Network Security Flashcards

1
Q

Network Security Fundamentals

A

▪ Networks are increasingly dependent on interconnecting with other
networks
▪ Risks exist not just on the untrusted Internet, but also inside our own
organization’s networks and must be minimized or eliminated
▪ Understanding the various threats facing our networks is important in
order to best defend the network against the onslaught of cyber-attacks
they are constantly facing

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2
Q

Network Security Goals

A

Commonly called the CIA Triad
● Confidentiality
● Integrity
● Availability

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3
Q

Symmetric Encryption (Confidentiality)

A

▪ Both sender and receiver use the same key
▪ DES (Data Encryption Standard)
● Developed in the mid-1970s
● 56-bit key
● Used by SNMPv3
3DES (Triple DES)
● Uses three 56-bit keys (168-bit total)
● Encrypt, decrypt, encrypt
▪ AES (Advanced Encryption Standard)
● Preferred symmetric encryption standard
● Used by WPA2
● Available in 128-bit, 192-bit, and 256-bit keys
▪ Sender and receiver use the same key to encrypt and decrypt the
messages

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4
Q

Asymmetric Encryption (Confidentiality

A

▪ Uses different keys for sender and receiver
▪ RSA is the most popular implementation
▪ RSA algorithm is commonly used with a public key infrastructure (PKI)
▪ PKI is used to encrypt data between your web browser and a shopping
website
▪ Can be used to securely exchange emails
▪ Sender and receiver use different keys to encrypt and decrypt the
messages

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5
Q

Integrity

A

▪ Ensures data has not been modified in transit
▪ Verifies the source that traffic originates from
▪ Integrity violations
● Defacing a corporate web page
● Altering an e-commerce transaction
● Modifying electronically stored financial records

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6
Q

Hashing (Integrity)

A

▪ Sender runs string of data through algorithm
● Result is a hash or hash digest
▪ Data and its hash are sent to receiver
▪ Receiver runs data received through the same algorithm and obtains a
hash
▪ Two hashes are compared
● If the same, the data was not modified

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7
Q

Hashing Algorithms (Integrity)

A

▪ Message digest 5 (MD5)
● 128-bit hash digest
▪ Secure Hash Algorithm 1 (SHA-1)
● 160-bit hash digest
▪ Secure Hash Algorithm 256 (SHA-256)
● 256-bit hash digest
▪ Challenge-Response Authentication Mechanism Message Digest 5
(CRAMMD5)
● Common variant often used in e-mail systems

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8
Q

Availability

A

▪ Measures accessibility of the data
▪ Increased by designing redundant networks
▪ Compromised by
● Crashing a router or switch by sending improperly formatted data
● Flooding a network with so much traffic that legitimate requests
cannot be processed
o Denial of Service (DoS)
o Distributed Denial of Service

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9
Q

Threat

A

▪ A person or event that has the potential for impacting a valuable
resource in a negative manner

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10
Q

Vulnerability

A

▪ A quality or characteristic within a given
resource or its environment that might
allow the threat to be realized
● Internal Threat
o Any threat that originates
within the organization
itself
● External Threat
o Any threat that could be
people, like a hacker, or it
can be an event or
environmental condition

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11
Q
A

▪ Undesirable conditions or weaknesses that are in the general area
surrounding the building where a network is run

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12
Q

Technical Vulnerabilities

A

▪ System-specific conditions that create security weaknesses
● Common Vulnerabilities and Exposures (CVE)
o A list of publicly disclosed computer security weaknesses
● Zero-Day Vulnerability
o Any weakness in the system design, implementation,
software code, or a lack of preventive mechanisms in place
▪ CVEs (Known vulnerabilities)
▪ Zero-Day (Brand new vulnerability)

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13
Q

Risk Management

A

The identification, evaluation, and prioritization of risks to minimize, monitor,
and control the vulnerability exploited by a threat

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14
Q

Risk Assessment

A

▪ A process that identifies potential hazards and analyzes what could
happen if a hazard occurs
● Security
● Business

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15
Q

Security Risk Assessment

A

Used to identify, assess, and implement key security controls within an
application, system, or network

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16
Q

o Penetration Test

A

Evaluates the security of an IT infrastructure by safely trying to exploit
vulnerabilities within the systems or network

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17
Q

Posture Assessment

A

Assesses cyber risk posture and exposure to threats caused by
misconfigurations and patching delays
● Define mission-critical components
● Identify strengths, weaknesses, and security issues
● Stay in control
● Strengthen position

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18
Q

Security Principles
o Least Privilege

A

Using the lowest level of permissions or privileges needed in order to
complete a job function or admin task

19
Q

Discretionary Access Control (DAC)

A

An access control method where access is determined by the
owner of the resource
o Every object in a system has to have an owner
o Each owner must determine the access rights and
permissions for each object

20
Q

Mandatory Access Control (MAC)

A

An access control policy where the computer system gets to
decide who gets access to what objects
o Unclassified
Confidential
o Secret
o Top secret

