Network Security Flashcards
Network Security Fundamentals
▪ 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
Network Security Goals
Commonly called the CIA Triad
● Confidentiality
● Integrity
● Availability
Symmetric Encryption (Confidentiality)
▪ 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
Asymmetric Encryption (Confidentiality
▪ 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
Integrity
▪ 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
Hashing (Integrity)
▪ 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
Hashing Algorithms (Integrity)
▪ 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
Availability
▪ 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
Threat
▪ A person or event that has the potential for impacting a valuable
resource in a negative manner
Vulnerability
▪ 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
▪ Undesirable conditions or weaknesses that are in the general area
surrounding the building where a network is run
Technical Vulnerabilities
▪ 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)
Risk Management
The identification, evaluation, and prioritization of risks to minimize, monitor,
and control the vulnerability exploited by a threat
Risk Assessment
▪ A process that identifies potential hazards and analyzes what could
happen if a hazard occurs
● Security
● Business
Security Risk Assessment
Used to identify, assess, and implement key security controls within an
application, system, or network
o Penetration Test
Evaluates the security of an IT infrastructure by safely trying to exploit
vulnerabilities within the systems or network
Posture Assessment
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