Hãçkêrs Beginners Basics

Summary

A denial of service attack’s intent is to deny legitimate users access to a resource such as a network, server etc.

There are two types of attacks, denial of service and distributed denial of service.

A denial of service attack can be carried out using SYN Flooding, Ping of Death, Teardrop, Smurf or buffer overflow

Security patches for operating systems, router configuration, firewalls and intrusion detection systems can be used to protect against denial of service attacks.

Enter the target IP address, in this example; we have used the target IP we used in the above example.
HERE,

0 as the number of packets means infinity. You can set it to the desired number if you do not want to send, infinity data packets

The size field specifies the data bytes to be sent and the delay specifies the time interval in milliseconds.

Click on send button
You should be able to see the following results

the attack is successful, you should be able to see increased network activities.

Flooding the target computer with data packets doesn’t have much effect on the victim. In order for the attack to be more effective, you should attack the target computer with pings from more than one computer.
The above attack can be used to attacker routers, web servers etc.
If you want to see the effects of the attack on the target computer, you can open the task manager and view the network activities.

Right click on the taskbar

Select start task manager

Click on the network tab

You will get results similar to the following

HERE,

“ping” sends the data packets to the victim

“10.128.131.108” is the IP address of the victim

“-t” means the data packets should be sent until the program is stopped

“-l” specifies the data load to be sent to the victim

You will get results similar to the ones shown below

For this example, we are using Mobile Broadband connection details. Take note of the IP address. Note: for this example to be more effective, and you must use a LAN network.
Switch to the computer that you want to use for the attack and open the command prompt
We will ping our victim computer with infinite data packets of 65500
Enter the following command

ping 10.128.131.108 –t |65500

Hacking Activity: Ping of Death

We will assume you are using Windows for this exercise. We will also assume that you have at least two computers that are on the same network. DOS attacks are illegal on networks that you are not authorized to do so. This is why you will need to setup your own network for this exercise.
Open the command prompt on the target computer
Enter the command ipconfig. You will get results similar to the ones shown below

DoS Protection: Prevent an attack

An organization can adopt the following policy to protect itself against Denial of Service attacks.

Attacks such as SYN flooding take advantage of bugs in the operating system. Installing security patches can help reduce the chances of such attacks.

Intrusion detection systems can also be used to identify and even stop illegal activities

Firewalls can be used to stop simple DoS attacks by blocking all traffic coming from an attacker by identifying his IP.

Routers can be configured via the Access Control List to limit access to the network and drop suspected illegal traffic.

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Smurf
This type of attack uses large amounts of Internet Control Message Protocol (ICMP) ping traffic target at an Internet Broadcast Address. The reply IP address is spoofed to that of the intended victim. All the replies are sent to the victim instead of the IP used for the pings. Since a single Internet Broadcast Address can support a maximum of 255 hosts, a smurf attack amplifies a single ping 255 times. The effect of this is slowing down the network to a point where it is impossible to use it.

Buffer overflow
A buffer is a temporal storage location in RAM that is used to hold data so that the CPU can manipulate it before writing it back to the disc. Buffers have a size limit. This type of attack loads the buffer with more data that it can hold. This causes the buffer to overflow and corrupt the data it holds. An example of a buffer overflow is sending emails with file names that have 256 characters.

Teardrop
This type of attack uses larger data packets. TCP/IP breaks them into fragments that are assembled on the receiving host. The attacker manipulates the packets as they are sent so that they overlap each other. This can cause the intended victim to crash as it tries to re-assemble the packets.

SYN attack
SYN is a short form for Synchronize. This type of attack takes advantage of the three-way handshake to establish communication using TCP. SYN attack works by flooding the victim with incomplete SYN messages. This causes the victim machine to allocate memory resources that are never used and deny access to legitimate users.