, sometimes
called malware. Malware attempts to cause damage to, or consume the resources of, a target
system.
Malware can be divided into programs that can operate independently, and those that need a
host program; and also into programs that can replicate themselves, and those that cannot.
A trap door is a secret entry point into a program, often left by the program’s developers, or
sometimes delivered via a software update.
A logic bomb is code embedded in a program that ”explodes” when certain conditions are
met, e.g. a certain date or the presence of certain files or users. Logic bombs also often
originate with the developers of the software.
A Trojan horse is a useful (or apparently useful) program that contains hidden code to perform
some unwanted or harmful function.

14. A virus is a program that can ”infect” other programs by modification, as well as
causing local damage. Such modification includes a copy of the virus, which
can then spread further to other programs.
A worm is an independent program that spreads via network connections,
typically using either email, remote execution, or remote login to deliver or
execute a copy of itself to or on another system, as well as causing local
damage.
A zombie is an independent program that secretly takes over a system and
uses that system to launch attacks on other systems, thus concealing the
original instigator. Such attacks often involve further replication of the zombie
itself. Zombies are often used in denial-of-service attacks.

15. Authenitcation
Goal of authentication:
Reasonable assurance that anyone who attempts to access
a system or a network is a legitmate user
Three mechanisms include;-
-Password(patterns or pin)
- Physical token or an artifact eg. Swipe cards
-Biometric measures eg.finger prints,facerecogintion
etc

16. Assets and their Vulnerabilities
I.Hardware is mainly vulnerable to interruption, either by theft or by
vandalism. Physical security measures are used to prevent these
attacks.
II.Software is also vulnerable to interruption, as it is very easy to
delete. Backups are used to limit the damage caused by deletion.
Modification or fabrication through alteration (e.g. by viruses) is a
major problem, as it can be hard to spot quickly.
Software is also vulnerable to interception through unauthorized
copying: this problem is still largely unsolved.

17. III.Data is vulnerable in many ways. Interruption can occur
through the simple destruction of data files. Interception can
occur through unauthorized reading of data files, or more
perniciously through unauthorized analysis and aggregation
of data. Modification and fabrication are also obvious
problems with potentially huge consequences.

18. III.Data is vulnerable in many ways. Interruption can occur through the simple
destruction of data files. Interception can occur through unauthorized reading of
data files, or more perniciously through unauthorized analysis and aggregation of
data. Modification and fabrication are also obvious problems with potentially huge
consequences.
IV.Communications are vulnerable to all types of threats. Passive attacks take the
form of eaves dropping, and fall into two categories: reading the contents of a
message, or more subtly, analyzing patterns of traffic to infer the nature of even
secure messages. Passive attacks are hard to detect, so the emphasis is usually
on prevention. Active attacks involve modification of a data stream, or creation of a
false data stream. One entity may masquerade as another (presumably one with
more or different privileges), maybe by capturing and replaying an authentication
sequence. Replay is a similar attack, usually on data. Message contents may also
be modified, often to induce incorrect behaviour in other users. Denial of service
attacks aim to inhibit the normal use of communication facilities. Active attacks are
hard to prevent (entirely), so the emphasis is usually on detection and damage
control.

19. V.Protection
Muti-programming involves the sharing of many resources, including processor, memory,
I/O devices, programs, and data. Protection of such resources runs along the
following spectrum:
- No protection may be adequate e.g. if sensitive procedures are run at separate
times.
- Isolation implies that entities operate separately from each other in the physical sense.
- Share all or nothing implies that an object is either totally private or totally public.
- Share via access limitation implies that different entities enjoy different levels of access
to an object, at the gift of the owner. The Operating System acts as a guard between
entities and objects to enforce correct access.
- Share via dynamic capabilities extends the former to allow rights to be varied
dynamically.
- Limit use of an object implies that not only is access to the object controlled, the use to
which it may be put also varies across entities.
The above spectrum is listed roughly in order of increasing fineness of control for owners,
and also increasing difficulty of implementation.

