Security service categories and authentication in information systems

¶ … worth 2 points. Each problem is worth 4 points. There are 58 points available in this Homework set.

Security service categories

Authentication: This is assurance that a given communicating entity is whoever it claims to be. The authorization problem is usually confused with the authentication one. Several individuals and organizations usually adopt standard security protocols, statutes as well as obligatory regulations on the basis of this assumption. The more precious definition and usage however describes the concept of authorization as the verification of a claim that has been made by an entity that it should be regarded as acting on behalf of a certain particular principle (computer, individual, smart card and the likes) / Authorization on the other hand is the process of verifying that a given subject which has already been authenticated is granted the authority to initiate a certain action/activity.

Access control: This is the prevention of an unauthorized entity from using a given resource. For instance, the service can be used in controlling whoever has the access to a given resource. The conditions of access are also defined by this service as well as the actions that can be initiated by those who are accessing the given resource.

Data confidentiality: This is the protection of system resources from unauthorized disclosure.

Data integrity: The assurance that the information/data that has been received is exactly as it was cent by the legitimate/authorized entity. This is necessary to ensure that the information/data does not have any modification, deletion, insertion as well as replay.

Nonrepudiation: This service is concerned with the provision of protection to the system resources. It protects them against any form of denial by any one of the entities that are involved in the communication process.

Availability services: This service tasked with ensuring that all system resources are easily accessible upon any request by a system entity that is authorized, according to the system's performance specifications.

Problem 1.3

a. Publication containing list of employees to be retrenched as well as personally identifying employee data such as address, age, disciplinary statistics

b. Publications containing results of scientific and social experiments

c. Publication containing financial data relating to active and real-time currency movements (Forex systems)

Problems 1.4

An organization managing public information on its Web server.

Confidentiality- it is public system so no confidentiality

Availability-Needed since public information must be available at all times of the day, month and year

Integrity- high since documents containing public information are subjected to scrutiny for any policy violations

a.A law enforcement organization managing extremely sensitive investigative information.

Confidentiality- high since a breach in confidentiality may pose danger to internal security and may compromise ongoing investigations

Availability-high since the information directly affect security situation in a community

Integrity- high since information contained relates to security.

b.A financial organization managing routine administrative information (not privacy- related information).

Confidentiality- moderate, since information is not security related

Availability- moderate since the management of the administrative information may be done monthly or yearly.

Integrity- high since the information contained affect the books of accounting directly

c. An information system used for large acquisitions in a contracting organization contains both sensitive, pre-solicitation phase contract information and routine administrative information. Assess the impact for the two data sets separately and the information system as a whole,

Confidentiality- moderate, since information is not security related

Availability-moderate -Needed since public information must be available at all times of the day, month and year

Integrity- high since the contracting information usually contains detailed financial estimates

d. A power plant contains a SCADA (supervisory control and data acquisition) system controlling the distribution of electric power for a large military installation.The SCADA system contains both real-time sensor data and routine administrative information. Assess the impact for the two data sets separately and the information system as a whole.

Confidentiality-High since the information could be classifie3d due to military usage

Availability-High since the system controls a real-time scenario

Integrity-High since wrong parameters may lead to a meltdown.

Question 2.8: What are the principal ingredients of a public-key cryptosystem?

The principle ingredients of a public-key cryptosystem are;

Plaintext: This refers to the readable data as well as message that is fed into a given algorithm as the input

Encryption algorithm: This refers to the algorithm that is used in performing various transformations on a given plaintext.

Public and private keys: This refers to a pair of keys selected in a manner that if one is used for data encryption, the other would be used for data decryption. The form of transformation that is carried out by the encryption algorithm is dependent on the private or public key that is employed as the input.

Ciphertext: Cyphertext refers to the scrambled message that is produced as the output of an encryption process.The cyphertext depends on the key and the plaintext. For any given piece of information / message, there are two different keys that are used in producing two totally different ciphertexts.

Decryption algorithm: This refers to the algorithm that effectively accepts the provided ciphertext as well as the matching key that is used to produce the original plaintext.

Question 2.11 What is digital signature?

