Your Quick Guide to Common Attacks

Your Quick Guide to Common Attacks

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Denial of Service (DOS/DDOS)

  • A denial of service attack is any attack used to achieve the disruption of any service to legitimate users
  • DDOS is the ‘distributed’ form of such an attack where many ‘Zombies’ that have been taken over by hackers launch simultaneous attacks to achieve a more effective denial of service attack

Back Door

  • Any opening left in a functional piece of software that allows ‘unknown’ entry into the system / or application without the owners knowledge.
  • Many times, back doors are left in by the software creators


  • Spoofing is a technique used to gain unauthorized access to computers
  • A hacker must first find an IP address of a trusted host
  • Once this information is gotten, then the hacker can use this information to make the recipient think that the hacker is the trusted sender
  • Please use the link I provided to investigate spoofing deeper. It is very important that you fully understand it

Man in the Middle

  • A Man in the Middle attack is when an attacker is able to intercept traffic by placing themselves in the middle of the conversation.
  • Man in the Middle attacks involve a malicious attacker intercepting communications and fooling both parties into believing they are communicating with each other when they are really being watched
  • The attacker can then do anything to the transmission they are now apart of to include eavesdropping or planting information
  • Wireless systems are very susceptible to this form of attack.


  • A Replay attack is when a Hacker uses a Sniffer to grab packets off the wire
  • After packets are captured, then the hacker can simply extract information from the packets like authentication information and passwords
  • Once the information is extracted, the captured data can be placed back on the network or replayed

TCP/IP Hijacking

  • This is also called “Session Hijacking”
  • A hacker can take over a TCP session between two machines
  • A popular method is using source-routed IP packets

DNS Poisoning

  • DNS Poisoning is when your DNS files are poisoned with bad information
  • In other words, if you have an A record that points to a trusted host, a hacker can change it and point you in the wrong direction for malicious intent

Weak Keys

  • Weak keys are secret keys with a certain value for which the block cipher in question will exhibit certain regularities in encryption or, in other cases, a poor level of encryption


  • Mathematical  (or Algebraic) attacks are a class of techniques that rely for their success on block ciphers exhibiting a high degree of mathematical structure

Social Engineering

  • Most times hackers try to attack the actual ‘systems’ to exploit their weaknesses
  • Another form of attack is to exploit ‘end user’ weakness
  • Exploiting the weakness of human nature to get someone to hand over their credentials to you from either peer pressure or trickery


  • A birthday attack is a name used to refer to a class of brute-force attacks
  • Please use the link provided to research this deeper. You have to understand hash functions and password cracking to fully understand this and the link provided will do that

Password Guessing

  • Password Guessing or ‘cracking’ is the attack on authentication credentials for any given system

Brute Force

  • A form of Password Cracking
  • Brute Force attacks will try every single key combination known to crack your password.
  • The only protection against them is to either have a key length too long to crack anytime in this lifetime, or change the password frequently.


  • A form of Password Cracking
  • The term ‘dictionary’ comes from the actual book of known words… this is transferred into a file and loaded into a tool to try to help a hacker to crack your password
  • The defense against this is to not use simple to guess and known dictionary words as passwords

Software Exploitation

  • Attacks against a systems bugs or flawed code
  • Use Hot Fixes and Service packs to fix them

War Dialing

  • The process of running modem scanning tools against a PBX or any given dialup modem for the purpose of penetration.
  • A war dialer is a computer program used to identify the phone numbers that can successfully make a connection with a computer modem.
  • The program will dial a range of numbers you ask it to dial and will log failure and success ranges in a database

War Driving

  • The process of using an attack tool to penetrate wireless systems from outside the facility where the wireless system sits
  • A wireless Ethernet card set to work in promiscuous mode is needed to War drive, and you will also need a powerful antenna if you are going to remain at a distance

Buffer Overflow

  • Buffer Overflow attacks take advantage of poorly written code
  • If the code will not check the length of variable arguments then it can be susceptible to this kind of attack

SYN flood

  • SYN Flood attacks exploit the three-way handshaking mechanism of the TCP/IP protocol
  • A large number of half-opened connections is used to deny access to legitimate requestors


  • Exploits ICMP
  • Performed by transmitting an echo request packet to a network’s broadcast address with a spoofed source address
  • The victim is then quickly overwhelmed by a large number of echo replies


  • Sniffing attacks use protocol analyzers to capture network traffic for password and other data capture

Ping of Death

  • Used to attempt to crash your system by sending oversized packets to a host
  • Ping of death can actually be run from older versions of Windows, Linux and Cisco routers.
  • At a Windows command line, simply type:

     ping -l 65550 192.168.1.X

  • At a Linux command line, simply type:

     ping -s 65550 192.168.1.X

Port Scanning

  • Port Scanning is performed by running a vulnerability scanner on a system to see what open ports are open
  • The second have of the attack is to then exploit whatever you find via other attacks


  • A flaw with TCP port 19 where if you connect via the port
  • You can run what’s called a Character Generator attack

Fragment Attack

  • An exploit that targets IP fragmentation and reassembly code are common
  • Numerous attacks have been performed upon the premise of overlapping fragments
  • Attacks include:

    • Teardrop
    • Teardrop2
    • NewTear
    • SynDrop
    • Bonk
    • Boink

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