20. Computer protection and security mechanisms provided by an
operating system must address the following requirements:
1.Confidentiality : (or privacy) the requirement that information maintained by a
computer system be accessible only by authorized parties (users and the
processes that run as/represent those users). Interception occurs when an
unauthorized party gains access to a resource; examples include illicit file copying
and the invocation of programs.
2.Integrity: the requirement that a computer system’s resources can be modified
only by authorized parties. Modification occurs when an unauthorized party not only
gains access to but changes a resource such as data or the execution of a running
process.
3.Availability: the requirement that a computer system be accessible at required
times by authorized parties. Interruption occurs when an unauthorized party
reduces the availability of or to a resource.
4.Authenticity: the requirement that a computer system can verify the identity of a
user. Fabrication occurs when an unauthorized party inserts counterfeit data
amongst valid data.

21. Protection and Security Design Principles
Least privilege: Every object (users and their processes) should work within a minimal set of
privileges; access rights should be obtained by explicit request, and the default level of access
should be “none”.
Economy of mechanisms: security mechanisms should be as small and simple as possible,
aiding in their verification. This implies that they should be integral to an operating system’s
design, and not an afterthought.
Acceptability: security mechanisms must at the same time be robust yet non-intrusive. An
intrusive mechanism is likely to be counter-productive and avoided by users, if possible.
Complete: Mechanisms must be pervasive and access control checked during all operations —
including the tasks of backup and maintenance.
Open design: An operating system’s security should not remain secret, nor be provided by
stealth. Open mechanisms are subject to scrutiny, review, and continued refinement.

22. Security and protection: Policies and Mechanisms
Security policy -Specify whether a person can become a
user of the system. This funtion is
performed by the system adimistrator
mechanisms Add or delete usersVerify whether a person
is an autherised user
Protection policy -Specify whether a user can access a
specific file. The owner of a file performs
this function while creating it
mechanisms Set or change protection of informantion
for a fileChecks whether a file can be
accessed by a user

23. Security models.
Security models can be discretionary or mandatory
- Discretionary
Holders of right can be allowed to transfer them at their
discretion
- Mandatory
Only designated roles are allowed to grant right and user
connot transfer them

24. Consists of three principal componets
-A set of passive object,(files, terminals,devices and other
entities)
-A set of active subjects, which may manipulate the object.
-A set of rules governing the manipulation of objects by
subjects
-Access matrix Model
Objects
Subjects
File 1 File 2 File 3
User 1 r,w r r,w,x
User 2 r r r,w,x
User 3 r,w,x r,w r,w,x

25. - Role Based Acces control
- Enforces access controls depending upon a user role(s)
-Roles represent specific Organistion duties and are
commonly mapped to job titles, for
example.Adimistrator, Developer etc

26. - Take Grant Model
- This model use graphs to model access control
- The graph structure can be represented as an adjancency
matrix and labels on the arcs can be coded as different
values in the matrix., Nodes in the graph are of two types,
one crosseponding to subject and other to object. The
possible access rights are read(r), write(w), take(t) and
grant(g)

27. Security policy verses security model
- Security policy
Outlines several high level points, how the data is
accessed, the amount of security requried and what are the
steps when these requirement are not met
- Security model
The mechanism to support the security policy, these
involves in the design of the security system

28. PROTECTION VERSES SECURITY
Protection Security
By difintion
- a method used in operating systems that manages
threats with the system to maintain the proper
functioning of the system
- a method used in operating systems that handles
the threats from outside of the system
Main focus
- focuses on internal threats of the systems - focuses on external threats to the systems
By functionality
- provides a mechanism for controlling the access to
programs, processes and user resources
- provides a mechanism to safe guard the system
resources and user resources from external users
By mechanism
- involves mechanism such as setting or changing
protection information of a resource and checking
whether that resource is accessible by a user
- involves mechanisms such as adding, deleting
users, verifying whether a specific user is
authorised, using anti-malware software.etc

29. END
THANK YOU