21
Q

Role-Based Access Control (RBAC)

A

An access model that is controlled by the system but focuses on a set of
permissions versus an individual’s permissions
▪ Creating groups makes it easy to control permissions based around actual
job functions

22
Q

Zero-Trus

A

▪ A security framework that requires users to be authenticated and
authorized before being granted access to applications and data
1. Reexamine all default access controls
2. Employ a variety of prevention
techniques and defense in depth
3. Enable real-time monitoring and
controls to identify and stop
malicious activity quickly
4. Ensure the network’s zero-trust
architecture aligns to a broader
security strategy

23
Q

DMZ

A

A perimeter network that protects an organization’s internal local area
network from untrusted traffic

24
Q

Screen Subnet

A

Subnet in the network architecture that uses a single firewall with three
interfaces to connect three dissimilar networks
● Triple-homed firewall

25
Separation of Duties
Prevent frauds and abuse by distributing various tasks and approval authorities across a number of different users
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Honeypot/ Honeynet
Attracts and traps potential attackers to counteract any attempts at unauthorized access to a network ▪ Think vertical through the layers as well as horizontal or lateral across the network using screen subnets
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Multifactor Authentication
o Authenticates or proves an identity using more than one method ▪ Something you know ▪ Something you have ▪ Something you are ▪ Something you do ▪ Somewhere you are
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Dictionary Attack
▪ Guesses the password by attempting to check every single word or phrase contained within a word list, called a dictionary ● Do not use anything that looks like a regular word
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Brute Force Attack
Tries every possible combination until they figure out the password ● Use a longer and more complicated password o Uppercase o Lowercase o Numbers o Special characters ● For good security, use a minimum of 12 characters
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Local Authentication
Process of determining whether someone or something is who or what it ● Claims itself to be ● Simplified version of X.500
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Lightweight Directory Access Protocol (LDAP)
▪ Validates a username and password combination against an LDAP server as a form of authentication ● Port 389 LDAP ● Port 636 LDAP Secure
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o Active Directory (AD)
Organizes and manages everything on the network, including clients, servers, devices, and users
33
Kerberos
▪ Focused on authentication and authorization within a Windows domain environment ▪ Provides secure authentication over an insecure network
34
Remote Authentication Dial-In User Service (RADIUS)
Provides centralized administration of dial-up, VPN, and wireless network authentication ● Authentication ● Authorization ● Accounting o Commonly uses: ▪ Port 1812 Authentication messages ▪ Port 1813 Accounting messages o Proprietary versions of RADIUS may also use: ▪ Port 1645 Authentication messages ▪ Port 1646 Accounting message
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o Terminal Access Controller Access Control System Plus (TACACS+)
Used to perform the role of an authenticator in an 802.1x network ● RADIUS (UDP) ● TACACS+ (TCP) ● Ensure Port 49 is open ● Excellent if using Cisco devices
36
802.1x
▪ A standardized framework that’s used for port-based authentication on both wired and wireless networks ● Supplicant ● Authenticator ● Authentication server
37
Extensible Authentication Protocol (EAP)
Allows for numerous different mechanisms of authentication ● EAP-MD5 o Utilizes simple passwords and the challenge handshake authentication process to provide remote access authentication ● EAP-TLS o Uses public key infrastructure with a digital certificate being installed on both the client and the server ● EAP-TTLS o Requires a digital certificate on the server and a password on the client for its authentication ● EAP Flexible Authentication via Secure Tunneling (EAP-FAST) o Uses a protected access credential to establish mutual authentication between devices ● Protected EAP (PEAP) o Uses server certificates and Microsoft’s Active Directory databases to authenticate a client’s password ● Lightweight EAP (LEAP) o A proprietary protocol that only works on Cisco-based devices
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● Network Access Control (NAC)
o Ensures a device is scanned to determine its current state of security prior to being allowed network access
39
o Persistent Agent
A piece of software installed on a device requesting access to the network
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Non-Persistent Agent
Requires the users to connect to the network and go to a web-based captive portal to download an agent onto their devices
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IEEE 802.1x
Used in port-based Network Access Control ● Time-based o Defines access periods for given hosts on using a timebased schedule ● Location-based o Evaluates the location of the endpoint requesting access using IP or GPS geolocation ● Role-Based (Adaptive NAC) o Reevaluates a device’s authentication when it’s being used to do something ● Rule-based o Uses a complex admission policy that might enforce a series of rules with the use of logical statements
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Physical Security o Detection Methods
▪ Security control used during an event to find out whether or not something malicious may have happened ● Wired o Allows the device to be physically cabled from its camera all the way to a central monitoring station ● Wireless o Easier to install, but they can interfere with other wireless systems, like 802.11 wireless networks
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Network Security Attacks
▪ Our security goals (CIA) are subject to attack ▪ Confidentiality attack ● Attempts to make data viewable by an attacker ▪ Integrity attack ● Attempts to alter data ▪ Availability attack ● Attempts to limit network accessibility and usability
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