What are Denial of Service Attacks?

Cyberattacks have become a fact of life, with data breaches of high-profile businesses and organizations making headline news practically on a daily basis. One common type of cyber threat is a denial of service (DoS) that—as its name implies—renders websites and other online resources unavailable to intended users.

DoS threats come in many flavors, with some directly targeting the underlying server infrastructure. Others exploit vulnerabilities in application and communication protocols.

Unlike other kind of cyberattacks, which are typically launched to establish a long-term foothold and hijack sensitive information, denial of service assaults do not attempt to breach your security perimeter. Rather, they attempt to make your website and servers unavailable to legitimate users. In some cases, however, DoS is also used as a smokescreen for other malicious activities, and to take down security appliances (e.g., web application firewalls).

A successful DoS attack is a highly noticeable event impacting the entire online user base. This makes it a popular weapon of choice for hacktivists, cyber vandals, extortionists and anyone else looking to make a point or champion a cause.

DoS assaults often last for days, weeks and even months at a time, making them extremely destructive to any online organization. They can cause loss of revenues, erode consumer trust, force businesses to spend fortunes in compensations and cause you to suffer long-term reputation damage.

DoS vs. DDoS

The differences between DoS and DDoS are substantive and worth noting. In a DoS attack, a perpetrator uses a single Internet connection to either exploit a software vulnerability or flood a target with fake requests—usually in an attempt to exhaust server resources (e.g., RAM and CPU).

On the other hand, distributed denial of service (DDoS ) attacks are launched from multiple connected devices that are distributed across the Internet. These multi-person, multi-device barrages are generally harder to deflect, mostly due to the sheer volume of devices involved. Unlike single-source DoS attacks, DDoS assaults tend to target the network infrastructure in an attempt to saturate it with huge volumes of traffic.

DDoS attacks also differ in the manner of their execution. DoS attacks are typically launched using homebrewed scripts or DoS tools (e.g., Low Orbit Ion Canon) while DDoS attacks are launched from botnets—large clusters of hacker-controlled connected devices (e.g., cellphones, PCs or routers).