There are many complex types of website attacks that are carried out by Technical or Semi Technical attackers. Some of these complex attacks include  DoS (Denial of Service) attacks and DDoS (Distributed Denial of Service) attacks.
I have implemented Firewall, still I am vulnerable?
Yes, It is possible to attack on server with DoS and DDoS attack even if you have implemented firewall.
I have DoS and DDoS attack application can I do attack on any system?
No, you should not try DoS and DDoS attack on server until and unless you have permission to do it. It is punishable act under cyber crime. IT Act 2000 has provision for DoS and DDoS attacks.
What is DoS and DDoS, How can I come to know that my Application is DDoSed?
In DoS and DDoS attack generally a single person or group of person try to compromise application vulnerability and by this way it will not let user to access website or web services.
How do they do it?
Following are some methods to compromise website, server or operating system.
- Send Massive Requests to website
- Router attacks
- Communication Channel
- Unauthorized code execution/ Instruction
- P2P file Sharing
Let’s understand each of them
1. Send Massive Requests to Website
Sending massive request to web site or web-server is also a type of DoS attack and if this attack is having multiple sources then it is called as DDoS. Due to increase in simultaneous request at a point of time web-server or website will stop responding to genuine users to access website.
In many cases we have seen crash or server, slowdown the server or shutdown of the server. Unless your server has capacity to handle such numerous requests, then security is breached and it will take long time to overcome from this damage.
Many times these attacks are done from intensive purpose from competitor, as people are buying limited bandwidth for website and by this trail your website will be out of bandwidth and people will not be able to access your portal.
I am a performance tester, and I do this practice. Am I a DoS attacker? Can anybody file case against me?
Yes, if you do not have written permission from your client to do application performance testing. If your client is using shared server then you should ask web hosting service provider as well.
2. Routers Attacks.
Attacker can attack on routers and eventually they can use router to destroy your website as well.
Frankly speaking I have not used this attack but one can use DoS attack to poison your routing records and it will redirect your request to another location.
One can implement IPS to prevent such kind of attacks on router. But remember IDS can detect attacks only if you have proper signature of the attack.
3. Communication Channel
Website will give you slow response when they have some upload or download configured. Attacker can user this technique to implement DoS or DDoS attack. One can start uploading large file and at the same time start downloading large file. During this period your server processor will do high processing and overall it may cause denial of service.
When file upload option is enable many servers do virus check as well and overall it will consume some process and give chance attacker to formalize a good attack.
4. Unauthorized code execution/ Instruction
This mechanism is made to confuse application security architecture or operating system. This may reset your application. Attackers are smart enough to inject code or re-sequence the application procedure. For example while heavy file is being uploaded attacker is sending command to delete the file. During this operation processor my stuck to 100%.
So, all DoS and DDoS attacks are limited to only servers. Is it true?
No, Any user who is connect to internet or network can be a victim of DoS or DDoS attack. Even network can be victim of DoS attack.
5. Peer to peer file sharing
Peer to Peer sharing websites or application can make you victim or source of DoS and DDoS attack. Applications like utorrent, if not configured properly can publish your details to another user while sharing contents.
Some more methods to attack on web application security and stopping user to access website involves
- Teardrop attacks,
- Degradation attacks,
- Nuke attacks,
- Reflected, or Distributed attacks,
- Permanent denial of service attacks.
