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CSCI 4130 - Intro to Cybersecurity > Network Security > Flashcards

Network Security Flashcards

(81 cards)

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1
Q

Define

Network Protocol

Network Security

A

Transports data between nodes of a network and defines the syntax/semantics (how)

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2
Q

Define

Layering

Network Security

A

Stacks of protocols for modularization (separation)

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3
Q

What is the TCP/IP Layering?

Network Security

A

Link (data transfer)
Transport (process to process transport)
Netowrk (source to dest route)
Application (supporting network applications)

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4
Q

Define

Internet Protocol

Network Security

A

Connectionless, unreliable, best-effort datagram delivery between any nodes on the Internt with reliance on lower-level layer protocols

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5
Q

Define

IP Address

Network Security

A

4 byte value unqiue to each network separated by .

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6
Q

Components of IP Datagram

Network Security

A
  • Expiration
  • Protocol
  • Source Address
  • Destination Address
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7
Q

Describe

Delivery of an IP datagram: same physical network

Network Security

A

Direct delivery in lower-level

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8
Q

Describe

Delivery of an IP datagram: different physical networks

Network Security

A

Pass through devices of intermediate networks

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9
Q

What are the two intermediate networks?

Network Security

A

Inter-networks: routers
Intra-networks: switches

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10
Q

Define

Ethernet

Network Security

A

Link-layer protocol that includes dest address, source address, and type

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11
Q

Define

Switches

Network Security

A
  • Connects machines in the Local Area Networks (LAN)
  • Stores/forwards Ethernet
  • Examines incoming MAC addresses
  • Maintains a table that maps MAC addresses and their respective ports
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12
Q

Types of Network Attacks

Network Security

A
  • Local Area Network (LAN) Attacks
  • Network Layer Attacks
  • Transport Layer Attacks
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13
Q

Describe

Local Area Network (LAN) Attacks

Network Security

A
  • Impersonate host
  • Denial of service
  • Access information
  • Tamper with delivery mechanisms
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14
Q

Define

Sniffing/Eavesdropping

Network Security

A

Gathering traffic from a local traffic (promiscuous mode) to collect credentials/emails/files, etc.

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15
Q

Can sniffing go undetected?

Network Security

A

Mainly yes but can be detected by software

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16
Q

Define

Address Resolution Spoofing

Network Security

A

Sniffing all traffic between two hosts in a switched environment (intra-network)

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17
Q

How is Address Resolution Spoofing possible?

Network Security

A

Replies in a switched environments don’t need requests to be accepted

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18
Q

Define

Address Resolution Protocol (ARP)

Network Security

A

Mapping a host’s IP address to its link-layer address associated with peer’s hardware for direct delivery and sends messages through the underlying link-layer

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19
Q

Defenses against Address Resolution Spoofing

Network Security

A
  • Static ARP entities
  • Cache poisoning resistance
  • Monitor changes and report sus mappings
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20
Q

Describe

Defense to Address Resolution Spoofing: Static ARP Entities

Network Security

A

Ignores dynamic updates
Limitation: difficult to manage in a large system

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21
Q

Describe

Defense to Address Resolution Spoofing: Cache Poisoning Resistance

Network Security

A

Ignoring unsolicited ARP replies and updates based on timeouts
Limitations: susceptible to hijacking, timeouts have limited usefulness

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22
Q

Hijacking is the product of

Network Security

A

Sniffing and spoofing

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23
Q

Describe

Process of hijacking

Network Security

A

Once the attacker sniffs and spoof the necessary information, they are racing against the legit host to reply to the client’s request

