A denial-of-service (DoS) attack is a type of cyber attack which aims to make a system or service inaccessible to its intended users. This is typically done by overwhelming the target machine or network with a flood of unnecessary requests which disrupt the normal traffic.

For example, a Syn Flood attack bombards the server with connection requests, while a Smurf Attack uses spoofed packets to overload the network. Another notorious method is the Ping of Death, which exploits vulnerabilities to crash the system. DoS attacks often target web servers or online services, making them unavailable to access for legitimate users. Different forms of DoS attacks use various methods but share the common goal of rendering services unavailable to legitimate users.

These attacks are hard to defend against because they can come from many sources, including compromised devices.

How to Identify and Mitigate DoS Attacks

DoS attacks are difficult to mitigate and identify because they often mimic legitimate traffic, blending in with normal data flows. This means detecting a DoS attack requires you to monitor your network traffic for any anomalies closely. Recognising the attack early helps in mitigation.

Effective mitigation strategies involve identifying attack vectors, filtering malicious traffic, and scaling resources to absorb the impact. This can include deploying web application firewalls, intrusion detection systems, and using cloud-based services to distribute the load. These strategies add an additional layer to all your systems as well as do some damage control.

While DoS attacks are challenging due to their variety and complexity, understanding these attacks, and having a robust mitigation strategy is essential. The goal is not only to mitigate ongoing attacks but also to prevent future ones through proactive security measures and infrastructure resilience.

What is a Distributed Denial-of-Service (DDOS) Attack?

When a DoS attack escalates into a Distributed Denial-of-Service (DDoS) attack, it involves multiple systems—potentially thousands—compromised by malicious software to generate attack traffic. These systems form a botnet—a network of infected devices used to flood the target with an overwhelming volume of traffic, rendering it inaccessible.

DDoS attacks are more complex and challenging to mitigate than simple DoS attacks due to their distributed nature. The sheer volume of attack traffic can exceed the target's bandwidth capacity, causing service disruptions.

Protecting Against DOS and DDOS Attacks

Firewalls are the first line of defence against denial-of-service attacks, restricting incoming and outgoing traffic based on predefined rules. Firewalls prevent these by scrutinising each data packet. The firewall then only allows legitimate traffic, significantly reducing the risk of malicious attacks.

Another option is to use a “reverse proxy” service to monitor traffic before it reaches your website. This will absorb attacks and keep blatantly damaging access attempts from reaching your servers.

To protect your business’s network infrastructure from evolving cyber threats, you need to develop a strong security strategy. This includes keeping firewalls up to date and installing advanced security measures specifically designed to guard against DoS and DDoS attacks.

The Impact and Consequences of DoS Attacks on Businesses

Downtime:

1. DoS attacks involve multiple systems flooding the bandwidth or resources of targeted systems.
2. The goal is to render websites or services inoperable, denying service to legitimate users. This leads to downtime and disruption in your business operations.

Financial Consequences:

1. Direct revenue loss due to halted online sales and transactions.
2. Significant expenses for mitigation and recovery efforts.
3. Costs include engaging cybersecurity experts, and investing in security measures, legal fees, and compensation claims.
4. Unpredictability and sophistication of attacks escalate financial burdens.

Impact on Reputation and Customer Trust:

1. Damages your business’s reputation.
2. Consumers expect seamless, uninterrupted online service.
3. Reduces trust and loyalty.
4. Decline in customer base due to loss of confidence.
5. Recovery from reputational damage is lengthy, requiring substantial marketing and customer service investments.