What is Dos Attack ?
A denial-of-service or Dos attack is a malicious attempt to overwhelm a web property with traffic in order to disrupt it’s normal operations. Dos attacks typically function by overwhelming or flooding a target machine with requests until normal traffic is unable to be process, thus resulting in denial-of-service to additional users.
While an attack that crashes a server can often be deal with successfully by simply rebooting the system. so, flooding attacks can be more difficult to recover from recovering from a distributed denial-of-service(DDoS) attack in which attack traffic comes from a large number of sources, and can be even more difficult.
Types of Dos Attack
1. Application-layer Flood
In this attack, an attacker simply floods the service with requests from a spoofed IP address in an attempt to slow or crash the service, illustrated in . This could take the form of millions of requests per second or a few thousand requests to a particularly resource-intensive service that eat up resources until the service is unable to continue processing the requests.
2. DDoS Attack
Distributed Denial of Service (DDoS) attacks occur in much the same way as DoS attacks expect that requests are send from many clients as opposed to just one, illustrated in DDoS attacks often involve many machines that works like zombie machines then send massive amounts of requests to a service to disable it. DDoS attacks are famously hard to mitigate, which is why outsourcing network filtering to a third party is the recommended approach.
3. Unintended Denial of Service Attacks
however, This type of attack is unintend Denial of Service attack. so, The canonical example of an unintend DDoS is refer The Slashdot is an internet news site where anyone can post news stories and link to other sites. If a linked story becomes popular, it thus can cause millions of users to visit the site overloading the site requests. If the site is not build to handle that kind of load, the increased traffic can slow or even crash the linked site.
4. Fragmentation attacks
therefore, This is an attack that fights against the reassembling ability of the target. Numerous fragmented packets are sent to the target, thus making it difficult for the target to reassemble them thereby denying access to the valid clients
5. TCP-State exhaustion
The attacker sets up and tears down TCP connections and overwhelms the stable tables; thereby, causing a DOS attack.
6. Plashing
This is done by causing permanent damage to the system hardware thereby making them completely unusable. The only solution is to re-install the hardware.
How to prevent this Attack ?
Stopping Dos attack, with dotDefender web application firewall you can avoid Dos attacks because dotDefender inspects your HTTP traffic and checks their packets against rules such as to allow or deny protocols, ports, or IP addresses to stop web applications from being exploited.
The reasons dotDefender offers such a comprehensive solution to your web application security needs are:
- Easy installation on Apache and IIS servers.
- Strong security against known and emerging hacking attacks.
- Best-of-breed predefined security rules for instant protection..
- interface and API for managing multiple servers with ease.
- Requires no additional hardware, and easily scales with your business.
How does an attacker launch a Denial of Service attack?
There are many different ways that an attacker can launch a denial of service attack. some of ways given below
- Buffer overflows in the application functions.
- Malformed data to raise unexpected exceptions.
- Exploited race conditions in multi-threaded systems.
- Heavy-duty SQL queries via web forms and “spamming” them with request, e.g., inserting % characters within query fields.
- SQL injection attacks executing recursive CPU-intensive queries.
- The end user web browser to overload the application with parallel requests via persistent/reflected Cross-site scripting attacks.
- Overly-Complex regular expressions within search queries.
- Excessively large files uploaded to the server.
Protect Yourself from Denial of Service Attack
Dotdefender’s unique security approach eliminates the need to learn the specific threats that exist on each web application. The Software that runs dotDefender focuses on analyzing the request and the impact it has on the application. Effective web application security is based on three powerful web application security engines:
Pattern Recognition, Session Protection and Signature Knowledgebase.
The Pattern recognition web application security engine employed by dotDefender effectively protects against malicious behavior such as denial of service attacks. The patterns are regular expression-based and designed to efficiently and accurately identify a wide array of application-level attack methods. As a result, dotDefender is characterized by an extremely low same end result as a well coordinated DoS threat.
What sets dotDefender apart is that it offers comprehensive protection against Denial of Service and other attacks while being one of the easiest solutions to use.
In just 10 clicks, a web administrator with no security training can have dotDefender up and running. Its predefined rule set offers out of the box protection that can be easily managed through a browser based interface with virtually no impact on your server or web site’s performance.
Written By: Abhishek Kumar
Reviewed By: Sayan Chatterjee
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