DoS vs. DDoS Attacks: What is the Difference Between Them?

DoS and DDoS are two common types of cyberattacks that can block legitimate users from getting access to your website and interrupt services. Both attacks can cause companies to lose millions of dollars in just a few hours. According to Infosecurity Magazine, the average cost of a successful DDoS attack is $218,000 without accounting for any ransomware costs. Aside from the financial impact, there’s also the disruption of online services, loss of sensitive data, brand reputation damage, and legal and regulatory consequences to consider.

Although these two attacks look similar and both have consequences, the difference between them is more than just the letter “D.”

Denial-of-service attack

A denial-of-service attack (DoS attack) is a type of cyberattack executed from a single system.

During a DoS attack, your web server gets flooded by traffic, making your website or network resource unavailable. Therefore, if your customer service center is receiving constant complaints from customers who can’t get access to your online services while most access requests come from one IP address, you should consider the possibility of a DoS attack.

Types of DoS attacks

• Buffer overflow attacks occur when a program writes more data to a buffer (temporary storage) than it can handle, potentially overwriting adjacent memory and leading to unintended consequences, such as crashing the program or enabling malicious code execution.

• A Ping of Death or ICMP flood attack sends oversized or malformed Internet Control Message Protocol (ICMP) packets to a target, causing the victim's system or network to crash or become unresponsive due to the inability to process these unusually large packets.

• A Teardrop attack involves sending fragmented IP packets with overlapping, incorrect offsets to a target system, exploiting vulnerabilities in its reassembly process and potentially leading to system instability or crashes.

• A flooding attack involves overwhelming a target system or network with a massive volume of traffic, requests, or data, causing resource exhaustion and potentially disrupting or rendering the target's services inaccessible to legitimate users. These attacks aim to flood the target beyond its capacity to handle the incoming traffic, leading to service degradation or downtime.

Distributed denial-of-service attack

A distributed denial-of-service attack (DDoS attack) is usually considered an evolved version of a DoS attack. It has all the negative effects of a DoS attack and is harder to stop. A DDoS attack is executed by having multiple computers on different networks (called a botnet) to send a large amount of requests to your website simultaneously.

If a DoS attack is like starting a one-on-one fight, then a DDoS attack is like besieging your house with people flooding from different directions. What’s worse, these people all look like legitimate visitors because DDoS attackers can compromise legitimate source IPs and leverage them to start an attack. Even if there is no malicious hacker, DDoS can still happen when there is an unexpectedly large spike in traffic to your website. So be vigilant of unusual spikes in traffic, logins, and other important signs of DDoS.

Types of DDoS attacks

• Volumetric attacks inundate a target system or network with an extremely high volume of traffic, often exceeding the systems’ capacity, causing service disruption by consuming available bandwidth and resources.

• Fragmentation attacks involve sending IP packets with incorrect or overlapping fragmentation information, exploiting vulnerabilities in the target's packet reassembly process, and potentially causing system instability or crashes.

• Application layer attacks target specific applications or services within a network, attempting to disrupt or compromise their functionality by exploiting vulnerabilities in the application code, protocols, or server resources.

• A Protocol attack focuses on exploiting weaknesses in network communication protocols, like TCP/IP or UDP packets, to disrupt or manipulate data traffic, potentially leading to network or service issues by causing improper protocol behavior.

Key differences

Although they sound similar, DoS and DDoS attacks couldn’t be more different in the world of cybersecurity, from implementation to sheer scale.

Single source vs. multiple sources

A DoS attack typically uses a single location or internet connection to flood a target system, so they’re naturally easier to detect and sever the connection. However, a DDoS attack has multiple compromised devices or a network of botnets involved. Each one sends a portion of the attacking traffic, making it challenging to trace back to a single source.

Speed of attack

A DDoS attack is typically faster than a DoS attack because it involves multiple sources that simultaneously generate a massive volume of attack traffic. This distributed nature of DDoS attacks allows them to overwhelm the target system more quickly and effectively. In contrast, a DoS attack relies on a single source or a limited number of sources, which may not have the same level of combined bandwidth and resources as a DDoS attack, making it slower and less intense in comparison.

Amount of traffic

A DDoS attack can send a much larger volume of attack traffic compared to a DoS attack, often magnitudes more. DDoS attacks can involve a coordinated effort from numerous sources, which collectively generate a massive amount of traffic, effectively overwhelming the target server. It's not uncommon for DDoS attacks to involve gigabits or terabits of data per second, whereas DoS attacks may involve a fraction of that volume. However, the exact difference in attack traffic can vary widely from one attack to another.

Attack complexity

A DDoS attack is coordinated and includes multiple compromised devices infected with malware, known as bots, to form a botnet under the control of a central command-and-control (C&C) server. On the other hand, a DoS attack usually leverages a script or specialized tool to execute the attack, originating from a single machine or source.

DoS and DDoS mitigation with SiteLock

While DoS attacks are often easier to detect and prevent than DDoS attacks, both are significant threats to websites and businesses.. To help you mitigate these malicious attacks, SiteLock offers comprehensive DDoS protection solutions, which include:

• Website monitoring to identify and detect abnormal traffic patterns or malware.

• Automatic malware removal to prevent site downtime.

• A website application layer firewall (WAF) to block attacks and prevent malicious traffic from overwhelming your website.

• A content delivery system (CDN) to distribute traffic and absorb DDoS attacks, reducing the impact on your primary servers.

• Regular patching and updates to keep your software current with the latest security patches to reduce vulnerabilities automatically.

ExploreSiteLock website security plans and find the security solution that fits your site.