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24
Q

Define

Rogue Gateway

Network Security

A

First hop for all Internet traffic

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25
What happens if an attacker gains control of a rogue gateway? | Network Security
Attacker can sniff, intercept, block, and modify traffic
26
# Define Broadcast Protocol | Network Security
Enables transmission of messages
26
Securing LAN Mechanisms | Network Security
* Do nothing and assume that it is secure * Smart switching/active monitoring
27
# Define Smart switching/active monitoring | Network Security
* Don't broadcast traffic * Forward Ethernet to the right path * Filter requests to limit listening/filtering replies to limit replying
28
# Define Dynamic Host Configuration Protocol | Network Security
Dynamically allocates the IP address to hosts of a network and provides information about DNS server, gateway, and period of lease
29
Threats against Dynamic Host Config Protocol | Network Security
* Fake DNS server => redirection of DNS lookups * Fake gateway router => interception of traffic, relay/modification of contents between host and remote machine
30
# Define Network Layer Attack | Network Security
Gaining access to a system that is isolated from other networks
31
What are the two types of Network Layer Attacks? | Network Security
IP Spoofing and Blind Spoofing
32
# Define IP Spoofing | Network Security
Impersonating sources of security-critical information to exploit address-based authentication
33
# Define Blind Spoofing | Network Security
Attacker sends IP packet and forges source IP with another host's IP => receiver sends a response back (unaccessible by attacker)
34
What are the two types of Internet spoofing? | Network Security
On-path and off-path spoofing
35
What can an on-path Internet spoofer do? | Network Security
See all traffic
36
What can an off-path Internet spoofer do? | Network Security
Has to blind spoof and guess header values/use brute force because they can't see traffic
37
# Define Autonomous System (AS) | Network Security
Network that manages its internal routing and is interconnected to form the Internet
38
What does an Autonomous System (AS) do? | Network Security
Determines where its packets should be sent
39
Who specifies the routing of an Automous System (AS)? | Network Security
Border Gateway Protocol
40
What makes blind-spoofing and IP spoofing possible? | Network Security
Lack of edge-AS restricting IP spoofing or blocking packets with a different source IP address
41
# Define User Datagram Protocol (UDP) | Network Security
Transport layer protocol that is connectionless, unreliable, best-effort datagram delivery service; best suited for multi-media and services based on requests
42
Cons of User Datagram Protocol (UDP) | Network Security
No delivery, integrity, ordering, or non-duplication guaranteed
43
What does User Datagram Protocol (UDP) introduce? | Network Security
Port abstraction
44
# Define Port abstraction | Network Security
One can communicate with different components of the same IP address
45
User Datagram Protocol (UDP) Packet components | Network Security
* Length * Destination port * Source port (optional) * Checksum (error detection, optional)
46
Types of User Datagram Protocol (UDP) Attacks | Network Security
* UDP Spoofing ~ IP Spoofing * UDP Hijacking ~ UDP Spoofing variant * UDP Port Scan - finding vulnerable/open ports * Denial of Service
47
# Define Transmission Control Protocol (TCP) | Network Security
Transport layer protocol that provides connection-oriented, reliable stream delivery service
48
Guarantees of a Transmission Control Protocol (TCP) | Network Security
Ordering, delivery, non-duplication
49
What are the ports associated with in UDP and TCP? | Network Security
OS Processes
50
Function of TCP | Network Security
Allows 2 hosts to establish a connection identified by IP address/ports of source and destination (socket)
51
# Describe TCP Window | Network Security
Performs flow control and is dynamic
52
# Describe TCP Packet | Network Security
Includes source/dest ports, seq #, ack #, data
53
# Define Sequence Number (Seq #) | Network Security
Relative position of TCP segment in stream
54
# Define Acknowledgement Number (ACK #) | Network Security
Position of next byte expected from stream
55
List TCP flags | Network Security
* SYN * ACK * FIN * RST * PSH
56
# Define TCP Flag: SYN | Network Security
Set only in the 1st packet to request sync of syn/ack nums and kickstart connection request
57
# Define TCP Flag: ACK | Network Security
Validates ACK # in all packets except 1st
58
# Define TCP Flag: FIN | Network Security
Indicates a request to terminate a stream in last packet from sender
59
# Define TCP Flag: RST | Network Security
Request to reset a connection
60
# Define TCP Flag: PSH | Network Security
Push buffered data request
61
List TCP Threats | Network Security
* Port Scan * Disruption * SYN Flooding
62
# Define TCP Threat: Port Scan | Network Security
Finds vulnerable/open ports
63
Types of TCP Port Scans | Network Security
* Normal * SYN * FIN
64
# Describe Port Scan: Normal | Network Security
Establish a connection with an arbitrary port and follows the TCP connection setup/shutdown (giveaway: lots of logs/connections)
65
# Describe Port Scan: SYN | Network Security
If a port is available, server/target will return an ACK packet (unavailable = RST packet) => scanner sends RST packet to "terminate" connection
66
Why is a SYN port scan not logged? | Network Security
A connection was never fully established
67
# Describe Port Scan: FIN | Network Security
Scanner sends a FIN packet to a host/target => open port: FIN ignored, closed port: RST
68
# Define TCP Threat: SYN Flooding | Network Security
Overload of connections
69
What does SYN Flooding cause? | Network Security
Denial of Service (DoS)
70
Defenses against SYN Flooding | Network Security
* Filtering * Small time-outs for 1/2 open connections * Limiting the number of 1/2 open connections * Recyling oldest 1/2 open connections * Requesting a SYN cookie to finish connection (set up and validate => reconstructed state)
71
Why can attackers spoof victim's IP and SYN Flood? | Network Security
ACK packets are not needed
72
# Describe TCP Threat: Disruption | Network Security
Abrupt termination request with RST packet and acceptance with correct seq #
73
Two Injections following TCP Disruption | Network Security
RST and Data Injection
74
# Define RST Injection | Network Security
MITM with port and sequence #
75
# Describe Data Injection | Network Security
Control hijacking with port and sequence #
76
Requirement to execute TCP Disruption | Network Security
TCP spoofing
77
How to guess the sequence number? | Network Security
Establish a legit connection with target and predict based on information
78
# Describe TCP Connection Setup Process | Network Security
1. Server listens to ports 2. Client sends requests (SYN packet) wtih initial sequence number (Sc) 3. Server accepts and responds (SYN-ACK packet) with initial sequence number (Ss) and ACK # (Sc + 1) 4. Client acknowledges with sequence number (Sc + 1) and acknowledgement number (Ss + 1) 5. Data is sent
79
# Describe TCP Connection Shutdown Process | Network Security
1. End A sends FIN packet (Sc) 2. End B replies with ACK packet (seq # = Ss, ACK # = Sc + 1) 3. End B sends FIN packet to close stream (seq # = Ss, ACK # = Sc + 1) 4. A replies with ACK packet (seq # = Sc + 1, ACK # = Ss + 2)
80
If a TCP segment is accepted, what's the order of the ack/seq/window? | Network Security
ACK # <= Seq # <= ACK # + Window

CSCI 4130 - Intro to Cybersecurity (11 decks)

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