DEFI

Question 1

Elements of Security

Answer 1

• assets,
• threats,
• vulnerabilities,
• impact,
• risk,
• safeguards,
• residual risk,
• constraints.

Question 2

Assets

Answer 2

Everything that has a value

• Information and Data,
• Hardware,
• Software,
• other Equipment,
• documents,
• services,
• “trust” in services,
• personell,
• A organization’s image

Question 3

Threats

Answer 3

Everything that potentially harms Assets

• errors,
• faults,
• misuse and theft,
• malicious code,
• hacking,
• sabotage,
• espionage,…

Question 4

Vulnerabilities

Answer 4

“Vulnerabilities are weaknesses which allow a threat to occur”
(Vulns do not neccesarily cause damage)

• Insecure Communication
• Poorly trained staff
• trivial passwords
• poor access control
• lack of back-ups

Question 5

safeguards

Answer 5

Means to reduce threats or vulnerabilities

Example: Access Control, Encryption, training of personell,…

• ETSI Baseline Security Standard
• NIST Computer Security Handbook
• ISO TC 68 Banking and Related Financial Services - Information Security Guidelines

Question 6

Risks

Answer 6

Risk is a Function of

• Assets
• Threats
• Vulnerabilities
• Safeguards

There always remains a residual Risk

Question 7

Relations

Answer 7

Question 8

Confidentiality

Answer 8

• No unauthorized access to Information
• sometimes security and confidentiality are use as synonyms

Question 9

Integrity

Answer 9

• No unauthorized modification of information/resources
• Everything is as it is supposed to be

Question 10

Availability

Answer 10

No unauthorized denial of access to information / resources

Question 11

denial of service

Answer 11

prevention of authorised access of resources or the delaying of time-critical operations

⇒ hard to prevent in real life

Question 12

Privacy and Secrecy

Answer 12

• protection of personal data
• protection of data belonging to an organisation

Question 13

property

Answer 13

• property is any attribute that can be quantitatively evaluated
• tempurature, pressur, velocity are properties

Question 14

state

Answer 14

• state of an object is its condition described by a list of properties
• temperature and pressure may describe the state of a gas

Question 15

integrity property or state

Answer 15

• integrity is a property (of data, of a system)
• data integrity is a specific state of data that is verifiable

Question 16

integrity a detective or preventative mechanism?

Answer 16

Integrity services are classified according to the following criteria

type of protection they support

1. prevention of integrity compromise
2. detection of integrity compromise

data integrity mechanisms can be detective or preventative

• most well known mechanisms are detective (e.g. MAC, Digital Siganture)

Question 17

Security Evaluation

Answer 17

“Security evaluation checks whether a product delivers a promised security service. ”

• A high level of Assurance-Level implies an inspection of a system at a very detailed level.
• Complex systems and a high levels of assurance tend to me mutually exclusive

Question 18

Security Policy

Answer 18

Specification of Security Properties of a System

• define goals that can be reached with security measures
• often written down in Natural language
• should be aligned with the real world they refer to

E.g. two employees are needed to open the safe with confidential documents, only possible between 9 and 4

→ An electronic System might enforce an equivalent policy

Question 19

Data origin authentication

Answer 19

• Data origin authentication is the assurance that a given entity was the original source of received data
• Data integrity is the assurance that data has not been altered in an unauthorised (which includes accidental) manner.

Question 20

Difference DOA from Integrity

Answer 20

• Data origin authentication is the assurance that a given entity was the original source of received data.
• Data integrity is the assurance that data has not been altered in an unauthorised (which includes accidental) manner.

Different from Integrity, see the following relation:

• “Data origin authentication is a stronger notion than data integrity”
• “Confidentiality does not imply data origin authentication”
• “Confidentiality does not imply data integrity

Question 21

Dual of integrity difference from “no integrity”

Answer 21

Contingency

Contingency describes the verifiable state that the data’s integrity is intended to be unknown. Data in that state is said to be contingent.

• Contingency is a verifiable property explicitly established by the applied protection mechanism and not an accidental state.
• Allows an entity to repudiate the data, but not its creation
• Data origin authentication is required for “intend” to be meaningful

Question 22

Non-Repudiation - Differences and Relations

Answer 22

• … assurance that entity cannot deny a previous commitment or action
• … assurance that original source of some data cannot deny to a third party that this is the case

Diffrence DOA

• “Data origin authenticationis theassurancethata given entity was theoriginal source of received data.”
• “Non-repudiation of a source is a stronger notion than data origin authentication”

Question 23

Entity Authentication - Difference and Relations

Answer 23

… is the assurance that a given entity is involved and currently active in a communication session

DIfference to DOA:

• “Data origin authenticationon its own is only concerned with the origin of data, not whether the sender of data is currently active.”
• “Data origin authentication plus a freshness check can provide entity authentication”

Question 24

Classifying Attackers

Answer 24

• Class I: “Clever Outsiders”.
• Intelligent,
• has technical knowledge and simple equipment.
• Tend to use known vulnerabilities of systems
• Class II: “Knowledgeable Insiders”.
• Technical Training/Education,
• in-depth knowledge of systems,
• has access to sophisticated equipment
• Class III: “Funded Organizations”.
• Teams of specialists,
• access to relevant (Insider-) Information,
• access to dedicated euquipment and significant resources (time, money)

Question 25

Approaches to Security

Answer 25

• Virtualization: Giving code the illusion that it is in an environment other than the one it is actually being executed on.
• Attestation: Providing systems the means to attest or verify the integrity of their components. (Needs a root of “trust”)
• Acceleration: Adding hardware support to reduce the runtime overheads of security features.
• Tagging: Memory locations are “tagged” with metadata, which can signal things like data types or permission levels.
• Formal methods: Construct logical proofs to verify or disprove certain properties about a system.
• Cryptography: Encrypt/protect information using cryptosystems.
• Isolation: Keep trusted and untrusted components separate from eachother, and carefully monitor any interaction between the two.
• Flow Approaches: Everything is an object with data and metadata. As computations are applied to data, shadow computations occur on the corresponding metadata, which detect and report illegitimate data modifications.
• Moving Target Approaches: Almost all attacks (will) have defenses, and all defenses (will) have attacks. If attackers and defenders are constantly trying to better each other, moving target approaches minimize the advantage to the attackers by changing how the system/defenses work over time.
• Diversification: If each system were distinct, it would force the attacker to prepare bespoke exploits, increasing their work and reducing their profits.
• Anomaly detection: This paradigm is borne out of the philosophy that systems will always be insecure, irrespective of the presence of other security mechanisms. The goal is to monitor systems for abnormal or unusual behavior, which may indicate an adversarial attack on a system’s security.