Understanding DDOS Attack

kapil sharma
Dec 31, 2017 · 3 min read

Distributed Denial of service attack (Dos attack) is a cyber-attack where the attacker make server machine so busy/hung that it stop responding to other user. Most of the users will start seeing some error message(like not available or not responding).

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Types of DOS Attack

UDP Flood

SYN Flood

  • First, a “synchronize”, or SYN message, is sent to the host machine to start the conversation.
  • Next, the request is “acknowledged” by the server. It sends an ACK flag to the machine that started the “handshake” process and awaits for the connection to be closed.
  • The connection is completed when the requesting machine closes the connection.

A SYN flood attack will send repeated spoofed requests from a variety of sources at a target server. The server will respond with an ACK packet to complete the TCP connection, but instead of closing the connection the connection is allowed to timeout. Eventually, and with a strong enough attack, the host resources will be exhausted and the server will go offline.

Ping of Death

Note: This was a real problem in early years (think 1996), but doesn’t have the same effect these days. Most ISPs block ICMP or “ping” messages at the firewall. However, there are many others forms of this attack that target unique hardware or applications. Some other names are “Teardrop”, “Bonk”, and “Boink”.

Reflected Attack

Application Level Attacks

Degradation of Service Attacks

Few other type of attacks are:

- Peer-to-Peer Attacks
- Nuke
- Slowloris
- Unintentional DDoS

Which security measures to take

2. Use secure hosting like Heroku platform with multiple out-of-the box security features.

3. Install web application firewall. WAFs like the one by Wallarm generate security rules and verify the impact of malicious payloads in real time. Although make sure it doesn’t impose excessive rules.

4. Look after your code.

5. Keep an eye on your website. Track any changes on your web pages, their size and content changes.

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