1
Q
What is a threat?
A
A threat is any possible event or sequence of actions that might lead to a violation of one or more security goals.
2
Q
What is an attack?
A
An attack is the actual realisation of a threat.
3
Q
Which are examples of an attack?
A
- A hacker breaking into a computer
- Disclosure of private emails
- An unauthorized change in financial data
- A hacker shutting down a website
- Impersonation of people to order services or goods
4
Q
How can security goals be defined (in which ways)?
A
- Depending on the application environment
- On a more general, technical way (CIA + AC)
- Confidentiality
- (Data) Integrity
- Availability
- Accountability
- Controlled Access
5
Q
Name some examples of Security Goals based on the application environment.
A
- Banking (fraud detection, transactions identification, PIN protection, customer’s privacy)
- Government (protect sensitive information, electronic signature of documents)
- Public Telecom Providers (restrict access, prevent service interruptions, customer’s privacy)
- All networks (prevent outside penetrations).
6
Q
How “Security goals” are also called? (synonym)
A
Security objectives.
7
Q
Name some examples of Security Goals technically defined:
A
CIA
- Confidentiality (intended audience only, confidentiality of entities = anonymity)
- (Data) Integrity (data modification can be detected, data creators identifiable).
- Availability (services available and function correctly).
8
Q
Which are additional Security Goals:
A
AC
- Accountability (identify the entity responsible for a communication event)
- Controlled Access (authorized entities have access to services/information).
9
Q
Mention some threats Technically Defined:
A
MEALDFS
- Masquerade (entity claiming being another)
- Eavesdropping (entity reading unauthorized information)
- Authorization Violation (usage of service/resources not intended to be used)
- Loss / Modification of (transmitted) Information (data altered or destroyed)
- Denial of Communication Acts (repudiation, entity falsely denying participation)
- Forgery of Information (entity creating information in the name of another)
- Sabotage (actions reducing availability/correct function of services/systems).
10
Q
Explain the cross-table of Threats and Technical Security Goals:
A
11
Q
What does a Network Security Analysis perform?
A
- Evaluates the risk potential of the general threats to user entities.
- Estimates the expenditure (resources, time, etc.) to perform known attacks.
12
Q
Can unknown attacks be assessed?
A
No, it is generally impossible.
13
Q
What are other uses of a Network Security Analysis?
A
- Receive funding for security enhancements.
- Network can be better structured according to attacks on the message level.
14
Q
Name the two attacking communication types on the Message Level:
A
- Passive attacks.
- Active attacks.
15
Q
An example of a passive attack:
A
Eavesdropping (entity reading unauthorized information).
16
Q
Mention examples of Active attacks:
A
DRDMI
- Delay of PDUs
- Replay of PDUs
- Deletion of PDUs
- Modification of PDUs
- Insertion of PDUs.
17
Q
What are PDUs?
A
Protocol Data Units.
18
Q
What does a successful attack launch requires?
A
- No detectable side effects on other communications or transmissions (connection/connectionless)
- No side effects to other PDUs of the same transmission (connection/connectionless) between same entities.
19
Q
Mention some Safeguards against Information Security Threats:
A
- Physical Security (lock or physical access control).
- Personnel Security (identification, screening, training).
- Media Security (safe storage, reproduction and destruction of information, scanning for viruses).
- Lifecycle Controls (programming standards and documentation controls).
- Computer Security (protect devices and information while being stored/processed in computers systems).
- Communications Security (protection of information during system-to-system transport, protection of the communication infrastructure).
20
Q
What are some Safeguards from Communications Security?
A
- Protection of information during system-to-system transport.
- Protection of the communication infrastructure itself.
21
Q
What is the definition of a Security Service and its properties?
A
- Security Service: an abstract service seeking to ensure a specific security property. Realized with the help of algorithms and protocols and other conventional means.
22
Q
What is a Cryptographic Algorithm?
A
A mathematical transformation of input data to output data, it can be used in cryptographic protocols.
23
Q
What is a Cryptographic Protocol?
A
A series of steps and message exchanges between entities to achieve a specific security objective.
24
Q
Mention and define some Security Services:
A
- Authentication (the most fundamental, verifies the identity claimed by an entity).
- Integrity (ensures that data created by entities is not modified without detection).
- Confidentiality (ensures secrecy of protected data).
- Access Control (ensures that each identity accesses only authorized or corresponding services/informations).
- Non repudiation (prevents from entities falsely denying participation in a communication exchange).
25
How are Security Supporting Mechanisms classified?
* **General mechanisms**
* Key Management
* Random number generation
* Event detection/security audit trail
* Intrusion detection
* Notarization
* **Communication specific mechanisms**
* Traffic Padding
* Routing Control
26
Define some Security Supporting **General mechanisms**:
* **Key management** (lifecycle of cryptographic keys).
* **Random number generation** (cryptographically secure random numbers).
* **Event detection/security audit trail** (detection and recording of events that could be used for attacks).
* **Intrusion detection** (analysis of recorded security data to detect successful intrusions/attacks).
* **Notarization:** registration of data by a trusted third party that confirms properties (content, creator, time) of the data.
27
Define some Security Supporting **specific** mechanisms:
* **Traffic Padding:** creation of bogus traffic to prevent traffic flow analysis.
* **Routing Control:** influence routing of the PDUs in a Network.
28
What are the different **layers** of Communication Protocol Architectures?
5) **Application** layer
4) **Transport** layer
3) **Network** layer
2) **Data Link** layer
1) **Physical** layer
\*A variation of the OSI Model is used in the lecture.
29
In which 2 **behaviours** are **attack techniques** based on?
* **Passive behaviour**
* **Eavesdropping**
* **Active behaviour**
* **Delay** of PDUs (Protocol Data Units)
* **Replay** of PDUs
* **Deletion** of PDUs
* **Modification** of PDUs
* **Insertion** of PDUs
30
Describe the use of a **(not very) systematic threat analysis** and its drawbacks.
* A technique where an arbitrary threat list is produced by **brainstorming**.
* Drawbacks:
* Questionable **completeness**
* Rationale based on **experience**
* Potential **inconsistencies**
31
Describe what is a **Threat Tree**, its elements and why is it useful.
* Threat Trees are a **systematic threat analysis approach**.
* It postpones the creation of arbitrary threat lists as much as possible.
* It is a tree with:
* **Nodes** (threat levels)
* **Subtrees and child nodes**
* Achieved through refinement for demonstrable **completeness** (so nothing is missing).
* It is useful to gain insight **where to spend resources to decrease system's vulnerability**.
32
How is a Threat Tree created?
Technique:
1. **General threats** are described
2. **Iteratively** introduce details
3. **Nodes** become a root of a subtree to describe threats represented by it
4. Each **leaf** node describes a **threat**
33
Graphically explain the following a threat tree (A):
34
Graphically explain the following a threat tree (B):
35
Describe the steps of a **High Level System Security Engineering Process**:
1. Identify system **architecture** (components and interrelations)
2. **Identify threats, vulnerabilities and attack techniques** (threat tree)
3. Estimate **component risks** using attributes (criticality/effort = risk)
4. **Prioritize** vulnerabilities
5. Identify and install **safeguards** (protection techniques to counter high priority vulnerabilities)
6. Perform potential **iterations** (re-assess risks of the modified system).
Information Security
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