Table of Contents
A Denial of Service attack is a malicious attempt to make a website or network unavailable by overwhelming it with traffic from a single source. The target of every Denial of Service (DOS) is to exhaust a network or website’s resources so that it becomes impossible for other users or services to access them.
How Does A Denial of Service Attack Work:
Denial-of-service works through the following mechanisms.
1) Flooding
2) Resource Exhaustion
3) Vulnerability Exploitation
4) Spoofing
Flooding:
Attackers send a large volume of traffic to the target in order to overwhelm its processing capabilities.
Resource Exhaustion:
This involves exhausting the target’s resources such as CPU, memory or network or website bandwidth with malicious traffic such that no resources are left for legitimate users.
Vulnerability Exploitation:
DoS attacks often exploit vulnerabilities in the target’s software, application or network configuration.
Spoofing:
Attackers may also use fake IP addresses to hide their origin, which makes it even more difficult to track the source of the attack.
Examples of DoS Attacks:
The examples are:
1) ICMP Flood
2) HTTP Flood
3) Teardrop Attack
4) Slowloris
ICMP Flood:
This involves overloading a target with Internet Control Message packets (ICMP).
HTTP Flood:
This is done by sending numerous HTTP requests to a web server in order to overwhelm resources.
Teardrop Attack:
Teardrop attack involves sending fragmented packets with overlapping fragments, which can cause a system to crash.
Slowloris:
This is the procedure of attacking a web server by sending incomplete HTTP requests, leaving it open and vulnerable to attacks.
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What is a Denial of Service Attack (DoS)?
A Denial of Service is a cyberattack that is targeted at making a computer or network resource unavailable to legitimate users by flooding or overwhelming it with continuous traffic or resource requests.
The attack is achieved by sending massive and excessive traffic in a bid to overwhelm the target’s ability to handle requests and effectively shutting down services.
Types of Denial of Service Attacks:
The following are types of DoS attacks:
1) Volumetric Attacks
2) Application Layer Attacks
3) Network Layer Attacks
Volumetric Attacks:
These attacks mostly focus on overwhelming the target with a large volume of traffic, irrespective of the content.
Application Layer Attacks:
Application layer attacks are directed at the application layer of the network, often exploiting vulnerabilities in specific applications.
Network Layer Attacks:
These attacks target the network layer using techniques such as ICMP flooding.
Consequences of DoS Attacks:
1) Website Outages
2) Business Disruptions
3) Reputational Damage
Website Outages
A Denial of Service attack often causes website outages and hence makes a website or online service unavailable to users.
Business Disruptions:
Businesses who mostly rely on online services to transact business may suffer significant disruptions and financial losses.
Reputational Damage:
Denial of Service attacks can damage a company’s reputation and erode company trust.
This is most likely going to negatively affect business.
Protecting Against Denial of Service Attack:
There are several methods to guard against DoS attacks, such as:
1):Use of Firewall
2) Intrusion Detection/Prevention Systems (IDS/IPS)
3) Load Balancers
4) Content Delivery Networks (CDN)
5) Blacklisting IP Addresses
6) Rate Limit
Use of Firewall:
Firewall use is very effective in filtering out malicious traffic and preventing it from reaching the target.
Intrusion Detection/Prevention Systems (IDS/IPS):
IDS/IPS systems have the capability to detect and block DoS attacks.
Load Balancers
Load balancers are systems that distribute traffic across multiple servers, which makes the target less vulnerable to attacks.
Content Delivery Networks (CDNs):
CDNs can store content closer to users and thus reduce the impact of a Denial of Service attack. CDN uses regionally designated servers to deliver content to users based on their geographical locations.
Blacklisting IP addresses:
Blacklisting IP addresses associated with known DoS attacks is a very effective way to guard against attacks.
Rate Limiting:
The number of requests made by a user or IP address at a particular time can be limited to guard against DoS attacks.
Limiting the number of requests a user or IP address can make in a certain period can prevent DoS attacks.
What is the difference between Denial-of-service (DoS) and Distributed Denial of Service Attack (DDoS)?
A DDoS attack is a more complex form of Denial of Service attack that uses multiple sources, and sometimes a botnet of compromised devices, to launch the attack.
Key Differences between DoS and DDoS attacks:
1) Attack Source:
DoS uses a single attack source while DDoS uses multiple attack sources.
2) Complexity:
DoS attacks are simpler to implement, while DDoS attacks are more difficult and complex to implement.
3) Impact:
A Denial of Service attack can be disruptive to some extent, while DDoS attacks can cause more significant and prolonged downtime.
4) Detection and Mitigation:
DoS is easier to detect and block because the attack comes from a single source, while DDoS is more difficult to mitigate because the attacks come from multiple sources.
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Comparison between DoS and DDoS attacks:
This comparison is based on the following parameters.
a) Source b) Comparison c) Impact
DoS Attack:
Source:
Denial of Service attack uses a single source such as a computer.
Complexity:
DoS is simpler to implement and easier to mitigate.
Impact:
It can sometimes be disruptive, but the damage is typically less severe and easier to resolve than a DDoS attack.
Examples of a DoS attack:
A user floods a website with repeated requests and causes it to crash.
DDoS Attack
Source:
DDoS attacks use multiple sources, often a botnet of compromised devices and applications.
Complexity:
DDoS attacks are more complex and challenging to detect and mitigate than DoS attacks.
Impact:
DDoS attacks are very disruptive and more severe than Denial of Service attacks. It can cause significant and prolonged downtime due to the large volume of overwhelming traffic.
Example: A botnet of thousands of infected computers floods a website with traffic, making it inaccessible.
In conclusion, a DDoS attack is a more powerful and sophisticated version of a DoS attack that mostly leverages multiple sources to overwhelm a target and cause wide-ranging disruption.