Online CISSP Questions Video

 Packet filtering operates at the network layer of the Open System Interconnection (OSI) model. The OSI model is a conceptual framework that describes how data is transmitted and processed across different layers of a network. The OSI model consists of seven layers: application, presentation, session, transport, network, data link, and physical. The network layer is the third layer from the bottom of the OSI model, and it is responsible for routing and forwarding data packets between different networks or subnets. The network layer uses logical addresses, such as IP addresses, to identify the source and destination of the data packets, and it uses protocols, such as IP, ICMP, or ARP, to perform the routing and forwarding functions.

Packet filtering is a technique that controls the access to a network or a host by inspecting the incoming and outgoing data packets and applying a set of rules or policies to allow or deny them. Packet filtering can be performed by devices, such as routers, firewalls, or proxies, that operate at the network layer of the OSI model. Packet filtering typically examines the network layer header of the data packets, such as the source and destination IP addresses, the protocol type, or the fragmentation flags, and compares them with the predefined rules or policies. Packet filtering can also examine the transport layer header of the data packets, such as the source and destination port numbers, the TCP flags, or the sequence numbers, and compare them with the rules or policies. Packet filtering can provide a basic level of security and performance for a network or a host, but it also has some limitations, such as the inability to inspect the payload or the content of the data packets, the vulnerability to spoofing or fragmentation attacks, or the complexity and maintenance of the rules or policies.

The other options are not techniques that operate at the network layer of the OSI model, but rather at other layers. Port services filtering is a technique that controls the access to a network or a host by inspecting the transport layer header of the data packets and applying a set of rules or policies to allow or deny them based on the port numbers or the services. Port services filtering operates at the transport layer of the OSI model, which is the fourth layer from the bottom. Content filtering is a technique that controls the access to a network or a host by inspecting the application layer payload or the content of the data packets and applying a set of rules or policies to allow or deny them based on the keywords, URLs, file types, or other criteria. Content filtering operates at the application layer of the OSI model, which is the seventh and the topmost layer. Application access control is a technique that controls the access to a network or a host by inspecting the application layer identity or the credentials of the users or the processes and applying a set of rules or policies to allow or deny them based on the roles, permissions, or other attributes. Application access control operates at the application layer of the OSI model, which is the seventh and the topmost layer.

Network Behavior Analysis (NBA) tools are the best network defense against unknown types of attacks or stealth attacks in progress. NBA tools are devices or software that monitor and analyze the network traffic and activities, and detect any anomalies or deviations from the normal or expected behavior. NBA tools use various techniques, such as statistical analysis, machine learning, artificial intelligence, or heuristics, to establish a baseline of the network behavior, and to identify any outliers or indicators of compromise. NBA tools can provide several benefits, such as:

• Detecting unknown types of attacks or stealth attacks that are not signature-based or rule-based, and that can evade or bypass other network defenses, such as firewalls, IDS, or IPS.
• Detecting advanced persistent threats (APTs) that are low and slow, and that can remain undetected for a long time, by correlating and aggregating the network events and data over time and across different sources.
• Detecting insider threats or compromised hosts that are authorized and trusted, but that exhibit malicious or suspicious behavior, by profiling and classifying the network entities and their interactions.
• Providing early warning and alerting of the potential or ongoing attacks, and facilitating the investigation and response of the incidents, by providing rich and contextual information about the network behavior and the attack vectors.

The other options are not the best network defense against unknown types of attacks or stealth attacks in progress, but rather network defenses that have other limitations or drawbacks. Intrusion Prevention Systems (IPS) are devices or software that monitor and block the network traffic and activities that match the predefined signatures or rules of known attacks. IPS can provide a proactive and preventive layer of security, but they cannot detect or stop unknown types of attacks or stealth attacks that do not match any signatures or rules, or that can evade or disable the IPS. Intrusion Detection Systems (IDS) are devices or software that monitor and alert the network traffic and activities that match the predefined signatures or rules of known attacks. IDS can provide a reactive and detective layer of security, but they cannot detect or alert unknown types of attacks or stealth attacks that do not match any signatures or rules, or that can evade or disable the IDS. Stateful firewalls are devices or software that filter and control the network traffic and activities based on the state and context of the network sessions, such as the source and destination IP addresses, port numbers, protocol types, and sequence numbers. Stateful firewalls can provide a granular and dynamic layer of security, but they cannot filter or control unknown types of attacks or stealth attacks that use valid or spoofed network sessions, or that can exploit or bypass the firewall rules.

