Denial of Service (DoS)

• Used to describe an attack that attempts to make a computer or server’s resources unavailable

Flood Attacks

Ping Flood

• Overloading a server with ICMP echo requests (pings)
• Often countered by blocking echo replies

SYN Flood

• Initiating multiple TCP sessions but not completing the 3-way handshake
• Consumes server resources and prevents legitimate connections
• Countermeasures:
  • Flood guard
  • Timeout configurations
  • Intrusion prevention systems

Permanent Denial of Service (PDOS) Attack

• Exploits security flaws to break a networking device permanently by re-flashing its firmware
• Requires a full firmware reload to bring the device back online

Fork Bomb

• Attack creates a large number of processes, consuming processing power
• Not considered a worm, as it doesn’t infect programs or use the network
• Self-replicating nature causes a denial of service condition

Distributed Denial of Service (DDoS) Attack

• Malicious attempt to disrupt the normal functioning of a network, service, or website by overwhelming it with a flood of internet traffic
• Involves multiple machines attacking a single server simultaneously