Dos Attack
DOS attack (denial of
service attack)is a type of attack on a network that is designed to bring the
network to its knees by flooding it with useless traffic and an attempt to make
a machine or network resource unavailable to its intended users. It consists of the efforts of one or more people
to temporarily or indefinitely interrupt or suspend services of a host
connected to the internet.
There are most
important types of DOS attacks below :
1.
Flood
Attack :- Flood attacks are the first known form of a DOS attack. The mechanism
of a flood attack is simple attackers send more traffic to a server than it can
handle. It the bandwidth of the victim is good, a flood attack has a chance to
succeed only if it is a DDOS. Even if a webmaster adds more bandwidth, this
still is not a sufficient protection against a flood attack. However, if the
bandwidth is insufficient, even the normal volume of legitimate requests can
look like a flood attack. Sometimes when a site gets traffic from popular
sites, for ex. The front page of Digg, this could look like a DDOS attack but
actually this is really legitimate traffic.
2.
Buffer
Overflow Attack :- Most commonly used DOS attack, can be performed locally or
remotely. Most commonly used attack method is using a vulnerable application of
program. Result of compromise on security of network. Common modes of attacks
are misuse of internal resources and altering configuration.
3.
Ping of
Death :- In this type of attack an attacker deliberately sends an ICMO echo
packet of more than 65536 bytes. IP Packet with size of 65536 bytes is
oversized packet for TCP/IP stack. Many Operating System don’t know how to
response to such huge packet resulting in freezing or crashing down, Attack
mode can be classified as altering of configuration and misuse of resources.
4.
Smurf
Attack :- The Smurf attack is one more way to paralyze a network, this time
from the inside. The mechanism of a Smurf attack is more sophisticated and the
critical part is to discover a broadcast server. When a hacker knows the broadcast
servers in a network, he or she sends a ping request. The source IP address in
this ping request is fake and it looks as if looks as if the ping comes from
inside the network. When the broadcast server receives the ping request, the
ping request is sent to the entire network and all the machines in the network
return a response. These responses are further redirected by the broadcast
server to the target machine. Smurf attacks are more difficult to defend
against but still if a network is well planned and properly maintained, their
effect shouldn’t be a devastating one.
5.
Teardrop
Attack :- This attack takes advantage of fragmentation of IP packets during
transmission. A large packet is chopped in pieces for easy transmission with
each having sequence number in offset so that when all chucks get received they
can be easily combined. In tear drop attack an attacker manipulates the offset
value of the second or later fragment to overlap with previous or next one,
This attack may cause hang and crash of system. Mode of attack is altering
configuration.
6.
SYN Attack
:- SYB attacks also exploit a weakness in the TCP/IP protocol. When a
connection is established via TCP/IP, this involves a handshaking mechanism,
which consists of the exchange of SYN and ACK messages. When a hacker floods
the receiving system with SYN messages, this fills the SYN buffer. In this case
the receiving party can’t send an ACK message and no TCP/IP connections with
any hosts are possible.
How To Protect From A DOS Attack (denial of service attack) :-
With dotDenfender web
application firewall you can avoid DOS attacks because dotDefender inspects
your HTTP traffic and check their packets against rules such as to allow or
deny protocols, ports or IP addresses to stop web applications from being
exploited. Architected as plug and play software, dotDefender provides optimal
out of the box protection against DOS threats, cross site scripting, SQL
Injection attacks, path traversal and many other web attack techniques. So
dotDefender is the simple solution to protect you from DOS attacks.
