DoS and DDoS Attacks Explored: protection Strategies and Insights

What is a Denial of Service Attack?

Denial-of-Service attacks degrade and disable services by overwhelming a server with more data than it can handle. Hackers target online platforms and networked devices, with the goal of shutting them down to regular business traffic for as long as possible.

How Do DoS Attacks Work?

DoS attacks have two main ways to beat the targeted network: either by exploiting a security flaw that causes the system to shut itself down, or by out-muscling the target network with a higher processing power. For example, the largest volumetric DDoS attack recorded to date was sending 11.5 terabits of data per second. In the latter approach, hackers usually achieve superior bandwidth by using a botnet.

The goal of either method is to overload network resources using erroneous service requests. This renders these resources unavailable to legitimate users. Without a functioning online platform, your businesses could struggle to perform daily operations, be at risk of data loss, and experience costly downtime.

What Are the Most Common Denial of Service Attacks?

DoS email security issues come in various forms, but these are the most prevalent threat types that could cross your server: DDoS, buffer overflow, flood, and email bomb attacks.

Distributed Denial of Service (DDoS) Attacks

Distributed Denial of Service, or DDoS, utilizes the power of multiple infected computers, called a botnet, to overload a system. Rather than using a single device to direct traffic, DDoS botnets can employ hundreds or thousands, if not millions, of compromised devices. Cybercriminals grow their botnets by sending emails with embedded malware that downloads itself throughout computer systems.

Buffer Overflow Attacks

This is a type of security exploit that can crash systems by overwriting critical sections of code. During a buffer overflow DoS attack, cybercriminals target disk and drive space, where the computer's memory and Central Processing Unit (CPU) are located. In a standard attack, buffer overflows cause crashes, sluggish interactions, and the "blue screen of death."

Flood Attacks (ICMP Floods, SYN Floods)

In a flood attack, cybercriminals repeatedly send data packets to a server until they overwhelm the bandwidth, causing a denial of service. There are two main types of flood attacks:

ICMP or “ping” floods disable devices by rapidly sending echo-request packets without waiting for the target to respond. When the victim’s system attempts to reply to the overwhelming packet pile-up, its bandwidth for both incoming and outgoing packets will be used up. At that point, strain on the CPU slows down all of the device’s operations.

SYN floods send false or incomplete server requests that will never be met, thus wasting time and processing power. Impossible connection attempts time out and fail as more requests pour in. While this attack continues, legitimate users will be unable to access the server.

Email Bombs

Email bomb attacks target inboxes with a torrential flood of repetitive emails and auto-subscriptions. Botnets can deliver thousands of emails per minute and make it effectively impossible for the inbox owner to see their normal emails, including security alerts, among the bot-spammed messages. Email bombs can also contain terabytes of information zipped into attachments, and these files overwhelm the email server when they are unpacked for scanning.

Best Practices To Protect Against DoS Attacks

Guarding your system from a DoS attack is complex and requires preemptive planning. The tools below are building blocks that businesses can use to construct a smart anti-DoS security strategy.

DoS Traffic Filtering 

DoS and DDoS attacks exploit the normal functions of the Internet Protocol to cram your bandwidth full of garbage. To defeat them, you need intelligent filtering methods that can let in the traffic you want while keeping out botnets.

For example, Geographic IP filtering blocks all internet traffic from areas where your company is not currently doing business. 

Another approach is Allowlisting, which defines what types of actions are permitted on your network servers and stops any activity that is outside of the allowed parameters. 

Finally, a safe-sender email list can prevent email bombs from blowing up your inbox by restricting sender fraud from spoofed addresses.

DoS Threat Detection and Scrubbing

To stop a DoS attack in progress, the first step is to realize what is happening. By comparing server traffic during an attack to baseline traffic patterns, DoS mitigation services can detect the threat, then move into action.

Scrubbing is a DoS defense that works by diverting suspicious, high-volume traffic into high-capacity servers where they are “scrubbed” or inspected before being allowed to rejoin the flow of legitimate traffic to the server destination that is being targeted.

Filtering, detection, and scrubbing form an interlocking defense in depth that can limit the potential for DoS to hit your business systems.

How DoS and DDoS Attacks Impact Email Security 

In addition to slowing down services, Denial of Service attacks are also used as a “smoke-screen” to cover for simultaneous actions. Hackers might initiate a phishing attack by offering to “help” office workers recover their bombed-out inboxes, or try to install dangerous malware and ransomware while spambots smother your security alerts. That’s why strong email security is critical in preparing for DoS and DDoS attacks. To combat malware threats before they reach your inbox, consider installing a cloud email security service.

Denial of Service FAQ

What is the difference between DoS and DDoS attacks?

DDoS is a type of Denial of Service attack that is defined by being “distributed” or coming from multiple sources. The largest DoS attacks carried out today are DDoS attacks that use botnets to overpower lower-bandwidth targets.

How do I know if my business is under a DDoS attack?

A DDoS attack can be detected by monitoring network traffic levels and comparing activity to a baseline traffic pattern. Unexplained traffic spikes, as well as lowered performance across the network, are signs that an attack could be taking place.

What are the most effective ways to stop a DoS attack?

Multiple layers of smart, IP-based traffic filters combined with DoS detection and scrubbing solutions can prevent DoS attacks from taking down online services.

What role does email security play in preventing DoS attacks?

Email security plays a direct role in stopping email bomb attacks, and is also key to preventing email-borne malware from infecting your devices as part of a botnet.

Can ransomware be delivered during a DoS or DDoS attack?

Yes, DoS and DDoS can be used as a distraction while hackers deliver ransomware. The service downtime that results from DoS can also serve as an additional method of extortion during ransomware schemes.

Shut Down Denial of Service with EnGarde 

Guardian Digital EnGarde Cloud Email Security is a fully managed, comprehensive email security package for businesses. Our multi-layered defensive solution provides you with tools that can be individually tailored for any organization. We are open-source, which means you can see how email security experts are constantly improving our software. Transparent development ensures that EnGarde is ready to go up against the latest tactics in DoS attacks, phishing, and other threats.