Availability Attacks

Availability Attacks

• Availability Attacks
  • Availability Attacks
  • Availability attack methods
    • Denial of Service (DoS)
    • Distributed Denial of Service (DDoS)
    • TCP SYN Flood
    • Buffer Overflow

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Availability Attacks

• attempt to limit the accessibility and usability of a system.
• Availability attacks vary widely,
  • consume the processor or memory resources on a target system, that system might be unavailable to legitimate users.
• doing physical damage to that system.

Availability attack methods

Denial of Service (DoS)

• sending the target system a flood of data or requests that consume the target system’s resources.
• some operating systems (OS) and applications might crash when they receive specific strings of improperly formatted data,
• attacker could leverage such OS/application vulnerabilities to render a system/ application inoperable.
• The attacker often uses IP spoofing to conceal his identity when launching a DoS attack.

Distributed Denial of Service (DDoS)

• DDoS attacks can increase the amount of traffic flooded to a target system.
• an attacker compromises multiple systems (zombies), which can be instructed by attacker to simultaneously launch a DDoS attack against a target system.

TCP SYN Flood

• One variant of a DoS attack
• the attack can send multiple SYN segments to a target system with false source IP addresses in the header of the SYN segments.
• Can never complete the three-way TCP handshake.
• Because many servers limit the number of TCP sessions they can have open simultaneously,
• a SYN flood can render a target system incapable, can not open a TCP session with a legitimate user.

Buffer Overflow

• Buffer: a area of memory, a computer program that has been given a dedicated area of memory to which it can write.
• Buffer overflow: a program attempts to write more information than the buffer can accommodate.
  • Injects code written by a malicious user into a running app.
  • Exploiting the common programming error of not checking whether an input string read by the app is larger than buffer (the variable into which it is stored).
• If permitted to do so, the program can fill up its buffer and then have its output spill over into the memory area being used for a different program.
• This could potentially cause the other program to crash.
• Some programs are known to have this vulnerability (the characteristic of overrunning their memory buffers) and can be exploited by attackers.