Network Security Flashcards
CIA Triad
Confidentiality
Integrity
Availability
Confidentiality
Keeping the data private & safe
(Encryption, Authentication to access resources)
Encryption ensures data can only be read (decoded) by intended recipient (Asymmetric/Symmetric)
Symmetric Encryption
Both sender & receiver use the same key
DES
Data Encryption Standard Developed mid-1970s 56-bit key Used by SNMPv3 Considered weak today
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, 256-bit
Asymmetric Encryption
Uses different keys for sender/receiver
RSA is most popular implementation
RSA commonly used with PKI (public key infrastructure)
PKI is used to encrypt data between web browser & shopping site
Can be used for secure emails
Sender/receiver use different keys to encrypt/decrypt
Integrity
Ensures data has not been modified in transit
Verifies the source the 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 & hash are sent to receiver
Receiver runs data received via same algorithm & obtains a hash
Two hashes are compared (if same, data not modified)
Hashing Algorithms
MD5 (Message Digest 5)
128-bit hash digest
SHA-1 (Secure Hash Algorithm 1)
160-bit hash digest
SHA-256 (Secure Hash Algorithm 256)
256-bit hash digest
CRAMMD5 (Challenge-response Authentication Mechanism MD5)
Common variant often used in email systems
Network Security Attack Types
Confidentiality:
Attempts to make data viewable by attacker
Integrity:
Attempts to alter data
Availability:
Attempts to limit network accessibility & usability
Confidentiality Attacks
Packet capture Wire tapping Dumpster diving Ping sweep Port scan Wireless interception EMI MITM Social Engineering
Integrity Attacks
MITM
Data diddling (changes data before storage)
Trust relationship exploitation
Salami attack (many small attacks = one big attack)
Password attack
Session Hijacking
Botnets
Availability Attacks
DoS/DDoS TCP SYN Flood Buffer overflow ICMP attacks (Smurf) UDP attacks (Fraggle) Ping of Death Electrical disturbances Physical environment attacks (Temperature, Humidity, Gas)
Protecting a Network
Physical controls User training Patching Vulnerability Scanners Honey pots & honey nets Remote-access security Security policies Incident response
Vulnerability Scanners
Ex: Nessus, Zenmap, Nmap
Periodically test network to verify that security components are behaving as expected & detect known vulnerabilities
Honey Pots/Nets
Systems designed as an attractive target
(Trap/Distraction)
Attackers waste resources
Honey pot = single machine
Honey net = network of multiple honey pots
Remote Access Security
SSH RADIUS (Open UDP-based auth protocol) TACACS+ (Cisco, TCP-based auth protocol) Kerberos (Windows domain auth protocol) 802.1X (Permits/dennies wired/wireless client access to LAN) 2FA SSO
BYOD Vulnerabilities
Bluejacking
Unauthorized messages over bluetooth
Bluesnarfing
Unauthorized access to wireless via bluetooth
Bluebugging
Unauthorized backdoor to connect bluetooth back to attacker
System Lifecycle
Conceptual Design Preliminary Design Detailed Design Production/Installation Operations/Support Phase Out Disposal
MFA
Multifactor Authentication
Something you know (user/pass)
Something you have (key fobs/smart cards)
Something you are (fingerprints/retina)
Something you do (signature, pattern, passphrase)
Somewhere you are (geotagging/geofencing)
Packet-Filtering Firewalls
Permits/denies traffic based on packet header
(Source/Destination IP)
(Source/Destination Port)