Data at rest on a Storage Area Network (SAN) is located at the physical layer of the Open System Interconnection (OSI) model. The OSI model is a conceptual framework that describes how data is transmitted and processed across different layers of a network. The OSI model consists of seven layers: application, presentation, session, transport, network, data link, and physical. The physical layer is the lowest layer of the OSI model, and it is responsible for the transmission and reception of raw bits over a physical medium, such as cables, wires, or optical fibers. The physical layer defines the physical characteristics of the medium, such as voltage, frequency, modulation, connectors, etc. The physical layer also deals with the physical topology of the network, such as bus, ring, star, mesh, etc.

A Storage Area Network (SAN) is a dedicated network that provides access to consolidated and block-level data storage. A SAN consists of storage devices, such as disks, tapes, or arrays, that are connected to servers or clients via a network infrastructure, such as switches, routers, or hubs. A SAN allows multiple servers or clients to share the same storage devices, and it provides high performance, availability, scalability, and security for data storage. Data at rest on a SAN is located at the physical layer of the OSI model, because it is stored as raw bits on the physical medium of the storage devices, and it is accessed by the servers or clients through the physical medium of the network infrastructure.

 Implementing logical network segmentation at the switches is the most effective layer of security the organization could have implemented to mitigate the attacker’s ability to gain further information. Logical network segmentation is the process of dividing a network into smaller subnetworks or segments based on criteria such as function, location, or security level. Logical network segmentation can be implemented at the switches, which are devices that operate at the data link layer of the OSI model and forward data packets based on the MAC addresses. Logical network segmentation can provide several benefits, such as:

• Isolating network traffic and reducing congestion and collisions
• Enhancing performance and efficiency of the network
• Improving security and confidentiality of the network
• Restricting the scope and impact of attacks
• Enforcing access control and security policies
• Facilitating monitoring and auditing of the network

Logical network segmentation can mitigate the attacker’s ability to gain further information by limiting the visibility and access of the sniffer to the segment where it is installed. A sniffer is a tool that captures and analyzes the data packets that are transmitted over a network. A sniffer can be used for legitimate purposes, such as troubleshooting, testing, or monitoring the network, or for malicious purposes, such as eavesdropping, stealing, or modifying the data. A sniffer can only capture the data packets that are within its broadcast domain, which is the set of devices that can communicate with each other without a router. By implementing logical network segmentation at the switches, the organization can create multiple broadcast domains and isolate the sensitive or critical data from the compromised segment. This way, the attacker can only see the data packets that belong to the same segment as the sniffer, and not the data packets that belong to other segments. This can prevent the attacker from gaining further information or accessing other resources on the network.

The other options are not the most effective layers of security the organization could have implemented to mitigate the attacker’s ability to gain further information, but rather layers that have other limitations or drawbacks. Implementing packet filtering on the network firewalls is not the most effective layer of security, because packet filtering only examines the network layer header of the data packets, such as the source and destination IP addresses, and does not inspect the payload or the content of the data. Packet filtering can also be bypassed by using techniques such as IP spoofing or fragmentation. Installing Host Based Intrusion Detection Systems (HIDS) is not the most effective layer of security, because HIDS only monitors and detects the activities and events on a single host, and does not prevent or respond to the attacks. HIDS can also be disabled or evaded by the attacker if the host is compromised. Requiring strong authentication for administrators is not the most effective layer of security, because authentication only verifies the identity of the users or processes, and does not protect the data in transit or at rest. Authentication can also be defeated by using techniques such as phishing, keylogging, or credential theft.