A digital signature is a form of authentication mechanism that can allow the creator of a given message to attach a code that effectively simulates or acts as a signature. The digital signature is formed by obtaining the hash of the given message and the performing an encryption using the private key of the creator. The digital signature therefore effectively guarantees the source as well as the integrity of the message.

Question 2.12.What is a public-key certificate?

A public-key certificate is made up of a public key as well as a User ID of the owner of the key. The entire block is however signed by a third party who is trusted. The third party in this case is a certificate authority (CA) who is trusted by the general user community like a government agency and/or a financial institution.

Question 4.1

DAC is used to define the basic access control policies to various objects. These are set according to the needs of the object owners. The MAC are access control policies that are system-controlled. The system in this case dictates as well as controls the acess levels to various objects.

Question 4.2

RBAC is a completely separate as well as distinct model from DAC and MAC. There are however several relationships between them. As an example, RBAC can effectively simulate DAC and MAC. MAC can also be employed in the implementation of RBAC whenever the role hierarchy is in the form of a tree as oppose to being a partial order.

Question 4.5

Access right are authorization levels that are set for files, folders, partitions and hard drives in order to dictate the level of access, data manipulation as well as general uses of the computing resources.

Problem 4.3

a.

The advantages of using four modes instead of two are;

The ability to implement a fine-grained security policy

The ability to provide a distinction within system kernel code.

Disadvantages

Uses too much system resources (Memory in particular)

b.

Yes. A case with more than four modes is achievable. Examples are User-mode debugging, Target application execution, Sleep mode and Kernel-mode debugging.

VAX, x86 can support four modes. The earlier archs (Multics) supported even more modes

Chapter 5.5

The concept of cascading authorization is a security access control technique that works whenever two or more subjects are given the permission of granting as well as revoking some aspects of the access rules to other system subjects. The outcome is the creation of a cascade revocation chain.

Question 5.6

An inference threat is recorded of a given user can effectively deduce sensitive data/information from the otherwise non-sensitive data. It can lead to the exposure of confidential information as well as loss of data and its integrity.

Problem 5.5

In order to effectively determine which value of X's successful grants of EMPLOYEE must subjected to revocation, we must form a list of all remaining grants of X's.

USERID

TABLE

READ

DELETE

X

EMPLOYEE

(15,30)

(15)

(30)

The list of X's grant to others must also be drawn

USERID

TABLE

READ

DELETE

Y

EMPLOYEE

(25)

(25)

(325)

The grant of DELETE privilege by X at a time when t-25 must get revoked as a result of its earliest remaining DELETE privilege that was receive at the time t-30. The X's grants if INSERT and READ are however allowed to remain since they are at that moment 'supported' by the incoming grants that occurred at an earlier time.

Chapter 6

6.3. Describe the difference between host-based IDS and network-based IDS

A host-based IDS is installed on a given machine and then performs its duties of monitoring the abnormalities in the oncoming traffic. A network IDS on the other hand resides on a span port of a switch from where it monitors all of the information that emanates from the firewall in to the internal network. A larger network may have several strategically positioned sensors.

6.4. What are the three benefits that can be provided by an IDS

1. Should an intrusion be promptly detected, the intruder can effectively be identified as then ejected from the system in good time before any damage is done to thedata or the system. The system is important since it can help prevent further damage should the intrusion be detected early

2. An effective IDS can act as an effective deterrent in the prevention of intrusions

3. Intrusion detection allows for the collection of information on various intrusion techniques. The information can then be used in strengthening of the IDS.

6.5

• Ever running

• Tolerant to fault

• Resist to Subversions (Attacks on the IDS)

• Very little overhead

• Highly scalable

• Degradation of the IDS service should never affect the rest of the network.

• Has dynamic configuration to adjust its settings according to the intrusion condition

6.6

Depending on the specific network conditions and the environment, network-based IDS may have advantages as well as disadvantages. The disadvantages may include a higher learning curve in the installation, editing as well as maintenance of the software. One must be familiar with the command line interface of some of the software. The creation of the policy as well as editing of the policy posses another challenge. The advantages include;

Running of software like Tripwire on a platform which is Unix-based can be very daunting for a person who is not familiar with the system. The intruder Alert has both negative ands positive aspects. One advantage is that it is designed to easily integrate with other systems such as NetProwler, an network-based IDS